Darren Naish: Tetrapod Zoology

Tetrapod Zoology ver 2

2007-01-24T17:58:00.000Z

It is done: Tetrapod Zoology is moving. Please go over to....

http://scienceblogs.com/tetrapodzoology/

See you on the other side!

Goodbye blogspot....

2007-01-23T00:36:00.000Z

Remember I said that things were going to change? (go here, for example). Well, things are going to change. Please watch this space: it will take a few days to happen, but I will keep you posted.

Why the chalicothere, I hear you ask? Well that would be telling, wouldn't it. Sorry about lack of promised vampire post, it's still due to appear. Sorry also to those owed emails, please be patient.

UPDATE (added 23-1-2007): I should be able to let you know what's happening later today. And no prizes for the many that have guessed correctly already.

UPDATE 2 (added in the small hours of the morning on 24-1-2007): ok, things are nearly ready. Drumroll. So, I said that things are changing. No, I do not (yet) have a proper job. No, I am not moving to myspace (very funny). Am I moving to scienceblogs? Yes. As many of you correctly guessed, Tetrapod Zoology is moving, so you will need to update your browsers, change links etc. The full transition is occurring as I type, and I should have the url by the end of today: though the first post is up and ready (and I can view it), I don't know if it's publicly accessible, so don't waste your time by trying to find it. So far as I know, the year's archive of posts here on blogspot will remain, and of course I'll be linking back to these posts from time to time. Please check back soon for the new url...

Happy first birthday Tetrapod Zoology (part II)

2007-01-21T01:15:00.000Z

As discussed in the previous post, today (January 21 2007) is Tetrapod Zoology’s first birthday. Hooray: more champagne, please. You’ll need to read part I to make sense of the following. Anyway, here we go.

Tetrapod Zoology: horribly biased

As mentioned in the previous post, given that I do not blog ‘to a plan’, I want to know what the spread of subjects I’ve blogged about might tell me. Might they reflect my ‘real’ interests, or might they perhaps indicate which areas within tetrapod zoology are currently the most happening, interesting or sexy? I don’t know, but I find the results pretty surprising. In terms of broad coverage of subject areas, we see from the adjacent graph [click for larger version, of course] that I’ve written more about reptiles (including birds) than I have about other tetrapod groups. It’s also notable that the number of miscellaneous posts – those that cover various assorted crap and aren’t really focused on any one group of animals – is reasonably high.

The prevalence of reptiles is not so surprising, given that I specialize on dinosaurs and other Mesozoic reptiles, but what does surprise me is how the reptiles break down when we look at them by group. Turtles, crurotarsans (the clade that includes crocodilians and their extinct relatives) and pterosaurs are equally represented, but with only a few posts each. Despite (or, perhaps, because of) the fact that I have just been working on them for seven years, non-avian theropods haven’t featured heavily. I must rectify this. Squamates (lizards, snakes and kin) do a bit better, and would have featured even more on the blog if I’d gotten round to finishing the articles I’ve started on sea snakes, island-endemic lizards and anguids. The two most surprising groups are sauropods (represented by 10 posts), and birds (represented by 24 posts). Yikes, does this mean that I’m more ‘interested’ in sauropods and birds – and even squamates – than in non-avian theropods? It’s something for me to think about. The prevalence of birds is just downright scary: more on it in a moment.

A similarly surprising thing happens when we break down all the mammal posts. Of the groups covered (and keep in mind that a vast number of areas haven’t been covered at all), hoofed mammals are out in front, and rodents and primates are reasonably well represented. This surprises me because I’d always imagined that these were the least interesting mammals: way outclassed by marsupials, monotremes, pangolins, bats and xenarthrans. Yet I’ve hardly blogged at all on any of these topics. Yikes, do I really find deer and voles more interesting than sloths, thylacines and echidnas? Again, it’s something I’ll have to think about, and perhaps aim to rectify in future.

Looking at subject areas broken down more specifically (this time across all material covered), the overall picture is, again, somewhat surprising. Lissamphibians feature poorly and Palaeozoic and Mesozoic amphibian groups like lepospondyls and temnospondyls don’t feature at all. This is bad as I actually spent a lot of time doing research on these groups in 2006. Rodents, primates and turtles are reasonably represented overall (which, again, surprises me as I just never imagined that I’d end up writing much about these groups). The red bars show those subject areas that were particularly well represented: miscellaneous stuff, hoofed mammals, sauropods and birds! There is no way this is what I would have predicted. The big score that birds get is worrying. Granted, I haven’t broken Aves down into constituent clades, so the results aren’t exactly balanced, but – again – I’m asking myself: does this really reflect my personal interests? Am I really more interested in birds than in other tetrapods? Or is it just that birds were particularly newsworthy in 2006? I think that the latter point is significant here, as the posts on eagle owls, phorusrhacids, the Madagascar pochard, and the 10 bird meme were not spin-offs of my own ideas, but were instead initiated by the writings of others.

For those who say nice things about my blog, the good news is that this is still just the beginning, and there is a vast amount of material I have yet to complete and post, or even write. Ironically, I still haven’t managed to complete many articles that I have started writing way back at the start of 2006, including those on temnospondyls, rhinogradentians, Haast’s eagle, Piltdown and amphisbaenians. To those looking forward to the posts on these subjects, all I can say it: please bear with me, they will be completed and posted eventually! As I’ve said before, if I could devote more time to blog writing I would. At the moment life gets in the way.

So, happy first birthday Tetrapod Zoology. I hope you’ve enjoyed the ride so far. Many thanks to all those who have helped and supported me over the past year, to those who assist in obtaining literature, to those who advise and point out errors, to those who post comments, and to all who read and/or visit the blog [UPDATE: to see what happened next go here].

Happy first birthday Tetrapod Zoology (part I)

2007-01-21T00:30:00.000Z

On Saturday 21^st January 2006 – that is, one year ago – I decided, entirely on a whim, to start my own blog. I’d been reading various people’s blogs for a while and it was on that night that the thought of writing one of my own occurred to me. Of course, it was just about the worse time to do this, given that I was scheduled to complete my PhD in April of that year, and I was already too busy with too many additional commitments. But I did it anyway, and while lying in bed later that night I felt the over-riding urge to get up, switch the computer on and write the first of my patented over-long, tediously detailed blog essays. It was on giant killer eagles, a favourite subject of mine, and one that I was to return to several times later on in the year. It marked the beginning of a new and highly rewarding phase in my life.

So, today is Tetrapod Zoology’s first birthday. In this post (and part II) I want to look back at a year’s blogging: given that I do not really blog ‘to a plan’ (I simply write about those subjects that I bump into, or find particularly interesting on the spur of the moment), I’m interested in seeing what I might learn about my blogging habits. It’s also worth reviewing Tetrapod Zoology’s changing fortunes, and on looking back at my own circumstances, during the year that’s past. You’ll be pleased to hear that we (as in, Toni, Will and myself) celebrated Tetrapod Zoology’s first birthday by visiting the Natural History Museum in London. Above is a photo of the robotic tyrannosaur to prove it. And sorry if you were expecting the vampire post… it will follow shortly.

A year in the life

It feels like a lot happened in 2006, though I’m not sure if it really did. I spent time in the field looking at obscure British reptiles and amphibians, wild deer, rodents, bats and birds, and I taught Will stuff about tracking and field sign. I visited the farm many times (see adjacent image), and the zoo where I was impressed by takins, peccaries, sleeping anteaters and rhinos. Feedback on the blog increased and, thanks to it, I made lots of new friends. The main event of 2006 was, of course, the completion of my PhD on Wealden theropods. By repeatedly staying up until 05-00 each morning, I managed to get the thing completed, and at the start of June I had the viva and completed the process in full. Besides being kept busy with my editorial work for Cretaceous Research, in late 2006 I began an adult-education course on the evolution and diversity of tetrapods for the WEA (Workers Educational Authority), and at the start of 2007 I am currently teaching the second such course.

Since completing the PhD I’ve been unable to get a job in academia, despite strenuous efforts, and life has been very hard. However, working on the assumption that I will somehow get back into the system, I have continued to do research when time allows. Several academic projects that have been mentioned on the blog have yet to come to fruition, including that long-delayed manuscript on British dinosaur diversity, and work on Cretaceous Spanish vertebrates, Wealden sauropods, and azhdarchid ecology. In July, Dave Martill and I finally published our paper on Tupuxuara and the affinities of azhdarchoid pterosaurs (to a flurry of media attention), and Dave, Sarah Fielding and I published a review of Kimmeridge Clay dinosaurs later in the year. I am routinely asked to do talks for local natural history and geology groups, and in 2006 I lectured on ichthyosaurs, British big cats and Wealden dinosaurs. I also did TV interviews on theropods and marine reptiles, a podcast for George Kenney’s Electric Politics site, and late in the year I was commissioned to assist in the development of a TV programme featuring computer-generated dinosaurs.

While all of this was going on, I have researched and published blog articles on… well, a lot of stuff (see part II). For me, blogging is great for two main reasons. Firstly, it’s very easy compared to conventional publishing. An article of a 1000 words can be written, illustrated, formatted and published within an hour or so. Secondly, the accessibility and popularity of blogs means that blog posts are almost certainly read by more people than are anything within conventionally published media.

Troughs, peaks and mega-peaks

Naturally, if you maintain a web site of any sort, you’re interested in how much, or how little, traffic you’re getting. Blogspot doesn’t provide a web counter for every blog of course, so the only way to check your traffic is to see how many people have viewed your profile. However, of every 2000 people that visit a blog, perhaps 1 looks at the profile, so this isn’t a reliable guide. So in September I installed a web counter (provided, free by bravenet), and by November 2006 it had counted 50,000 hits, which ain’t bad. At the time of writing, the current number of average daily hits is round about 500 (see adjacent graph, depicting traffic on 12th January 2007), though this was more like 300 prior to November 2006 or so.

Within a short length of time I learnt that certain types of posts got more hits than others, and this partly explains why – in November 2006 – I blogged about sasquatch. Thanks to the web counter, I was able to watch my traffic soar to a high of about 3000 a day. It seems that mentions of the blog on scienceblogs.com sites and anomalist.com result in a surge of traffic: the graph shown here shows what happened on the 18th January 2007 when PZ Myers linked to my post on Darwin’s beard. A far more remarkable peak – a mega-peak – occurred however during the Christmas holiday, when (over the space of three days) the total number of hits jumped from 50,000 to over 80,000. I initially thought this was some kind of software glitch, but it wasn’t (unfortunately, I never thought to save the bravenet counter graph generated at the time). It seems that Pekka Komi’s remarkable 2006 photos of the Golden eagle scrapping with the fox had proved incredibly popular, and after a link to my blog was listed on digg.com, things went nuts. So I learnt that neat photos make all the difference, if, that is, traffic is what you’re interested in.

Continued in part II….

The evolution of vampires

2007-01-18T00:17:00.000Z

Coming soon: musings on a possible path to passerine parasitism. Also extinct plasma-quaffing microbats, and maybe pterosaurs (again).

Update: go here, here or here...

Why I hate Darwin’s beard

2007-01-13T00:02:00.000Z

Here’s a little known fact. Charles Robert Darwin (1809-1882), the most important biologist of all time, did not spend his entire life as an old man. I despise stereotypes, especially those that are totally erroneous, and whenever I see a picture of ‘old man Darwin’ I wonder: why is it that so many of our most important scientists are consistently portrayed as old men? Don’t get me wrong, I have nothing in particular against old men, it’s just that this tradition is annoying and misleading, and perpetuated by a society that seems to want scientists to be oddballs that operate on the fringes of society.

Darwin is the ultimate example of this sort of thing: ask people what Darwin looked like and I reckon 99% or more will describe an aged, bald-headed individual with a bushy beard, photographed in black and white and wearing a suit. Of course this is the way in which Darwin is virtually always depicted, in part because photography only became widespread in the 1850s (and by the 1860s Darwin was indeed balding and bearded). But the obvious point worth making – and drumming home whenever it’s appropriate – is that Darwin didn’t spend his entire life as an old man of 70 years of age. While it’s correct that he was still actively involved in research at this age (in 1879 he finished a work on climbing plants, and in 1881 he published work on the ecological importance of earthworms), it’s neither fair nor appropriate to imagine him doing all of his important work at this stage in his life.

Quite the opposite: in fact most of the stuff that Darwin is best known for happened when he was disgustingly young (I’m in my thi - - fourth decade* and already feel angry and bitter about the absurd brevity of life). Darwin was on The Beagle between late December 1831 and October 1836. In 1832 he visited Patagonia and collected the remains of glyptodonts, megatheres and toxodonts. In 1833 he arrived at the Falkland Islands, where he met and ‘collected’ specimens of the now extinct Falkland Island fox or Warrah Dusicyon australis (image at left by John Keulemans), and in September 1835 The Beagle reached the Galapagos Islands. All of this happened when Darwin was between the ages of 22 and 27, with his narrative of the expedition being published in 1839, when he was just 30 (Desmond & James 1991). He was a young man when all of this happened.

* Many, many thanks to the good friends who reminded me how old I really am. I was young once.

We know that Darwin had been seriously entertaining ideas about transmutation, or evolution, since the mid 1830s. But he felt forced to publish his best known work, On the Origin of Species By Natural Selection (Darwin 1859), earlier than he would have liked because he learnt in 1858 that Alfred Russell Wallace (1823-1913) had essentially come up with the same ideas regarding natural selection. Origin was therefore published in 1859 (in fact it was published in November 1859, while Darwin was deliberately avoiding things by being on holiday at Ilkley Spa in Yorkshire), and at this time Darwin was 51. Still he had no beard: the image at left shows him at this age.

In fact Darwin didn’t grow that beard until early 1866 when he was 56, and he may have done so in a deliberate effort to disguise himself. This must have been successful: Darwin became close friends with Joseph Hooker (1817-1911) after they met in 1839 (later, in 1846, Hooker became Darwin’s right-hand-man as regards botanical issues), yet Hooker failed to recognise the now-bearded Darwin at a Royal Society meeting of April 1866.

So, it’s no big deal, but I sooo wish that Darwin, and all those other great scientists, weren’t stereotyped so much. Images of the young, pre-bearded Darwin do exist, and given that he was between the ages of 22 and 51 when all of the things he is famous for happened, I have to wonder why we don’t see such images more often. We would all do our field some good if we stopped perpetuating stereotypes that have negative connotations. Think of this next time you think of Darwin.

Moving on: I have been kept busy the last few days with Mesozoic frogs, pterosaurs (again), gazumping and aetosaurs… and I must stop knuckle-walking. It hurts. I’m serious: future post to come on quadrupedality in humans.

For the latest news on Tetrapod Zoology do go here.

Refs - -

Darwin, C. 1859. On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. John Murray, London.

Desmond, A. & James, M. 1991. Darwin. Penguin, London.

Biggest sauropod ever (part…. II)

2007-01-10T22:45:00.000Z

In the previous post we looked at the obscure and poorly known mega-sauropod Amphicoelias fragillimus, described in 1878 on the basis of an incomplete but enormous dorsal vertebra and the distal end of a femur. Its details show that it was a diplodocoid, and thus related to more familiar taxa like Diplodocus and Apatosaurus. Despite its absurd size – suggesting (by comparison with other diplodocoids) a total length of 60 m – this material somehow vanished prior to 1921. Due in part to these facts (and also, perhaps, to its poorly publicised and unfamiliar-sounding – or ‘crappy’ – name), Amphicoelias fragillimus was to be all but forgotten in the decades that followed…

During the 1990s, little-known articles by John McIntosh (revered older statesman of sauropod research) and Greg Paul looked briefly at A. fragillimus. McIntosh (1998) went through Cope’s inventories of the Garden Park discoveries (these records had been missed by Henry Osborn and Charles Mook in their 1921 review of Cope’s sauropod collection) and found that, perhaps because the contents of several crates have no surviving records, the shipment of A. fragillimus to New York wasn’t recorded. Paul (1994a, b) estimated the size of A. fragillimus based on the dimensions provided by Cope, suggesting (again, based on comparison with more completely known diplodocoids) a total length of 40-60 m, a weight of 100-150 tons, and that it would have been 9 m tall at the hips, and with thighs 3.8 m long.

The news is that, at long last, a proper reappraisal of this mysterious giant has finally appeared: it’s a new paper by Ken Carpenter of the Denver Museum of Nature and Science, and while, sadly, it doesn’t report the discovery of a new, articulated A. fragillimus specimen, it does cover pretty much everything we know about this dinosaur (Carpenter 2006). By the way, Carpenter and colleagues have tried looking for additional remains of A. fragillimus, thus far without success. Actually, I have to note here the rumour that new A. fragillimus material has been discovered, and that it will be discussed at the 2008 Society of Vertebrate Paleontology meeting. We shall see [adjacent image is Cope’s original 1878 figure of the A. fragillimus vertebra. I ripped it off from Matt Celeskey’s post about A. fragillimus from August of last year (go here). Sorry Matt].

Was A. fragillimus a hoax?

Unsurprisingly, quite a few people have been sceptical about the existence of this all-too-conveniently lost mega-sauropod. Can we be sure that it ever really existed, or could it be that Cope was pulling a fast one in order to beat his rival, Othniel Charles Marsh, hands-down in an effort to describe the biggest sauropod? As attractive as this scenario might appear, hoaxing is highly, highly unlikely. Consider the following:-

-- Cope was very specific about all the discovery details of A. fragillimus. According to his field notes, it was collected in late 1877 by Oramel Lucas (described by Cope as his ‘indefatigable friend’) at Garden Park, specifically from quarry III, a site southwest of the hill known today as Cope’s Nipple (Carpenter 2006). The rocks here yielded several other particularly large Morrison Formation dinosaurs (such as Camarasaurus supremus).

-- Furthermore, the shipment records discovered by McIntosh show that Oramel Lucas and his brother Ira knew of A. fragillimus and labelled some remains with this name (McIntosh 1998, p. 487 and p. 498). If it was a hoax, then the Lucas brothers must have been in on it too, which now makes it a conspiracy.

-- The conspiracy would have to extend even further, as an American Museum of Natural History catalogue number, AMNH 5777, was reserved for the A. fragillimus material.

-- The rivalry that existed between Cope and Marsh is also relevant here (Marsh is pictured at left). As is well known, Marsh enjoyed making a very public fool of Cope when he made a technical error (Storrs 1994, Davidson 2002), and when he disagreed with Cope, or thought him wrong, Marsh was tediously pedantic in his criticisms (see Marsh’s 1873 papers on dinoceratans, for example). Marsh never criticised, nor even questioned, the reality of A. fragillimus. Carpenter (2006) notes that ‘Marsh is known to have employed spies to keep tabs on what Cope was collecting, and it is quite possible that he had independent confirmation for the immense size of A. fragillimus’ (p. 134).

-- Cope’s drawing of A. fragillimus is accurate-looking and elaborate, and his description refers to small detailed features, all of which conform in details with what we know of diplodocoid vertebrae (part of the description is reproduced at left: from here). He would have to have made all of this stuff up if the specimen was a hoax: it’s not as if the only record of A. fragillimus is a scribbled fragment in a diary, saying ‘On Tuesday I saw the biggest vertebra ever… it was thiiiiis big…’. Rather, the material is documented, in detail, in a proper technical paper. To hoax an entire paper of this sort would be severe science-crime, and there is no indication that Cope was unscrupulous or dastardly, or prepared to stoop this low.

-- It is noteworthy that workers well known for their methodical and conservative approach to sauropod studies (notably John McIntosh) have accepted Cope at his word. Osborn, who succeeded Cope as vertebrate palaeontologist for the US Geological Survey and is well known for speaking his mind when he had a problem with something, also never voiced doubts about A. fragillimus.

All of this is circumstantial, for sure, but I agree with Carpenter (and others) that the idea of Cope perpetrating a hoax of this magnitude is pretty much unthinkable. I think we have to assume that the specimens really existed. Therefore, they must have become lost or destroyed some time between 1878 and 1921 (when Osborn and Mook failed to find them). As Carpenter (2006) points out, it in fact appears likely that the material was too fragile to survive, and that it crumbled to bits some time after its discovery. Matt Celeskey also noted this possibility (go here). Cope commented on this fragility, writing ‘in the extreme tenuity of all its parts, this vertebra exceeds this type of those already described, so that much care was requisite to secure its preservation’ (p. 563), and his drawing also suggests that the vertebra had been subjected to extensive weathering and hence was already fragile. Indeed its fragile nature explains the specific name he chose for it.

Furthermore, ‘preservatives had not yet been employed to harden fossil bones, the first of which was a sodium silicate solution used in O. C. Marsh’s preparation lab at Yale University beginning in the early 1880s’ (Carpenter 2006, p. 134). Support for the hypothesis that the material simply did not survive collection and storage comes from the fact that, within recent years, a Camarasaurus supremus vertebra collected from the same area is known to have crumbled into small useless fragments.

The other Amphicoelias

As I’ve now mentioned a few times, the detailed anatomy of the A. fragillimus vertebra (as figured by Cope) shows us that this sauropod was a diplodocoid. We can make a confident statement like this because it is relatively easy to distinguish the different sauropod clades on the basis of their vertebral anatomy, and A. fragillimus has all the distinctive anatomical features typical of diplodocoids. In fact it strongly resembles the vertebrae of the first named species of Amphicoelias, A. altus, which Cope described in February 1878.

A. altus is poorly known, but not as poorly known as A. fragillimus: it was first described for vertebrae, a pubic bone and a femur (Cope 1878), but a scapula, coracoid, ulna and partial skull were later referred to it. Based on these remains, A. altus was similar in size to Diplodocus carnegii and probably around 25 m long (Paul 1994a, b), and it is particularly interesting among diplodocoids in that its femora were markedly elongate and slender. Some workers have regarded A. altus as particularly close to Diplodocus, in which case it would be a diplodocid diplodocoid, and probably a diplodocine diplodocid diplodocoid. However, it has also been asserted that A. altus was a basal diplodocoid, and thus more archaic than diplodocids and other flagellicaudatan diplodocoids (that’s right, I said flagellicaudatan) [adjacent image shows Diplodocus mount at Denver Museum of Nature and Science].

Was Cope right in referring his second Amphicoelias species to the same genus as the first? Several authors have thought so, and in fact have gone so far as to state that ‘it is doubtful … if the characters described by Cope warrant the placing of the type [of A. fragillimus] in another species different from A. altus’ (Osborn & Mook 1921, p. 279), or ‘there is no reason not to consider [A. fragillimus] a very large individual of A. altus’ (McIntosh 1998, p. 502). If this is true then, like A. altus, it’s reasonable to assume that A. fragillimus was also superficially Diplodocus-like, and with particularly elongate, slender femora (a shocking idea given the animal’s size).

Carpenter argues in his new paper that, in fact, A. fragillimus seems to have differed from A. altus in a number of anatomical details, and that the two might not have been congeneric after all. As he notes, this remains untestable in the absence of better remains however. Let’s all hope and pray that a new generic name is up for grabs, and I don’t want any ‘superlative + saurus’ nominations.

One final thing. What’s with the image at the top of the page? I discovered it while googling Amphicoelias. Huh, in my day the only decent zoid was Hellrunner... For the story on the image at left go here (no, that’s not an Amphicoelias vertebra, it’s Matt Wedel. The bone, however, is from a diplodocoid... although not an Amphicoelias), and for previous posts on sauropods see the series on ‘Angloposeidon’, the Christmas post on Turiasaurus, some assorted ramblings on British Wealden sauropods, and a post devoted entirely to the anatomy of their hands.

Refs - -

Carpenter, K. 2006. Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus Cope, 1878. New Mexico Museum of Natural History and Science, Bulletin 36, 131-137.

Cope, E. D. 1878. On the saurians recently discovered in the Dakota Beds of Colorado. The American Naturalist 12 (2), 71-85.

Davidson, J. P. 2002. Bonehead mistakes: the backround in scientific literature and illustrations for Edward Drinker Cope’s first restoration of Elasmosaurus platyurus. Proceedings of the Academy of Natural Sciences of Philadelphia 152, 215-240.

McIntosh, J. S. 1998. New information about the Cope collection of sauropods from Garden Park, Colorado. Modern Geology 23, 481-506.

Osborn, H. F. & Mook, C. C. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3, 247-287.

Paul, G. S. 1994a. Big sauropods – really, really big sauropods. The Dinosaur Report Fall 1994, 12-13.

- . 1994b. Is Garden Park home to the world’s largest known land animal? Tracks in Time 4 (5), 1.

Storrs, G. W. 1984. Elasmosaurus platyurus and a page from the Cope-Marsh war. Discovery 17 (2), 25-27.

Biggest…. sauropod…. ever (part…. I)

2007-01-09T23:11:00.000Z

Finally, it’s that post on gigantic mega-sauropods you’ve all been oh-so-patiently waiting for. Note that I’ve decided to do a new thing, and have left the ‘teaser post’ on its own (rather than over-writing it with this new version). Talking of new things, recall that something about my blogging habits is set to change soon.. the word is already on the street (to use the words of Carel Brest van Kempen), but I’m going to keep quiet about it for a bit longer. All will be revealed [UPDATE: go here for the news]. Anyway, to business. Even if you’re not an expert on dinosaurs, it’s likely that you’ve heard – firstly – that some sauropods were rily, rily big and – secondly – that these biggest of the big included such whoppers as Seismosaurus, Supersaurus and Argentinosaurus. It’s always helpful that their names are easy to remember. Recent work has not only resulted in the publication of reasonably accurate size estimates for these dinosaurs, it has also clarified their taxonomy and phylogenetic positions.

Supersaurus vivianae from the Morrison Formation of Colorado is, despite its name, a valid taxon – specifically it’s a diplodocid diplodocoid, and apparently an apatosaurine (the image at the top of page shows a new skeletal mount of this taxon). Recent estimates put its total length at 33 m. The most oft-figured bit of Supersaurus is its immense scapulocoracoid: it’s usually depicted with the late Jim Jensen, its discoverer and describer, lying alongside it. For a change, here (at left) is a curious new take on the theme (borrowed from here). Oh, and if you’re wondering about Ultrasauros (originally informally named Ultrasaurus: note the spelling difference), it’s no longer regarded as a valid taxon: the type material - a dorsal vertebra - was shown by Brian Curtice and colleagues (Curtice et al. 1996) to belong to Supersaurus (come back Brian, all is forgiven!) while the famous Ultrasauros scapulocoracoid seems to belong to Brachiosaurus. Below, at left, you can see dead fish expert Graeme Elliott standing alongside the Ultrasauros scapulocoracoid (go here for hilarious caption, sorry Graeme).

Moving on, Seismosaurus hallorum (originally described as S. halli), from the Morrison Formation of New Mexico, is also a diplodocid diplodocoid, but recent work indicates that it is not generically distinct from Diplodocus and should thus be renamed Diplodocus hallorum. Originally claimed to be over 40 m long, new estimates put it between 30 and 35 m. Supersaurus and Diplodocus hallorum, being relatively gracile diplodocids, probably weighed between 25 and 50 tons (Paul 1994a, b, 1997).

A few more super-sauropods have been added to the list in recent years. Most are titanosaurs, the predominantly Cretaceous sauropod clade originally thought to be late-surviving relatives of diplodocoids but now known to be close kin of the short-skulled camarasaurs and brachiosaurs. Argentinosaurus huinculensis, named in 1993, is a huge titanosaur from the Upper Cretaceous Río Limay Formation of Argentina: it was perhaps 30 m long. Paralititan stromeri is another massive titanosaur, this time from the Upper Cretaceous of Egypt. Estimated by its describers as having been around 30 m long, it has more recently been down-sized to a mere 26 m (image below left is Todd Marshall’s painting of Paralititan, taken from here. Go here for yours truly posing in bizarre fashion with the same image). Puertasaurus reuili, named in 2005 and from the Upper Cretaceous Pari Aike Formation of Argentina, was similar in size to these forms. Finally, Turiasaurus riodevensis is a gigantic Spanish form, and it’s not a titanosaur, belonging instead to a hitherto unrecognised clade termed Turiasauria. It was described at the end of 2006 (go here for more) and is one of the biggest sauropods known, with a length of 36-39 m.

Exactly how heavy these mega-sauropods were is mildly controversial. Accurate mass estimates generally agree that they were on the order of 80-90 tons, but Royo-Torres et al. (2006), the describers of Turiasaurus, put this animal at half this. However, they used a notoriously unreliable method of estimating weight.

While you might have heard of Supersaurus, Seimosaurus or Argentinosaurus – and perhaps even Turiasaurus and Paralititan – have you heard of… Amphicoelias fragillimus? Well, ok, if you’re a dinosaur ubernerd then the answer will be yes, but not if you’re a normal person. Though described as long ago as 1878, this sauropod has remained decidedly obscure and hardly heard of until pretty recently. I’ve done my part for the cause, having mentioned it at every opportunity: in both Dinosaurs of the Isle of Wight, and Walking With Dinosaurs: The Evidence, it’s discussed and touted as, possibly, the biggest sauropod of them all. Naish & Martill (2001), for example, stated ‘What has recently been claimed as the biggest of all sauropods and, indeed, the biggest of all land animals, is actually a specimen discovered in 1878. Based only on a single enormous vertebra, now lost, Amphicoelias fragillimus has been estimated to have reached a length of 60 m and may have attained a weight of 150 tons!’ (p. 230). If these estimates are valid, then this animal was twice as long as Supersaurus and Diplodocus, and perhaps over four times heavier. Err, gosh.

Amphicoelias fragillimus, giant of giants

In August 1878 the famous and prolific scientist* Edward Drinker Cope (1840-1897), portrait at left, described a new immense sauropod, Amphicoelias fragillimus, from the Garden Park quarries of the Morrison Formation of Colorado. It was represented only by an incomplete dorsal vertebra and the distal end of a femur (contra Naish & Martill above: whoops!). A good drawing of the vertebra was provided (Cope 1878), showing that this sauropod was clearly a diplodocoid: a member of the same sauropod clade as Diplodocus, Apatosaurus and their relatives (the name Diplodocimorpha is also sometimes used for these animals: see Taylor & Naish 2005: free pdf available here). The big deal is how, err, big these remains were. The partial vertebra had a preserved height of 1.5 m and, when reconstructed on the basis of comparison with complete diplodocoid vertebrae, has a total height of 2.7 m. Again… gosh (or words to that effect).

* Though usually described (by palaeontologists) as a palaeontologist, Cope was also an accomplished herpetologist and ichthyologist, which explains the name of the journal Copeia.

If history were fair, we would all have grown up familiar with Cope’s hyper-enormous Amphicoelias fragillimus, and we would be less impressed by Brachiosaurus and Balaenoptera, let alone with paltry little 20-m long sauropods like ‘Angloposeidon’ (go here). But it was not to be, and it was to sink into the morass of obscurity. In a major 1921 review of Cope’s sauropods, Henry Fairfield Osborn and Charles Mook noted that they were unable to locate the immense vertebra in Cope’s sauropod collection (Osborn & Mook 1921), today at the American Museum of Natural History (New York). It was lost.

And… I’ll have to stop there. The rest of the story will come in part II: I am aiming to post it tomorrow (10th Jan 2007). It concentrates on those recent studies that have looked at this species, and one of the most-asked questions about this remarkable dinosaur: was it a hoax? Stay tuned, all will be revealed. And I’m not stringing it out on purpose – I honestly don’t have enough time in my life to deal with all this stuff in one go. Sigh. And apologies to Ken Carpenter, who is no doubt wondering why I haven’t yet cited his paper…

Refs - -

Cope, E. D. 1878. A new species of Amphicoelias. American Naturalist 12, 563-565.

Curtice, B. D., Stadtman, K. L. & Curtice, L. J. 1996. A reassessment of Ultrasauros macintoshi (Jensen, 1985). In Morales, M. (ed) The Continental Jurassic. Museum of Northern Arizona Bulletin 60, 87-95.

Davidson, J. P. 2002. Bonehead mistakes: the backround in scientific literature and illustrations for Edward Drinker Cope's first restoration of Elasmosaurus platyurus. Proceedings of the Academy of Natural Sciences of Philadelphia 152, 215-240.

McIntosh, J. S. 1998. New information about the Cope collection of sauropods from Garden Park, Colorado. Modern Geology 23, 481-506.

Naish, D. & Martill, D. M. 2001. Saurischian dinosaurs 1: Sauropods. In Martill, D. M. & Naish, D. (eds) Dinosaurs of the Isle of Wight. The Palaeontological Association (London), pp. 185-241.

Osborn, H. F. & Mook, C. C. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3, 247-287.

Paul, G. S. 1994a. Is Garden Park home to the world’s largest known land animal? Tracks in Time 4 (5), 1.

- . 1994b. Big sauropods – really, really big sauropods. The Dinosaur Report Fall 1994, 12-13.

- . 1997. Dinosaur models: the good, the bad, and using them to estimate the mass of dinosaurs. In Wolberg, D. L., Stump, E. & Rosenberg, G. D. (eds) Dinofest International: Proceedings of a Symposium Sponsored by Arizona State University. Academy of Natural Sciences (Philadelphia), pp. 129-154.

Royo-Torres, R., Cobos, A. & Alcalá, L. 2006. A giant European dinosaur and a new sauropod clade. Science 314, 1925-1927.

Taylor, M. P. & Naish, D. 2005. The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda). PaleoBios 25, 1-7.

Finally, some hot giant amphicoelian action

2007-01-05T21:37:00.000Z

[click for larger version. Diagram produced by Ken Carpenter]

FULL POST TO COME LATER TODAY (9th Jan 2007)

After years of suffering all-too-brief mentions, asides and speculative remarks, the oft-alluded-to but long-neglected gigantic diplodocoid sauropod Amphicoelias fragillimus has been re-examined. Named by Edward Drinker Cope in 1878, it is known only from scant material (a single partial vertebra and fragment of femur) that – to make a bad situation worse – was somehow lost prior to the 1920s. But scant and lost or not, this material shows that A. fragillimus was immense, and in fact the most immense of all mega-sauropods. Full post to follow soon…

Thanks to Mike P. Taylor for the heads-up.

And for the latest news on Tetrapod Zoology do go here.

That’s no mystery carnivore (part II)… it’s a giant squirrel!

2007-01-04T20:07:00.000Z

In the previous post we looked anew at the controversial Kayan Mentarang animal: that reddish long-tailed Bornean mammal, photographed in 2003 by a World Wildlife Fund team, and announced to the world in December 2005. Widely hailed by many as a probable civet, it was argued by Chapron et al. (2006) to most likely represent Hose’s civet Diplogale hosei, a poorly known, apparently rare civet named in 1892. But despite the apparent strengths of this identification (and the fact that it came from an authoritative source: one of the authors in particular [Géraldine Veron] is a noted expert on viverrids), it was really a non-starter for several obvious reasons.

The Kayan Mentarang animal is reddish-brown while Hose’s civet is dark brown or blackish. Chapron et al. (2006) got round this by arguing either that the animal’s colour had been ‘affected by the flash of the camera’, or that the individual was an unusual colour variant. Both suggestions fail to explain the absence of the pale facial, neck and flank markings present in Hose’s civet. Shuker (2006) noted that – contrary to Chapron et al.’s claims of morphological similarity – the long hindlimbs of the Kayan Mentarang animal made it look more suited for arboreal life than is the predominantly terrestrial Hose’s civet. Furthermore, the Kayan Mentarang animal has really tiny ears while Hose’s civet has far larger ones, and the Kayan Mentarang animal also has (proportionally) a much longer tail than Hose’s civet. So the idea that the Kayan Mentarang animal is actually a specimen of Hose’s civet is poorly founded and not likely.

Hose’s civet not so poorly known

Worth noting here is that – while undeniably rarely recorded and poorly known – Hose’s civet isn’t as rarely recorded and poorly known as some authors have recently been saying. Observations were published in 2002 (Francis 2002) and 2003 (Dinets 2003), and camera-trap photos were taken between December 2003 and March 2004 (Wells et al. 2005): the adjacent image shows one of the latter photos, taken in lowland rainforest in Sabah, Borneo. The fact that Hose’s civet has now been recorded in lowland forest as well as in montane regions at least suggests that it’s ‘more common and widespread than previously thought’ (Wells et al. 2005, p. 13).

The case for the squirrel

Anyway, if the Kayan Mentarang animal isn’t Hose’s civet, what is it? As mentioned above, a new identification has now been published, and hasn’t been as well reported as was the viverrid identification, which is surprising given that it is perhaps the most interesting and surprising idea so far proposed. It would seem that the animal is actually…. a flying squirrel. Despite the fact that it’s only just becoming well known, this theory has been around since March 2006, when Andrew Kitchener published an article on Erik Meijaard’s thoughts about the creature (Kitchener 2006). Both authors are noted mammalogists. Meijaard observed that the creature seems to have ‘the suggestion of a membrane between the front and hind limbs’. I agree, and had always wondered why the animal seemed to have such a deep ‘belly’.

In fact the case for the squirrel identity is strong: by tabulating all the morphological features present in the two photos, and then doing likewise for all 16 similar-sized mammals from Borneo (they included one Sulawesi viverrid too), Meijaard et al. (2006) showed that the Kayan Mentarang animal agrees well in recordable details with two flying squirrels found on Borneo: Thomas’ flying squirrel Aeromys thomasi and the Red giant flying squirrel Petaurista petaurista (taxiderm specimen shown at left, close-up head shot at top of article, and painting shown at bottom of article. Sorry, no picture of A. thomasi to hand). Of the 13 morphological characters available for comparison, A. thomasi matches the Kayan Mentarang animal in 12 of them (the 13th character – orientation of the tail when on the ground – remains uncertain in A. thomasi). In contrast to viverrids, mongooses, linsangs, mustelids, the Bornean bay cat, the Groove-toothed squirrel (aka Tufted ground squirrel) Rheithosciurus macrotis, and various primates, only A. thomasi agrees with the Kayan Mentarang animal in having a short face, small, rounded ears, a reddish non-patterned coat, a tail that exceeds head and body length, and a rounded tail tip. The two also agree in size (the Kayan Mentarang animal is estimated to be 350-450 mm in head and body length) and limb proportions.

When the two ‘mystery’ photos are looked at with all of this in mind we see, with hindsight I suppose, hitherto unappreciated squirreley-ness. The way the animal holds its long hindlimbs (referring here to the photo showing the animal from behind) and the suggestion of a patagium now make sense, and the unusual curving shape of the long tail matches the tail posture reported for giant flying squirrels (Meijaard et al. 2006, p. 321) and is unlike that of viverrids and other carnivorans. The white eye-shine present in the Kayan Mentarang animal reportedly matches that of flying squirrels, ‘whereas the civets and cats normally have less bright, yellowish or orange eye-shine’ (Meijaard et al. 2006, p. 321). Look at the image at the top of the article: I’m not too sure about this. To help convince people, Meijaard et al. (2006) have provided two paintings of the Kayan Mentarang animal, this time ‘reconstructed’ using A. thomasi to fill in the gaps.

If Meijaard et al. (2006) are correct, then two factors have helped obscure the animal’s true identity. Firstly, there is the frustrating fact that its face is obscured by some vegetation, or, as WWF’s Head of Borneo programme director Stuart Chapman put it, ‘As with all good yeti shots, there is a leaf that obscures its snout’ (Fair 2006). I don’t quite understand the yeti reference, as there aren’t any photos of purported yetis that have leaves in the way… but, then, there aren’t any good yeti photos at all :) (maybe he was thinking of the Myakka skunk ape photos?). If this really is a squirrel, we would surely all have realised sooner had we been able to see its pointed, distinctively rodent-type snout. Secondly, people just aren’t used to seeing flying squirrels walking around on the ground, which isn’t surprising given that forest-dwelling flying squirrels are arboreal animals of the canopy. It stands to reason that a ground-walking flying squirrel looked unfamiliar, even to Bornean locals with good knowledge of wildlife, and to experienced field biologists.

Of course none of this demonstrates that the Kayan Mentarang animal really is a ground-walking specimen of A. thomasi, and not an unknown species. But I’d say that the case is very good and more likely than the new species hypothesis.

Given that giant flying squirrels are awesome and deeply weird I’m no less impressed by the Kayan Mentarang animal than I was when I thought it likely to be an unusual new viverrid. Some species of Petaurista truly are giants (for squirrels), reaching 2.5 kg and more than 100 cm in total length. Though experts at manoeuvrable gliding, they might undergo periods of occasional flightlessness when, in Spring, they gorge on buds and new leaves.

As has been noted by both John Lynch and Loren Coleman, of incidental interest in this story is that the squirrel A. thomasi was described by Sir Charles Hose (1863-1929) in 1900*, while the civet D. hosei was described by Michael Rogers Oldfield Thomas (1858-1929) in 1892. I also like the fact that Meijaard et al. submitted their paper on April 1st… so far as I can tell this didn’t delay its eventual publication however (woe betide forgetful authors who submit papers announcing bizarre results on April 1st, as Charles Paxton will attest). Note also that I wasn’t planning to blog on the Kayan Mentarang animal so soon, but after John Lynch wrote about it at Stranger Fruit on New Year’s Day (go here) I figured that it was only a matter of time before it become old news. For proof that I’ve been planning to post about the Kayan Mentarang since 2006, look at the last paragraph here.. ha, as if proof were needed.

* Entirely by coincidence, I recently wrote about Hose in the Baikal seal post. I’ve also written about Meijaard’s research before: see The many babirusa species.

And that is that. I just finished writing an article on those green lizards from Bournemouth and have lately been deeply immersed in literature on European herpetofauna. More details soon. Oh, and for the latest news on Tetrapod Zoology please go here.

Refs - -

Chapron, G., Veron, G. & Jennings, A. 2006. New carnivore species in Borneo may not be new. Oryx 40, 138.

Dinets, V. 2003. Records of small carnivores from Mount Kinabalu, Sabah. Small Carnivore Conservation 28, 9.

Fair, J. 2006. Scientists foxed by new carnivore. BBC Wildlife 24 (1), 30.

Francis, C. M. 2002. An observation of Hose’s civet in Brunei. Small Carnivore Conservation 26, 16.

Kitchener, A. 2006. Mystery beast revealed. BBC Wildlife 24 (3), 29.

Meijaard, E., Kitchener, A. C. & Smeenk, C. 2006. ‘New Bornean carnivore’ is most likely a little known flying squirrel. Mammal Review 36, 318-324.

Shuker, K. P. N. 2006. Mystery beast in Borneo. Fortean Times 206, 4.

Wells, K., Biun, A. & Gabin, M. 2005. Viverrid and herpestid observations by camera and small mamal cage trapping in the lowland rainforests on Borneo including a record of Hose’s civet, Diplogale hosei. Small Carnivore Conservation 32, 12-14.

That’s no mystery carnivore (part I)

2007-01-03T20:24:00.000Z

If I were to produce a list of the 100 most exciting discoveries made in tetrapod zoology within the last few years (which I won’t), then up there in the top 20 - at least - would be the Kayan Mentarang animal. Or, in fact, it would have been up there in the top 20 (at least) for, as we’ll see, a new study has demoted somewhat the potential significance of this creature. You’re doubtless already familiar with it (even if the name Kayan Mentarang doesn’t sound familiar): it’s that unusual reddish long-tailed mammal, photographed by a team from the Swiss World Wildlife Fund at a camera-trap in central Borneo, and widely hailed as a probable new species. If you’re wondering, ‘Kayan Mentarang animal’ is not this creature’s official name: it’s a label that I’ve invented, and one that (in my opinion) is clearly superior to the various other labels that have already been given to the creature. Some writers have referred to it as a cat-fox, while one newspaper article jokingly suggested that it be termed the ‘cat-dog-fox-monkey-lemur’.

Though the two photos that feature the Kayan Mentarang animal were taken in 2003, they were not made public until early December 2005 (the second photo, showing the animal from behind, is featured at left). I don’t know why this postponement occurred, but such delays are fairly ordinary given that scientists are often really, really busy, or hesitant to announce controversial news. Then again, some news is deliberately held back until its release might have the most impact. I don’t want to seem cynical so will stop there, but it’s probably not a coincidence that the discovery was announced at the same time as was news that the Indonesian Government plans to start an oil palm plantation in the vicinity of Kayan Mentarang National Park.

During December 2005 and January and February 2006 features on the Kayan Mentarang animal appeared in most newspapers, in most science magazines, in Science (Holden 2005), and on TV. Led by Stephen Wulffraat, the WWF team confirmed that local people were unaware of the creature, and they also noted that none of the mammalogists they’d consulted had been able to identify it. While some biologists noted a vague superficial similarity with lemurs, most concluded that it was a viverrid: a member of the same carnivoran family as civets and genets*. Many viverrid species are highly enigmatic and several have only recently been discovered, have only occasionally been photographed alive, or have even not been photographed alive at all (for a nice review see Schreiber 1989).

* Though note that recent phylogenetic studies have agreed that the traditional Viverridae is not monophyletic. Nandinia is not close to civets and genets, but is in fact a basal feliformian (Flynn et al. 2005); oriental linsangs (Prionodon) are not viverrids, but in fact the sister-taxon to cats (Gaubert & Cordeiro-Estrela 2006, Gaubert & Veron 2003); and Madagascan carnivorans are also not viverrids, but closer to mongooses (Gaubert et al. 2005).

Thanks to its long tail, gracile proportions, size (comparable to that of a house cat), and general civet-like appearance, the Kayan Mentarang animal soon became widely regarded as a probable new viverrid. The adjacent painting is a widely-reproduced image, produced by Wahyu Gumelar for WWF Indonesia, depicting the animal as a new, hitherto unknown viverrid. The idea that the Kayan Mentarang animal might be a hitherto-undiscovered species is exciting and easy to take seriously, given the size of Borneo (third biggest island) and the continuing discovery there of many new species. However, some authors were prepared to go further and be even more precise in their identification, and by far the most popular and widely reported identification has been that the Kayan Mentarang animal in fact represented a known species of viverrid: namely, Hose’s civet Diplogale hosei (also known as Hose’s palm civet or the Brown musang) [see image below]. Named in 1892 and known from less than 20 specimens, this is a poorly known terrestrial viverrid of montane forests, and good observations and photos of it are few and far between.

Arguing that the Kayan Mentarang animal and Hose’s civet were anatomically similar, Chapron et al. (2006) proposed that the alleged new carnivore ‘may not be new’. They clearly weren’t entirely convinced by their own explanation however, as they also noted that the Borneo bay cat Catopuma badia (another highly elusive carnivoran: named in 1874, it appeared extinct during the 1980s but was rediscovered in 1992) might also be the true identity of the cryptic creature. Identification of the Kayan Mentarang animal as Hose’s civet was also preferred by some cryptozoologists (Loren Coleman blogged about this at cryptomundo: go here).

Sorry, have to stop there. Part II to be posted soon… Lots more on Hose’s civet, and also ‘the reveal’. And if you know the answer (i.e., you’ve read Erik Meijaard et al.’s paper, or you’ve been clever enough to do a bit of surfing and have found the answer on other blogs and news sites), then don’t spoil it for everyone else :)

Oh yeah: happy new year!

Refs - -

Chapron, G., Veron, G. & Jennings, A. 2006. New carnivore species in Borneo may not be new. Oryx 40, 138.

Flynn, J. J., Finarelli, J. A., Zehr, S., Hsu, J. & Nedbal, M. A. 2005. Molecular phylogeny of the Carnivora (Mammalia): assessing the impact of increased sampling on resolving enigmatic relationships. Systematic Biology 54, 317-337.

Gaubert, P. & Cordeiro-Estrela, P. 2006. Phylogenetic systematics and tempo of evolution of the Viverrinae (Mammalia, Carnivora, Viverridae) within feliformians: implications for faunal exchange between Asia and Africa. Molecular Phylogenetics and Evolution 41, 266-278.

- . & Veron, G. 2003. Exhaustive sample set among Viverridae reveals the sister-group of felids: the linsangs as a case of extreme morphological convergence within Feliformia. Proceedings of the Royal Society of London B 270, 2523-2530.

- ., Wozencraft, W. C., Cordeiro-Estrela, P. & Veron, G. 2005. Mosaics of convergences and noise in morphological phylogenies: what’s in a viverrid-like carnivoran? Systematic Biology 54, 865-894.

Holden, C. 2005. New species in Borneo? Science 310, 1764

Schreiber, A. 1989. Mysterious mustelids, very mysterious viverrids. BBC Wildlife 7 (12), 816-823.

When eagles go bad, one more time... part II

2006-12-30T12:26:00.000Z

Oh, and just for those who still don't accept the idea that a Golden eagle can kill a wolf...

Image again courtesy of Steve Bodio: for more see his post on wolf-killing eagles in Kazakhstan.

The

Kirghiz

tribesmen of central Asia have long been known to use Golden eagles to catch wolves, and in fact Marco Polo (c. 1254-1324) wrote of ‘a great number of eagles, all trained to catch wolves, foxes, deer and wild goats’. This would have been some time in the 1270s, when Polo was in his twenties. John Love, in his 1989 book on eagles, wrote of a Kirghizian eagle that had captured 14 wolves in a day. A Kirghizian wolf-hunting eagle was termed a berkut, and there is some disagreement as to what a berkut’s role was in wolf-killing.

Some authors state that the eagle’s job was not to kill the wolf, but to hold it down until its trainer was able to arrive (on horseback) and dispatch the wolf with a knife. However, as is illustrated by the fact that Golden eagles can kill mammals bigger and heavier than wolves by a powerful strike directed at the back of the skull (go here), a trained eagle would in fact be able to kill even an adult wolf if it approached quickly enough and struck the wolf, from behind, in the right place. Accordingly, other authors state that the berkut’s role was to kill – rather than just pin down – the wolf. Wikipedia’s entry on this subject states that ‘These eagles are so fast and powerful that they are capable of killing a fully grown wolf by diving at speed and striking the wolf on the back of the head or neck’.

Some wolves proved particularly challenging quarry, however, and there is the tale of one that foiled the attempts of 11 eagles – killing each one – until it was finally dispatched thanks to the efforts of a twelfth eagle. Love (1989) intimated that wolf-hunting with eagles is all but extinct in modern times but, as you can see from Steve’s blog post alluded to above, and from his 2003 book Eagle Dreams: Searching for Legends in Wild Mongolia, this is certainly not true.

Oh, and while I’m here: check out the recent discovery of a female Golden eagle from Buffalo Valley, Wyoming (NOT New York as I said previously!), captured by Bryan Bedrosian and colleagues, that apparently weighed at least 7.7 kg. This wouldn’t be the biggest Golden eagle ever - that record goes to a 9 kg Spanish female (though I don’t know if this size was ever authenticated and must find out) - but it would be a record for North America.

To those who check the blog regularly, you’ll note that this post has just been updated. I should note that I add updates, where relevant, to various of the posts. For other recent examples see ‘Time wandering’ cynodonts and The first new mammal in 100 years?.

Ref - -

Love, J. A. 1989. Eagles. Whittet Books, London.

When eagles go bad, one more time

2006-12-29T21:42:00.000Z

A little Christmas season/New Year’s present for all my regular readers. The second article ever posted to this blog discussed the fact (note: FACT) that big eagles, most notably the Golden eagle Aquila chrysaetos, are able to attack and kill mammals substantially bigger than they are (go here). Wild individuals will attack and kill deer (including reindeer, roe deer and white-tailed deer) and pronghorn, and there are ridiculous, authenticated cases where Golden eagles have killed domestic calves exceeding 100 kg in weight. Trained individuals in

Kazakhstan

kill wolves.

I note that those who are ultra-sceptical of the idea that a 6 kg eagle might be able to kill a 30 kg wolf, or a 100 kg baby cow, are never even aware of any of this stuff, let alone familiar with it. Incidentally, I have tried for a while to get TV companies interested in this issue (and in other arcane, fascinating aspects of tetrapod zoology), thus far without any success. In fact I’ll come clean now and tell you that I spent some considerable time during 2006 trying to get various television companies to do some sort of TV spin-off of this blog site. I had in mind something along the lines of Mark O’Shea’s excellent series on dangerous reptiles, and I did actually get quite some interest, but evidently not enough.

Anyway, while surfing recently I noticed Birdchick’s two posts (two links there) devoted to this issue. She was particularly interested in the awesome image shown at top, but had some concerns about its authenticity. I was first sent this image by Steve Bodio of Querencia, and have since used it to death in powerpoint presentations and so on (in my recent ‘Evolution and diversity of the tetrapods’ course I used it as the opening slide). It shows a Golden eagle attacking a Red fox Vulpes vulpes (not a coyote or other canid as some people have suggested) and was taken in Finland in February 2006 by wildlife photographer Pekka Komi of tarsiger.com. Steve first discussed this image here. While a lot of people have seen the best image (the one at top), less appreciated is that it’s part of a series, five of which are posted on the site (go here). We see the two predators confronting each other at a carcass, with the eagle eventually winning the conflict, kicking the crap out of the fox, and the fox then running away. It is not an attempt at predation, and in fact the carcass had been specially laid out to attract raptors.

The fact that the image is part of a sequence of course rules out the whole issue of the best image being mocked-up, and to be honest this thought never occurred to me given that I’m familiar with the idea that a big eagle is well able to tackle a fox. If that seems like a strange or radical idea, then I can understand that the image might be difficult to accept at face value. The trump card is an exciting video clip (from youtube) viewable here on Birdchick’s site: it shows a Golden eagle attacking a fox, though it’s not possible to work out how the whole event ended.

Many thanks to Steve for the supplementary info. This time I will state with confidence that this post is going to be the last one for 2006, and it is kind of ironic, yet satisfactory, that I have figuratively gone full circle, and have ended the year by discussing one of the year’s first blog articles (indeed, one of my first blog articles ever). I can confidently state that something about my blogging will be different in 2007, but as for what that is… you’ll have to wait and see [UPDATE: to see what I was getting at, go here].

Happy Christmas, from gigantic Spanish sauropods... or, alas, poor ‘Angloposeidon’

2006-12-23T12:22:00.000Z

I said the last post would likely be the last before 2007. I lied, as while checking my emails this morning, something came up that I just can’t resist commenting on. As regular blog-readers will know, back in 2004 I and colleagues described a large cervical vertebra from an Isle of Wight sauropod dinosaur (see ‘Angloposeidon’, the unreported story: part I, part II, part III and part IV). Belonging to a large brachiosaurid closely related to the Upper Jurassic Brachiosaurus and Lower Cretaceous Sauroposeidon, the Isle of Wight specimen is 745 mm long, which suggests a total length exceeding 20 m. That made it the largest published European dinosaur (Naish et al. 2004). However, when the time came to talk to journalists about the discovery, I mentioned on several occasions the fact that even bigger European dinosaurs were due to the published in the near future. As I said in part IV…

During the long period of time in which the [‘Angloposeidon’] manuscript was in preparation I spoke to several European colleagues who told me of new sauropods from Portugal and Spain that would easily outclass MIWG.7306 in terms of size. I had this on my mind all the way through the submission process, and at any time I expected there to be some report of a new European sauropod that had a total length exceeding 30 m. But even today such discoveries have yet to materialise, and having now seen some of the specimens in question I know that they fail to come close to the 20 m + estimated for MIWG.7306.

The news, of course, is that one of these Iberian giants has just been published (Royo-Torres et al. 2006): it’s the new taxon Turiasaurus riodevensis from the Villar del Arzobispo Formation (Jurassic-Cretaceus boundary) of Riodeva (Teruel Province, Spain) [many thanks to those who have sent the pdf!]. And it doesn’t fail to meet the hype: it really is immense (so, the other Iberian giants that I’ve seen were mere pretenders). Turiasaurus has a humerus about 1.8 m long and an estimated weight of over 40 tons. This makes it quite bigger than ‘Angloposeidon’ and in fact one of the biggest sauropods in the world, almost on par with immense titanosaurs like Argentinosaurus and Paralititan. Furthermore, phylogenetic analysis indicates that Turiasaurus belongs to a new clade located close to the origin of Neosauropoda (the macronarian-diplodocoid clade). Galveosaurus (named in 2005, and previously regarded as a cetiosaurid*) and Losillasaurus (named in 2001 and regarded as a diplodocoid, but since suggested to be a mamenchisaurid**) also seem to be turiasaurians. That’s pretty interesting, though it has to be said that the statistical support for turiasaurian monophyly is not overwhelmingly impressive.

* And later renamed Galvesaurus by a different group of authors. I will cover the Galveosaurus-Galvesaurus issue some time in the future.

** The correct term for the group dubbed ‘omeisaurids’ by some.

Furthermore, the fact that Turiasaurus is represented by good, associated remains means that it might help clear up some of the mess represented by isolated remains (see previous post: Obscure dinosaurs of the Kimmeridge Clay). Scattered throughout the European Jurassic and Cretaceous record are assorted sauropod teeth that roughly resemble the teeth of better known forms, such as camarasaurs and brachiosaurids, but also have a unique look about them. Examples include the huge, beautifully preserved tooth named Oplosaurus armatus (from the Isle of Wight*) and the unusual specimen Cardiodon rugulosus from the Middle Jurassic Forest Marble Formation of Bradford-on-Avon, Wiltshire. It now turns out that these teeth are similar to those of Turiasaurus, which raises the interesting possibility that they are further representatives of this newly-recognised group. That would be cool.

* For more on Oplosaurus and other Lower Cretaceous English sauropods go here.

Anyway, I’ll have more to say on turiasaurians and other Iberian sauropods in the future. And it really is relevant as I and colleagues (Barbara Sánchez-Hernández and Mike Benton) currently have an article in press on dinosaurs (including sauropods) from the Villar del Arzobispo Formation. Maybe some of the material we have belongs to Turiasaurus? We’ll see...

Finally, in other dinosaur news, you’ll note from the big picture above that Tom Holtz’s big dinosaur encyclopedia is finally being advertised. I discussed it previously here.

All the best for Christmas and the New Year. My new year’s resolution? To finish writing all those blog posts I’ve been promising for the last year. Controversial mammals from Borneo, the passerine supertree, rhinogradentians, giant Australian feral cats, temnospondyls, more on tupuxuarids, agamas and sea snakes, the biggest slow worms, fake Chinese turtles, amphisbaenians, and loads more on sauropods, theropods, pneumaticity, flightless birds, bizarre pterosaurs, and giant eagles. And keep an eye on Tetrapod Zoology’s 1st Birthday... Goodbye 2006!

Refs - -

Naish, D., Martill, D. M., Cooper, D. & Stevens, K. A. 2004. Europe’s largest dinosaur? A giant brachiosaurid cervical vertebra from the Wessex Formation (Early Cretaceous) of southern England. Cretaceous Research 25, 787-795.

Royo-Torres, R., Cobos, A. & Alcala, L. 2006. A giant European dinosaur and a new sauropod clade. Science 314, 1925-1927.

Obscure dinosaurs of the Kimmeridge Clay

2006-12-19T21:17:00.000Z

Someone – I forget who it was – once described dinosaurs as ‘the most American animals that ever lived’. Well, with all due respect to North America’s endemic dinosaurs (Tyrannosaurus, Triceratops and so on), and to the worthy history of North American palaeontological discoveries, this is crap. Dinosaurs are no more American than they are Patagonian, Nigerian or French. Or at least that’s the politically correct version. Reality is rather different: dinosaurs are in fact British, and – what’s more – specifically English, having been discovered in England by English scientists working on English fossils. Ok, lest some flag-waving patriot of any nation gets offended by this, let me assure you that this is all tongue-in-cheek and not to be taken seriously. Dinosaurs no more ‘belong’ to any country than do rodents or grasshoppers.

England has a rich dinosaur record, and many of the taxa first named from English rocks (e.g., Hypsilophodon, Cetiosaurus, Baryonyx) have proved globally important in terms of what they’ve told us about dinosaur evolution and diversity. Furthermore, these taxa and others (e.g., Scelidosaurus, Mantellisaurus, Neovenator) are represented by excellent remains that sometimes consist of near-complete skeletons. Also noteworthy is that English dinosaurs span most of the Mesozoic, from the Upper Triassic to about the middle of the Cretaceous (there is no dinosaur-bearing Upper Cretaceous in England). So as a gross generalisation of the worse kind, England’s dinosaur record is ‘good’.

Partly because the study of dinosaurs began in England, there is an extensive and voluminous literature on scrappy English dinosaur fossils. Furthermore, these early finds were usually given binomial names, but as our knowledge of these animals has improved, it is understandable that many of these remains are today considered inadequate in terms of establishing taxonomic validity. Ideas on British taxa were sometimes revised several or many times as knowledge improved, and the results are convoluted synonymy lists. As I’ve now mentioned several times on this blog, a major effort to review this mess has recently been produced by Dave Martill and myself, and is currently in press for a special bicentennial issue of Journal of the Geological Society. More on that when it appears. In an unrelated project, Dave, I and Sarah Fielding recently reviewed the English dinosaurs of the Kimmeridge Clay Formation, and as it’s only recently been published (Martill et al. 2006) I figured I may as well blog about it.

The Kimmeridge Clay

The Kimmeridge Clay Formation is an Upper Jurassic mudrock, deposited within a shallow marine environment, that crops out in a narrow strip from Dorset in the south-west to Yorkshire in the north-east. There are also a few outcrops in Scotland, and a contemporaneous equivalent that crops out in northern France. Like the older Oxford Clay Formation (go see Life in the Oxford Clay sea), the Kimmeridge Clay has yielded numerous ichthyosaurs, plesiosaurs, marine crocodyliforms and fish. Excepting the fish of course, those animals are all very interesting and worthy of discussion, but of more interest right now are the many dinosaurs that have also been discovered in the Kimmeridge Clay.

Why have so many dinosaurs been recovered from a geological unit deposited in a shallow sea? Despite the title of our paper, I don’t think this means much. The dinosaurs we find in these marine rocks don’t exhibit any features suggesting that they were aquatic or amphibious, and it appears most likely that the carcasses of the relevant species were washed out to sea on a fairly regular basis. This is well supported by the fact that other fossils, such as plants, and the sediments themselves, have clearly been derived from terrestrial sources. At a time when shallow seas covered the better part of the European continent, it makes sense that an unusually high number of terrestrial animals living on the archipelagos of the region found their way into the marine environment.

Kimmeridge Clay dinosaurs belong to most of the major groups living in Europe during the Upper Jurassic. There were large and small theropods, several types of sauropod, herbivorous ornithopods, and both stegosaurs and ankylosaurs.

Kimmeridge Clay sauropods

Perhaps the most interesting of the Kimmeridge Clay sauropods was named by John Whittaker Hulke* in 1874. Based only on a big humerus (1.3 m long, though perhaps 1.7 m long when complete: see adjacent image) discovered at Weymouth, Hulke named it Ceteosaurus humero-cristatus: note that he used a spelling of the generic name that later fell out of favour (the original, and thus favoured, spelling is Cetiosaurus), and used a hyphen in the specific name (an action that is illegal under today’s nomenclatural rules). This animal is quite certainly not really a species of Cetiosaurus (hence the quote marks used from hereon), as it is highly different in detail from the humerus of Cetiosaurus oxoniensis, the type species of the genus (well, actually, C. oxoniensis is not yet the type species of the genus, but that’s a long and complex issue that I can’t go into right now). So what is it? Its length, slender proportions and particularly prominent deltopectoral crest show that it is a brachiosaurid and, among brachiosaurids, its particularly long deltopectoral crest makes it unique and diagnosable. ‘C.’ humerocristatus is therefore one of those annoying fossil tetrapods that clearly needs a new name. So why doesn’t it have one?

The problem is that most workers who encounter problems like this prefer to err on the side of hyper-conservatism (Peter Dodson’s advice is that ‘the practise of naming genera on [the basis of isolated remains] is a highly undesirable one, greatly to be discouraged’ (Dodson 1996, p. 240): for more on this subject see Cryptic dinosaur diversity). Some therefore opt not to name something that they themselves have said deserves a name. In their review of sauropod species referred to Cetiosaurus, Upchurch & Martin (2003) concluded that ‘C.’ humerocristatus ‘is regarded as a distinct taxon referable to the Brachiosauridae’ but went on to state that ‘[w]e prefer to wait for more complete material before proposing a new name for this taxon’ (p. 213). Similarly, Upchurch et al. (2004) regarded ‘C.’ humerocristatus as ‘a potentially distinct taxon … [but] it would be unsafe to erect a new generic name given the material available’ (p. 309). This perpetuates the cycle, and the taxon goes unnamed for even longer.

I’m equally as guilty of this as are Upchurch and Martin: in an earlier draft of the Kimmeridge Clay manuscript, my co-authors did actually come up with a new generic name for ‘C.’ humerocristatus (it has to be said, a pretty awful one), but I managed to get it removed. While I think it would be useful if this apparently diagnostic brachiosaur were named, I guess I’m bowing to peer pressure. Presumably, ‘C.’ humerocristatus was built much like better-known brachiosaurids (such as Brachiosaurus: adjacent image is Greg Paul’s old restoration of Brachiosaurus with Ceratosaurus and pterosaurs), but it was surely different in various of its details. A few additional bones have been suggested to belong to it, but there’s no way of knowing whether these really do belong to the same animal as the diagnostic humerus.

* One of the most prolific dinosaur workers in England during the latter half of the 19^th century, Hulke (1830-1895) was a renowned ophthalmologist and firm ally of Huxley. Elected Fellow of the Geological Society of London in 1868, he was President by 1887 and, later, Foreign Secretary. Hulke was elected to the Royal Society for his work on the retina and received the Wollaston Medal in 1887. Research on prehistoric reptiles was only his hobby, but he published multiple papers on them, with 25 appearing in the Quarterly Journal of the Geological Society of London alone.

Various other sauropod remains have been reported from the Kimmeridge Clay. ‘Ornithopsis’ manseli was named in 1888 for another isolated humerus, and again it appears to be from a brachiosaurid. In fact it might be the same animal as ‘C.’ humerocristatus. Yet again it was originally placed in an inappropriate genus: Ornithopsis is a Lower Cretaceous sauropod (first named for dorsal vertebrae), and there’s no reason at all to think that an Upper Jurassic humerus should be referred to a genus based on Cretaceous vertebrae.

Then there’s Bothriospondylus suffossus, based on vertebrae. Often regarded as a brachiosaurid, its remains are not diagnostic, nor is there any reason to think that they belong to a brachiosaurid, nor even to a macronarian (Macronaria is the sauropod clade that includes brachiosaurids and titanosaurs). Because Bothriospondylus was named early in the scientific discovery of sauropods (in 1875), it quickly became a sort of ‘waste-basket’ taxon to which sauropod remains from all over the world were referred. Thus, various Cretaceous sauropod remains from England, as well as remains from the Middle Jurassic of Madagascar and the Upper Jurassic of France, have been identified (erroneously) as Bothriospondylus. Incidentally, the specific name of the type species of this genus is conventionally spelt incorrectly, with it usually being written ‘suffosus’. On naming the species in 1875, Richard Owen used both double f and double s, but most authors seem to have missed this for some reason.

Kimmeridge Clay theropods

Only a few theropods (predatory dinosaurs) have been reported from the Kimmeridge Clay, and two of them are particularly interesting. The first is interesting because it’s both reasonably well represented (its remains include vertebrae from all parts of the column, pelvic and hind-limb elements), and something new. It’s some kind of peculiar, gracile tetanuran, and is due to be studied as part of a larger project on Jurassic theropods.

The second specimen is considerably less impressive, consisting only of two phalanges from the foot. Discovered at Fleet in Dorset, they are presently part of a private collection. What makes them particularly interesting is the fact that they’ve been identified as belong to an ornithomimid (Brokenshire & Clarke 1993): a theropod clade (often known as ostrich dinosaurs) otherwise restricted to the Cretaceous. If the identification is correct, the history of this group would be extended considerably. However, an identification this precise, given that the material consists only of worn, isolated toe bones, is problematic and there is little reason to think that it is correct. The bones do superficially resemble the toe bones of ornithomimids, but they superficially resemble the toe bones of many other theropods as well. Consequently they are better identified as Theropoda indet. (Martill et al. 2006).

That’ll do for now. Of course there are also the ornithischians: anachronistic ornithopods and pliosaur chew-toys. More on them in the near future. Remember to keep checking for new Chri stmas cards. Seasons greetings to all - I don’t think I’ll get the chance to do any blogging between now and the new year.

A pdf of Martill et al. (2006) is available should anyone want it (email me: eotyrannus at gmail dot com).

For the latest news on Tetrapod Zoology do go here.

Refs - -

Brokenshire, A. J. and Clarke, J. B. 1993. Important recently collected dinosaurian remains from the Lower Kimmeridge Clay at Weymouth. Proceedings of the Dorset Natural History and Archaeological Society 115, 177-178.

Dodson, P. 1996. The Horned Dinosaurs. Princeton University Press, Princeton, NJ.

Martill, D. M., Naish, D. & Earland, S. 2006. Dinosaurs in marine strata: evidence from the British Jurassic, including a review of the allochthonous vertebrate assemblage from the marine Kimmeridge Clay Formation (Upper Jurassic) of Great Britain. In Colectivo Arqueológico-Paleontológico Salense (ed) Actas de las III Jornadas sobre Dinosaurios y su Entorno. Salas de los Infantes (Burgos, España), pp. 47-83.

Upchurch, P., Barrett, P. M. & Dodson, P. 2004. Sauropoda. In Weishampel, D. B., Dodson, P. & Osmólska, H. (eds) The Dinosauria, Second Edition. University of California Press (Berkeley), pp. 259-322.

- . & Martin, J. 2003. The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology 23, 208-231.

Matt Wedel: officially, a bastard

2006-12-18T23:56:00.000Z

I really should stop talking to other people qualified in vertebrate palaeontology. It’s so bloody depressing. “I’m working on this”, “I’m writing about that”, “Oh, and did I mention the award I won?”. Yes, I am very pleased to congratulate my good friend Matt Wedel – whom you may or may not know better as Dr Vector, or as ‘that pneumaticity guy’ (shown here posing with an enormous bone*) – for winning the 2006 International Award on Paleontology. The award stems from his excellent 2005 paper ‘Postcranial skeletal pneumaticity in sauropods and its implications for mass estimates’: required reading here at Tetrapod Zoology Towers (free pdf available here). Well done Matt. Bastard.

* Oh alright, it’s an apatosaurine vertebra.

Kimmeridge Clay dinosaurs post to follow soon, once other assorted crap is out of the way. For the latest news on Tetrapod Zoology do go here.

Christmas cards

2006-12-16T00:58:00.000Z

Some say that the people involved in palaeontology are all a bit mad. Of course, I don't know whether this is true or not, but - on a completely unrelated note - here are some of the Christmas e-cards that are winging their way around cyberspace right now. Because I can't get the pictures into the exact configuration I have in mind (despite copious mucking around with the html) I'm having to shrink them right down, so please click to enlarge (do we ever really need to say this?).

My card is the big one at the top (and, yes, that IS a hellboy reference). I just showed it to Toni (my wife). "Oh", she said. The enigmatic one featuring the vertebra is from sauropod worker Mike P. Taylor; the festive dromaeosaur is from (... who else) Luis Rey; the hat-wearing Mantellisaurus is from Simon Clabby (Mantellisaurus is the iguanodont dinosaur formerly known as Iguanodon atherfieldensis. It was finally given its own genus by Greg Paul this year: I am fairly confident that this is its first appearance on a Christmas card). The vertebra on Mike's card is a particularly interesting one and has been sort of alluded to in a previous post (see Lots of sauropods). Rest assured I will have a lot more to say about it in the near future.

The image at left is from Mark Witton. An earlier version was first seen here on Mark's flickr site - he didn't send me a copy (sob, the rejection: maybe this is because I still owe him comments on a pterosaur manuscript we're supposedly collaborating on), so I initially nicked... err, borrowed it. I needn't have worried, as I later received a personally emailed version: it's different from the older version, and is the version shown here. Anyway, it features everyone's favourite pterosaur: that ridiculous antlered nyctosaur described by Chris Bennett (2003). Note the fact that Mark depicts the posterior prong of the crest as far longer than is normally shown. Why? Because this is apparently correct, that's why. I'm going to be blogging about nyctosaurs soon, by the way, as I've recently done reading the Muzquizopteryx paper.

Next we have a most worthy contribution from he of dead fishes fame, my huge pal Graeme Elliott. It's a very nicely done composite of student still life, cutting-edge computer wizardly, outstanding humour, and giant robot dinosaurs. The odd creature at far right (it's wearing lots of denim) is owl specialist Richard Hing. Again, I borrowed the image from Graeme's flickr site (go here)... in fact, Graeme has produced a second Christmas image featuring what might be a cryptid, the elusive black dog of Bickwell (go here). I found it hilarious. Anyway, I'll add further cards to this post as and when they arrive.

Kimmeridge Clay dinosaurs coming next (update: I lied), though the possibility remains that a certain mysterious Bornean mammal might get covered instead... For the latest news on Tetrapod Zoology do go here.

Ref - -

Bennett, S. C. 2003. New crested specimens of the Late Cretaceous pterosaur Nyctosaurus. Paläontologische Zeitschrift 77, 61-75.

The most inconvenient seal

2006-12-12T21:57:00.000Z

These are exciting times, if you’re into uber-nerdy zoological discoveries. At long long last,

New Zealand

’s Miocene fossil mammals have finally been published. Not only do these fossils show that terrestrial mammals were formerly present on

New Zealand

, they are remarkable in apparently belonging to an animal that must have diverged during the Cretaceous. If you’re wondering: yes, this is the fossil that inspired my previous posts on late-surviving non-mammalian synapsids (here and here). And also on Mesozoic mammals we have the amazing new gliding mammal Volaticotherium [image at left] from the controversial Daohugou beds of Inner Mongolia. Other neat recent discoveries – from the Cretaceous – include the new Mongolian dromaeosaur Tsaagan mangas and the (allegedly) flightless enantiornithean Elsornis keni. I’ll blog about all of these things, time permitting (famous last words).

On the subject of fossils, a major personal event occurred today, and it involves SVP (the Society of Vertebrate Paleontology). To whom it concerns: thank you, sincerely. Anyway, moving on: what about those goddam seals?

One of the most asked about questions I’ve encountered in tetrapod zoology concerns the mysterious seals of Siberia’s Lake Baikal. Everyone knows that an endemic, particularly small species of land-locked freshwater seal lives there, but nobody really knows how it got there. Less well known is that it isn’t the only lake-dwelling seal in the world: there are populations of Ringed seals Phoca hispida in Lake Saimaa (P. h. saimensis) and Lake Ladoga (P. h. ladogensis) in Fennoscandia, there is the Caspian seal P. caspica, and there are freshwater populations of the Common or Harbour seal P. vitulina in the Lacs des Loups Marins of northern Quebec, and in Alaska’s Lake Iliamna (Smith et al. 1996). Furthermore, Ringed seals became isolated in the Baltic Sea about 12,500 years ago when the connection with the North Sea closed due to glaciation, and effectively found themselves in a giant enclosed inland lake. I was planning to discuss these other forms, but have run out of space and time.

First named by Johann Friedrich Gmelin (1748-1804) in 1788*, the Baikal seal (also known as the Nerpa) was mentioned in print as early as 1763. Much exploited by local people for its meat and pelt, it was seriously reduced in numbers during the 1930s, and during the 1970s 2-3000 pups were being harvested each year for their skins. Bonner (1994) later gave higher numbers of 5-6000, implying that harvest numbers have increased within recent decades. A survey performed in 2000 revealed the presence of about 85,000 seals in total, and their numbers are reported to be falling as increasing numbers of pups are being killed.

* Incidentally, Gmelin thought that Baikal seals were just a form of Common seal, and not a distinct species.

Outbreaks of canine distemper virus resulted in the deaths of about 5000 Baikal seals during 1987-88, and it is inferred that the seals were infected by domestic dogs at some stage (Kennedy et al. 2000). Exactly how this happened is not clear, though canine distemper has also caused die-offs in Antarctic Crabeater seals Lobodon carcinophagus and other pinnipeds. This problem has afflicted Asia’s other land-locked seal, the Caspian seal. Between April and May 2000, over 10,000 Caspian seals are estimated to have died along the coast of Kazakhstan, with high death rates also reported from the coasts of Azerbaijan and Turkmenistan. Necropsies demonstrated that canine distemper virus was also the primary cause of death for all of the dead Caspian seals.

Despite its early discovery, the Baikal seal remained all but unknown to western scientists until the 20^th century, and only in 1909 did specimens first arrive in Britain. These were collected by Charles Hose who was using the Trans-Siberian railway to get to Sarawak (which is where, in 1895, he discovered the cetacean that later became known as Fraser’s dolphin Lagenodelphis hosei). During a two-day stop at Lake Baikal, Hose managed to get local fishermen to catch three of the seals for him, alive, and he then resumed the train journey with the seals stuck in the luggage racks of his train compartment. Two of the seals died and Hose performed dissections on them while still in the carriage, ‘flinging the more perishable parts out of the train window, to the consternation of fellow passengers’ (King 1983, p. 92). The third seal died while on a ship bound for Shanghai. This little-known information was published in Hose’s autobiographical work of 1927, amusingly titled Fifty Years of Romance and Research or a Jungle-Wallah at Large. I’ve never seen this book, but the information is repeated in Judith King’s excellent Seals of the World. The first live Baikal seals weren’t seen in Britain until 1959 when Moscow Zoo sent a pair to London Zoo.

Baikal seals are morphologically interesting for a number of reasons. Firstly, they are one of the smallest seals, reaching just 1.4 m and 80-90 kg at most (Ringed seals are smaller, as are members of some lake-dwelling Common seal populations). Secondly, for their size they have among the biggest eyes of any pinniped, with the eyeballs being so big that they almost contact one another along the skull midline. Thirdly, the huge eyes appear to have forced other skull structures to become compressed or reduced: the frontal sinuses are strongly compressed and located further ventrally than is normal for seals; the nasal cavity has been forced into an unusually low position; and the brain has been displaced backwards. The jaw muscles, the ear region and the bones around the jaw joint are also modified relative to the condition in other seals, mostly in being smaller and weaker (Endo et al. 1998a, b, 1999). The foreflippers and their claws are larger and stronger in Baikal seals than is usual for seals, and the foreclaws are distinctive in being triangular in cross-section and in having a marked dorsal ridge at their distal end. It is inferred that these forelimb structures make Baikal seals better at making and maintaining breathing holes and grasping prey than other seals (Thomas et al. 1982).

Baikal seals are thermophobic and pagophilic (that is, they avoid heat and like ice and snow), and their pups have white silky natal fur and are born on the ice that covers the lake between February and April. In these respects, Baikal seals are like the cold-adapted Ringed seal, Harp seal P. groenlandica and Ribbon seal P. fasciata, and as we’ll see this has implications for Baikal seal origins and history. Despite their small size, they are surprisingly long-lived, with males living to 52 and females to 56 (incidentally, Caspian seals are also long-lived, surviving to age 50). Average longevity for seals is about 20 years. Further remarkable is that female Baikal seals continue to reproduce while in their fourth decade.

The great mystery, of course, concerns how the seals got into Lake Baikal: ultimately, we don’t yet know the proper answer, but that hasn’t stopped people from speculating. In fact it’s been said that more articles have been published on the biogeography of Lake Baikal’s seals than on the biogeography of all other pinnipeds combined. Even without the seals, Lake Baikal is a pretty remarkable lake, and would be better termed an inland sea. It’s 636 km long, nearly 80 km wide at its widest point, its average depth is 700 m and its maximum depth is 1.6 km. It is home to assorted endemic molluscs, crustaceans and nearly 60 fish species, and at least some of these animals are clearly of Arctic origin.

To date, two competing hypotheses have been proposed to explain the origins of the Baikal seals. Hypothesis 1 will be termed here the ‘Paratethyan hypothesis’, while hypothesis 2 will be termed the ‘Arctic origins hypothesis’.

The Paratethyan hypothesis

The Paratethyan hypothesis accepts the conclusion, supported by some details of morphology, that Baikal seals, Ringed seals and Caspian seals all form a clade (the genus or subgenus Pusa*). Diverse phocine seals – some apparently resembling the extant Pusa** seals – are known to have inhabited Paratethys during the Miocene (Paratethys was a brackish inland sea that covered much of south-east Europe and south-west Asia during the Miocene) and, according to the Paratethyan hypothesis, it is phocines from this region that managed to invade the Caspian Sea, later getting as far east as Lake Baikal. During the Pliocene, Paratethys was linked to the Arctic Ocean via a seaway just west of the Urals, apparently, and accordingly it has been proposed that the Ringed seal of the Arctic Ocean descends from a phocine that migrated north from the Paratethys (Ray 1976, Grigorescu 1977) [adjacent image shows a Ringed seal].

* Whether the Pusa seals really share a single ancestor, however, has been contested and a recent DNA study found no support for the monophyly of Pusa: instead, the Baikal seal formed a clade, albeit weakly supported, with the Grey seal Halichoerus grypus (Palo & Väinölä 2006).

** Pusa pontica, from the Upper Miocene of Ukraine, has been referred to Pusa, but this is probably not correct.

Needless to say, there are problems with this hypothesis. Firstly, while it appears that the Caspian Sea is a relict of Paratethys (as is the Aral Sea), Lake Baikal appears way too far in the north-east for this to work, and where are all the connecting rivers and lakes that would be required in order to get seals from Paratethys all the way over to the Siberian interior? There are big lakes found between the Aral Sea and Lake Baikal, such as Lake Balkash, but they aren’t connected to the Paratethyan remnants, nor were they in the past. Secondly, the Paratethyan hypothesis requires that the phocines ancestral to Baikal seals and Ringed seals were animals of enclosed basins, relatively low latitudes and warm temperatures, and this is problematic given that Baikal and Ringed seals are thermophobic and pagophilic, with thickly-furred pups kept in snow dens. Furthermore, excepting the unusual inland populations, all phocines are oceanic, and not denizens of enclosed basins.

The Arctic origins hypothesis

The competing hypothesis posits that neither Baikal seals nor Ringed seals have descended from Paratethyan phocines that migrated south to north, but that all the pagopholic Pusa seals are of Arctic ancestry, and that seals got into Lake Baikal from the north. The fact that Baikal seals are thermophobic and pagopholic provides support for this model, as does the fact that many Baikal animals are apparently Arctic in origin.

Further support for the Arctic origins hypothesis comes from the fact that large ice-dammed lakes occupied central Siberia about 300,000 years ago. These apparently had connections with the Arctic Ocean and, via the Enisei-Angara river system, with Lake Baikal. Temporary downstream connections with the Caspian Sea also existed. This hypothesis better explains the ecology and life history of Baikal (and Caspian) seals, and is also superior to the Paratethyan hypothesis in that there are (and were) plausible dispersal routes that allowed the seals to get into the inland lakes. Worth noting is that Baikal seals occur in the rivers that flow north out of Lake Baikal even today. Particularly notable is a case where a seal was observed at the Irkutsk Dam on the Angara River, 400 km away from the lake (Thomas et al. 1982).

All in all, the Arctic origins hypothesis better fits the data and is the favoured hypothesis of recent authors (Deméré et al. 2003, Palo & Väinölä 2006). However, this isn’t the end of the debate. The degree of genetic divergence found amongst living phocines suggests – based on molecular clock inferences (which are always controversial and problematic) – that Baikal seals and other phocines diverged around 4 million years ago, during the late Pliocene. Why is this interesting? Because a divergence that occurred at this time doesn’t match with either the Paratethyan or the Arctic origin hypothesis.

According to the former model, the ancestors of Baikal seals must have diverged from other phocines some time during the Miocene, and according to the latter model, Baikal seals evolved from a more northerly ancestor during the Pleistocene. In other words, if the genetic data is accurate, then the evolution of Baikal seals pre-dates the key event that is supposed to explain their distribution: the development of immense Siberian lakes connected both to the Arctic Ocean and to Lake Baikal. Palo & Väinölä (2006) therefore concluded that ‘the actual geographical conditions that would have facilitated the continental invasions in these times still remain undocumented and enigmatic’ (p. 70).

Huh. And there the story ends. For a previous seal-themed post see Swan-necked seals.

Coming soon: obscure dinosaurs of the Kimmeridge Clay. For the latest news on Tetrapod Zoology do go here.

Refs - -

Bonner, N. 1994. Seals and Sea Lions of the World. Blandford, London.

Deméré, T. A., Berta, A. & Adam, P. J. 2003. Pinnipedimorph evolutionary biogeography. Bulletin of the American Museum of Natural History 279, 32-76.

Endo, H., Sasaki, H., Hayashi, Y., Petrov, E. A., Amano, M. & Miyazaki, N. 1998a. Functional relationship between muscles of mastication and the skull with enlarged orbit in the Baikal seal (Phoca sibirica). Journal of Veterinary Medical Sciences 60, 699-704.

- ., Sasaki, H., Hayashi, Y., Petrov, E. A., Amano, M. & Miyazaki, N. 1998b. Macroscopic observations of the facial muscles in the Baikal seal (Phoca sibirica). Marine Mammal Science 14, 778-788.

- ., Sasaki, H., Hayashi, Y., Petrov, E. A., Amano, M., Suzuki, N. & Miyazaki, N. 1999. CT examination of the head of the Baikal seal (Phoca sibirica). Journal of Anatomy 194, 119-126.

Grigorescu, D. 1977. Paratethyan seals. Systematic Zoology 25, 407-419.

Kennedy, S., Kuiken, T., Jepson, P. D., Deaville, R., Forsyth, M., Barrett, T., van de Bildt, M. W. G., Osterhaus, A. D. M. E., Eybatov, T., Duck, C., Kydyrmanov, A., Mitrofanov, I. & Wilson, S. 2000. Mass die-off of Caspian seals caused by canine distempter virus. Emerging Infectious Diseases 6, 637-639.

King, J. E. 1983. Seals of the World. British Museum (Natural History), London.

Palo, J. U. & Väinölä, R. 2006. The enigma of the landlocked Baikal and Caspian seals addressed through phylogeny of phocine mitochondrial sequences. Biological Journal of the Linnean Society 88, 61-72.

Ray, C. E. 1976. Geography of phocid evolution. Systematic Zoology 25, 391-406

Smith, R. J., Hobson, K. A., Koopman, H. N. & Lavigen, D. M. 1996. Distinguishing between populations of fresh- and salt-water harbour seals (Phoca vitulina) using stable-isotope ratios and fatty acid profiles. Canadian Journal of Fisheries and Aquatic Science 53, 272-279.

Thomas, J., Pastukhov, V. & Petrov, E. 1982. Phoca sibirica. Mammalian Species 188, 1-6.

History writ large at Electric Politics

2006-12-10T12:23:00.000Z

As mentioned in the agama post, I recently did a podcast interview, and it’s now available online. Strangely perhaps, it wasn’t done for a website that specialises in zoology, nor even in science, but for George Kenney’s excellent Electric Politics site. Covering all manner of issues related to the world of American and/or global politics, Electric Politics might seem an odd venue for a podcast interview with a palaeontologist, but perhaps this is an indication of – dare I say it – how popular Tetrapod Zoology has become. Jon Downes insists on calling me the ‘people’s palaeontologist’*, and presumably that’s a reference to the same thing [the adjacent image shows me, after a heavy rain-storm, at a dig site. I don’t normally dress like that, honest].

* Inspired itself by a soundbite once used by Tony Blair.

As is the case with a lot of people, I’m never really happy when I listen back on myself talking in interviews – I always wish that I’d said things differently, or explained them better – but overall it’s pretty good and George was great fun to talk to. We spoke about the evolution of domestic dogs, about brain size and intelligence, about speculations on smart dinosaurs and the future evolution of humans, and also on cryptozoology, sasquatch and dinosaur extinction. There are a few parts of the interview where I become confused and lose my train of thought, and there’s a hilarious segment where I totally lose the plot in trying to explain the history of domestic horses. Cringe.

For the record, the deal with horses in North America is that, while members of the genus Equus were numerous and important there in the Pleistocene, they later became extinct (to quote R. Dale Guthrie (2003): ‘equid species dominated North American late Pleistocene faunas in terms of abundance, geographical distribution, and species variety, yet none survived into the Holocene epoch’ (p. 169)). Meanwhile, Asian steppe horses were domesticated about 6000 years ago (probably in or around Ukraine and Kazakhstan [nod to Steve Bodio]), apparently from several different groups of wild horses (Bennett & Hoffmann 1999, Pennisi 2001, Vilà et al. 2001), and not until the 16^th century did Spanish conquistadors reintroduce horses to the Americas. The descendants of these animals, the feral American horses known as mustangs, were being killed for pet food as recently as the 1960s and, despite the 1971 Free Roaming Wild Horse and Burro Act, remain persecuted today. About 42,000 currently live wild in North America. The fact that the wild horses closest to the ancestry of domestic horses, such as the tarpan E. ferus and takhi E. przewalskii, are extinct or highly endangered is an interesting point and probably not a coincidence [the horses in the adjacent image are New Forest ponies].

Anyway, you can listen to and/or download the interview – History writ large – here. It’s a long interview, at 85 minutes or so. Many thanks to George for the invitation, and for the opportunity to do this.

On another subject, thanks to those who have made recent donations to the blog: it’s really appreciated, and helps immensely. I’ve been trying to figure out a way to get enough funding to become a full-time blog writer, but sadly I don’t think that’s an option.

Coming soon: that inconvenient seal, obscure dinosaurs of the Kimmeridge Clay, more on pterosaurs, temnospondyls, and more cryptic intermediates in agamas. For the latest news on Tetrapod Zoology do go here.

Refs - -

Bennett, D. & Hoffmann, R. S. 1999. Equus caballus. Mammalian Species 628, 1-14.

Guthrie, R. D. 2003. Rapid body size decline in Alaskan Pleistocene horses before extinction. Nature 426, 169-171.

Pennisi, E. 2001. Horses domesticated multiple times. Science 291, 412.

Vilà, C., Leonard, J. A., Götherstrom, A., Marklud, S., Sandberg, K., Lidén, K., Wayne, R. K. & Ellegren, H. 2001. Widespread origins of domestic horse linages. Science 291, 474-477.

Harduns and toad-heads; a tale of arenicoly and over-looked convergence

2006-12-02T13:44:00.001Z

So, life goes on. Overall, I feel that the sasquatch post – the most popular article yet posted to this blog (attracting c. 3000 hits on one day) – got a fair hearing, though I continue to be unhappy with people who consider themselves sceptics but are, in fact, ‘rejectionists’ (and I’m not necessarily referring to anyone who posted comments to this blog). While research plans have generally fallen by the wayside due to other commitments, various projects involving pterosaurs, sauropods and other Cretaceous tetrapods are still on-going. Mark Witton (yes yes, Buckingham Palace, blah blah blah) and I are now collaborating on a project about azhdarchid ecology, and the big British dinosaurs manuscript is STILL trundling through the system (ah, the wonder that is co-authors). The other day I attended the Hampshire Wildlife Trust bat and badger social evening and got to listen to recordings of screaming rabbits, all in the name of an evening’s entertainment. Then there was the podcast interview: more on that in a few days [adjacent image of Laudakia - see below - from http://www.herpetofauna.at/].

And given that I’ve hardly mentioned it so far, feel free to nip over to Biology & Palaeontology Qs & As: a blog site where people can ask a team of experts any question about, well, biology or palaeontology. The august team of experts include P. Z. Myers, Steve Jones, Carl Zimmer and a host of others. It’s run by my good friend Dave Hone: sorry for not mentioning it before Dave.

Moving on… today I am covering one of the subjects that I’ve been planning to cover for months and months and months: agamas, or agamids (previously promised in At last, Dr Naish, ‘Angloposeidon’, the unreported story, part I, Did ichthyosaurs fly? and Macropredation in lions). As usual, I’ve had to restrict my coverage to one specific area of the agamid world, and I hope to write more about this fascinating group in future.

Agamids are iguanian lizards found across Africa, southern Asia and Australasia, and they’re fascinating for a host of reasons. For one they include some of the most fantastically ornamented of all lizards, with numerous species sporting sail-like frills, spiky crests, horns, knobs and other structures. They are often territorial and sexually dimorphic; they include the gliding Draco species, the herbivorous mastigures (Uromastyx), and the often bizarre Australasian dragons. Adjacent image shows the nifty threat display used by some toad-headed agamas, on which there is more below...

Studies generally agree that there are three major agamid clades: the Australo-papuan clade (Amphibolurinae), the southern Asian clade (Draconinae), and the African-west Asian clade (Agaminae). Several agamids, including butterfly agamas, mastigures and water dragons, don’t fit into these groups and sit on their own. The antiquity of the divergences within Agamidae has proved controversial, with some authors arguing that the major clades diverged as a consequence of Gondwanan vicariance (Macey et al. 2000). If this is true then these groups are more than 100 million years old, but this is highly unlikely and probably wrong (Hugall & Lee 2004). Agamids are close relatives of the bizarrely specialised chameleons: more on that later. Agamids and chameleons share what are known as acrodont teeth: a morphology in which the teeth are fused to the jaw bones, and are therefore not replaced during the animal’s life (however, socketed teeth – which are replaced continuously – are usually found at the front of an agama’s jaws).

The herpetofauna’s lament

There are over 400 living agamid species, and this brings me on to pet peeve # 407. Should you wish to learn about – say – all the species of any given group of birds, you have it easy. Entire volumes devoted to bird families exist, and detailed species-by-species accounts of all extant bird species can be found in the outstanding, multi-volume Handbook to the Birds of the World, produced by Lynx Edicions. For mammals you have the awesome two-volume Walker’s Mammals of the World as your first stop, as well as McDonald’s Encyclopedia of Mammals. Lynx Edicions are also working on a species-by-species, multi-volume set that goes through all the world’s extant mammals.

But what really bugs me is that there are no such sources for living reptile or amphibian species. Well, there are for crocodilians and testudines, and also for a few charismatic groups such as chameleons and monitor lizards. But it is otherwise pretty much impossible to get hold of species-level reviews of amphibian and reptile species. Why is this? It drives me nuts. The only way to even come close to getting some understanding of species-level diversity within non-avian, non-mammalian tetrapods seems to be to obtain ALL of the primary literature, and/or to visit the collections of ALL relevant repositories. Both aims are of course impossible.

I rely on field guides a lot, but because they are heavily biased in terms of area coverage (e.g., there are tens of field guides on the reptiles of southern Africa, but hardly any on much of western Africa) there are still whole suites of species that, at best, only ever get listed or mentioned, let alone illustrated or described. So even today, people interested in herpetology are afflicted with the most basic of problems: a lack of the right kind of literature. Having mentioned lizards and books, I am forced to make an honorary mention of Pianka & Vitt’s Lizards: Windows to the Evolution of Diversity. Awesome, and one of my favourite books on any subject.

Moody’s splintering of Agama

Here in Europe – or, as I like to call it, the European Field Guide Region (EFGR) – there is usually stated to be just one agamid, the Hardun, Starred agama or Sling-tailed agama Laudakia stellio [image at left: from sundancecamp.com]. This isn’t correct, however, as we have three species of toad-headed agamas (Phrynocephalus) in the EFGR, as well as two additional Laudakia species. All of these lizards belong to the agamid clade Agaminae, and it’s a few members of this group that I’m going to look at here.

The Sling-tailed agama is a large, robust lizard (c. 300 mm long) with an armour-plated look, and it’s wide ranging, occurring across eastern Europe, northern Africa, north-east Arabia and Asia. It can change colour, from light brown to almost black, and is an excellent climber on both trees and rocky surfaces. Multiple (20) species of Laudakia have been named, but it is has proved almost impossible to reliably differentiate many of them on the basis of either morphology or range.

Those field guides that I mentioned always use the name Agama stellio for L. stellio. This is because, while the name Laudakia isn’t new (having been coined by Gray in 1845), it later became sunk into synonymy with Agama and only became resurrected following S. Moody’s 1980 doctoral study on agamid relationships. This is one of those annoying studies that gets cited all the time, but has yet to be published. Moody argued that the genus Agama was, as perceived for most of the 20^th century, actually a polyphyletic assemblage of quite distinct, disparate agamines which deserved separation as Agama Daudin, 1802 sensu stricto, Xenagama Boulenger, 1895, Pseudotrapelus Fitzinger, 1843, Trapelus Cuvier, 1817 and Stellio Laurenti, 1768. Moody’s concept of Stellio proved to be an artificial assemblage of distinct Eurasian and African species, and in any case this generic name isn’t available for agamines (it was first used for a monitor lizard). So the Eurasian forms were then labelled with Gray’s Laudakia, while Fitzinger’s name of 1843, Acanthocercus, became attached to the African forms. There is also the confusing suggestion that Placoderma Blyth, 1854 should be used for some members of Laudakia (Henle 1995): confusing because placoderms are a group of ancient fossil fishes.

Basing their phylogeny on that of various previous studies, Stuart-Fox & Owens (2003) depicted Laudakia as the sister-taxon to a Phrynocephalus-Bufoniceps clade (the latter are the toad-headed agamines, more below: adjacent image shows P. melanurus, image from the Siberian Zoological Museum site). Macey et al. (2006) found Laudakia to be paraphyletic as toad-heads were nested within it. And of the Laudakia species, L. stellio was the one closest to the toad-heads. Right now, the monophyly of Laukadia remains controversial, and the idea that L. stellio might be particularly close to toad-heads is particularly interesting. I would dearly love to know if it exhibits any morphological characters that make it closer to toad-heads than to other members of Laudakia. In other words, is it a sort of cryptic intermediate?

Toad-heads old and new

Toad-headed agamas, or toad-heads (Phrynocephalus Kaup, 1825), are a mostly desert-dwelling Asian group of agamines, occurring as far east as Mongolia, as far south as southern Arabia and Pakistan, and as far west as Turkey. The adjacent image (from reptiles.passion) answers the question: why are they called toad-heads? There are more than 40 species, but species boundaries and often unsure and several taxa have been only briefly characterised. An important component of Asian desert fauna, some toad-head species occur below sea level while others inhabit high plateaus, and many are specialised for highly arid, cold environments. As is seen in other squamate groups that have invaded cool, elevated places, toad-heads have evolved viviparity: this is present in just six Chinese species.

The Rajasthan toad-head Bufoniceps laungwalaensis, originally described in 1978 as a new species of Phrynocephalus, was awarded its own genus by Arnold (1992) [adjacent image from here]. Unlike the Phrynocephalus species, Bufoniceps has a short tail that is not held raised or curled and it still possesses an external ear opening (abeit a very small one). It’s small, with a total length of only c. 100 mm (snout to vent length is c. 60 mm). A diurnal, fast-moving denizen of sand dunes, it feeds on ants, beetles and other insects, and buries itself in soft sand when not active or when pursued. This doesn’t work against humans as an obvious trace in the sand is made. Bufoniceps and Phrynocephalus share a large number of characters, including a notably short snout, a strongly reduced ear opening, a short retroarticular process (= a muscle attachment site projecting from the rear edge of the lower jaw), and fringes of pointed scales on their digits. However, Bufoniceps lacks a suite of derived characters present in Phrynocephalus, and as such has been regarded as a primitive sister-taxon to the latter (Arnold 1992, 1999a, b).

In contrast to Laudakia, most Trapelus species, and various other agamines, toad-heads are strictly terrestrial and do not climb. But because there are toad-heads that live both on soft, wind-blown sand, and on stony or gravely ground, herpetologists have disagreed as to which habitat is the ancestral one for the group. If Bufoniceps is the sister-taxon to Phrynocephalus, then its sand-dune habitat suggests that arenicoly (= ‘sand loving’) is primitive for toad-heads, and that saxicoly (= ‘stone loving’) evolved later on. This is further supported by the fact that fringed toes evolved early in the group, as did a countersunk lower jaw, valvular nostrils, fringes of elongate scales along the eyelids, and a reduced external ear (Arnold 1999a). All of these features are associated with an entry into sandy habitats, as they help protect the animal from sand grains.

As with so many phylogenetic hypotheses that seem reasonable based on morphological data, the idea that Bufoniceps really is a sort of proto-Phrynocephalus has recently been challenged on the basis of genetic information, however. By sampling mitochondrial data from Xenagama [pictured at left: image from gherp.com], Bufoniceps and other agamines, Macey et al. (2006) found Bufoniceps to be the sister-taxon to Trapelus, and a close relationship with Phrynocephalus was rejected. If this is correct then the characters shared by Phrynocephalus and Bufoniceps are convergences to arenicoly, and pretty remarkable convergences at that.

Agamines are a really interesting group in terms of adaptation: we have scansorial, arenicolous and saxicolous species, the evolution of viviparity, and morphological transitions such as external ear loss. However, if the new genetic studies cited here are correct, then they are even more interesting in demonstrating an outstanding and previously overlooked example of convergent evolution, and in perhaps exhibiting a few ‘cryptic intermediates’. And there’s more to say on the latter: watch this space. For the latest news on Tetrapod Zoology do go here.

Refs - -

Arnold, E. N. 1992. The Rajasthan toad-headed lizard, Phrynocephalus laungwalaensis (Reptilia: Agamidae), represents a new genus. Journal of Herpetology 26, 467-472.

- . 1999a. Phylogenetic relationships of Toad-headed lizards (Phrynocephalus, Agamidae) based on morphology. Bulletin of British Museum of Natural History (Zoology) 65, 1-13.

- . 1999b. Modes of ear reduction in iguanian lizards (Reptilia, Iguania); different paths to similar ends. Bulletin of British Museum of Natural History (Zoology) 65, 165-171.

Henle, K. 1995. A brief review of the origin and use of ‘Stellio’ in herpetology and a comment on the nomenclature and taxonomy of agamids of the genus Agama (sensu lato). Herpetozoa 8, 3-9.

Hugall, A. F. & Lee, M. S. Y. 2004. Molecular claims of Gondwanan age for Australian agamid lizards are untenable. Molecular Biology and Evolution 21, 2102-2110.

Macey, J. R., Schulte, J. A., Fong, J. J., Das, I. & Papenfuss, T. J. 2006. The complete mitochondrial genome of an agamid lizard from the Afro-Asian subfamily agaminae [sic] and the phylogenetic position of Bufoniceps and Xenagama. Molecular Phylogenetics and Evolution 39, 881-886.

- ., Schulte, J. A., Larson, A., Ananjeva, N. B., Wang, Y., Pethiyagoda, R., Rastegar-Pouyani, N. & Papenfuss, T. J. 2000. Evaluating trans-Tethys migration: an example using acrodont lizard phylogenetics. Systematic Biology 49, 233-256.

Stuart-Fox, D. & Owens, I. P. F. 2003. Species richness in agamid lizards: chance, body size, sexual selection or ecology? Journal of Evolutionary Biology 16, 659-669.

Frame 352, and all that

2006-11-29T00:46:00.000Z

For some time now I’ve been toying with the idea of writing a blog post about sasquatch, North America’s legendary cryptic ape. And, generally, I’ve decided that doing so would be a really bad idea: I am chicken, and as someone trying to gain a reputation within the academic world, I think that even expressing an interest in issues like this is a bad idea. That’s ridiculously unfair of course, stemming only from ill-informed knee-jerk negativity to this subject, and given that scientific inquiry of any phenomenon is a worthwhile pursuit, I like to think that more zoologists should actually get informed about mystery animals (for a previous post making the same argument go here). I note that hardly any hard-line sceptics of things such as sasquatch display familiarity with the literature on the subject [adjacent image shows frame 310 of the Patterson film: see below].

In the interests of hypothesis testing, I finally decided: what the hell. My hypothesis is: will writing about sasquatch negatively affect my career prospects? Well, let’s test the hypothesis. Let me state from the start that I do not “believe” in sasquatch, nor am I planning to promote either an anti-sasquatch, or a pro-sasquatch, point of view. What I have learnt from research on this area is that – contrary to the assertions of some – the evidence for sasquatch is, at the very least, scientifically interesting and worthy of investigation.

While purported evidence for the supposed reality of sasquatch continues to attract strong criticism, more interesting in my view is that a number of academically qualified primatologists have recently gone on record in stating that the evidence for sasquatch is scientifically compelling. These people do not only include well-known sasquatch proponents, such as the late Grover Krantz (1931-2002) of Washington State University, or Jeff Meldrum of Idaho State University. Daris Swindler (professor emeritus of physical anthropology at the University of Washington, author of Atlas of Primate Anatomy) stated, after examining the Skookum body cast (a large impression, made in mud, from Washington state, apparently created by a reclining man-like primate), that the heel impression visible on the cast is definitely that of a giant unknown primate. J. H. Chilcutt, an expert on human and non-human primate fingerprints (who initially examined casts of sasquatch tracks because he felt confident that he could debunk them), has expressed his absolute confidence in the validity of dermal ridges on footprints as demonstrative of the reality of sasquatch. On the Whitewolf Entertainment TV documentary ‘Sasquatch: Legend Meets Science’ (2003) he stated “I stake my career on it”.

Here I am going to discuss one particular piece of evidence for sasquatch: the Patterson-Gimlin film. This is that famous short piece of film that you’ve probably seen on TV many times: it depicts what appears to be an obviously female sasquatch striding across a clearing from left to right [for M. K. Davis’ stabilised version of the film go here]. You’ve probably heard that the film has been revealed to be a hoax. Well, sorry, that ain’t true.

On October 20^th 1967, Roger Patterson and Robert Gimlin claimed to capture on film an unexpected encounter with an adult female sasquatch. The resulting footage, filmed at Bluff Creek, northern California, contains 952 frames, but uncertainty over the filming speed affects the real-time duration of the event. Patterson’s camera was either set at 16 or 24 frames per second (fps), with 16 fps now considered more likely. It is not true that the footage is grainy or blurry, and high-resolution enlargements such as those produced by M. K. Davis (here shown standing next to the best of the enlargements) reveal a surprising amount of detail. Literally whole books have been written about the footage (e.g. Bayanov 1997), so I will try and keep these comments brief. In order to be impartial, I will refer to the alleged sasquatch as TAS (= The Alleged Sasquatch).

1. TAS looks genuine. Its coat is glossy, conforms to the underlying contours, muscular bulges, joints and other structures in the body, and looks realistic compared to living mammals. What appears to be a shallow parting extends axially along the spine and between the buttocks [in adjacent image, note the demarcated buttocks and apparent wear on the buttocks]. As TAS moves, its muscles (in its legs and elsewhere) can be seen to bulge and flex beneath the fur as they do in living mammals. TAS’s gait is fluid and natural and it differs in subtle details of posture and proportion from humans (see points 2 and 3). Its toes are seen to lift at one point. Its large breasts bounce and sway in a manner which looks realistic compared to how unsupported human breasts move during locomotion. It is also intriguing that TAS’s compliant gait and protruding heel match features reported by eyewitnesses (see point 2). High quality enlargements have been published of key frames from the footage several times (e.g. Bayanov 1997, Murphy et al. 2004) so it is easy to check all of these assertions. Put in its simplest terms: despite claims to the contrary, TAS looks realistic.

2. TAS walks with a compliant gait, and not with the same striding knee-locking gait of humans [adjacent image shows frame 352, the most famous and oft-shown part of the film]. Its knee is never fully straightened in its step cycle, even in the supporting phase. Its arms swing slightly more than those of humans, and its hands and wrists are held supinated and slightly flexed with the fingers curved (this is unlike the normal hand posture of humans). It’s clearly possible that all of these features could be faked by a knowledgeable human, and Daegling & Schmitt (1999) argued that the gait and speed used by TAS can be reproduced by humans. That person would, however, have to not only conform physically to the dimensions of TAS (see point 3), but would also have to be very good at walking with an unusual gait which is practised so well that it has convinced experts in biomechanics and primate anatomy (see point 4). That person would also have to be an expert, or at least supervised by one, on the eyewitness data (which describes identical points of posture and morphology). It is unlikely that such a person exists and/or was available to Patterson and/or Gimlin in 1967, and extensive biographical research on Patterson and Gimlin and their friends and colleagues has failed to uncover the existence of any such person.

3. TAS is physically large and with proportions that appear to be unlike those of our species. Its intermembral index (the ratio of humerus + radius length to femur + tibia length) is between 80 and 90, whereas in our species it averages 72*, and its breadth across its shoulders is about 35% of its total height. Krantz (1999) asserted that some humans (including inuit people) have a shoulder breadth that exceeds 30% of total height (this is apparently not the case in people that exceed 2 m in height), and that other data also indicates that the creature exceeds in torso width any human. Krantz (1999) concluded on the basis of this evidence ‘I can confidently state that no man of that stature is built that broadly’. However, Daegling & Schmitt (1999) challenged this torso-breadth data, and argued that the estimates do overlap with that from tall humans.

* In chimps and gorillas the intermembral indices are 106 and 117, respectively. TAS therefore seems intermediate between chimps and humans with regard to this feature.

Patterson and Gimlin photographed, and took casts from, a trackway which (they asserted) was made by TAS. These photographs and tracks survive today and both (i) appear genuine* and (ii) correspond with the details of TAS’s size and gait as seen in the footage. Average track length was 36.8 cm, and because the full length of TAS’s foot sole can be seen in several frames, the sole : total height ratio of about 1 : 5 gives a rough height of 184 cm. A similar height has been estimated by triangulation, by working out how the stride length used by TAS matches with humans of various statures, and by other methods.

* That is, like other ‘good’ sasquatch prints, they appear to have been made by a large, very heavy hominid with a flexible foot that exhibits several consistent anatomical novelties.

4. Several workers experienced with primate biomechanics and locomotion have examined the footage, and in several cases have published comments on it. All have concluded either that the film is genuine and depicts a non-human primate, or have admitted that their examination was inconclusive.

Dmitri Donskoy [Chief of the Chair of Biomechanics at the USSR Central Institute of Physical Culture, Moscow] concluded ‘[my analysis reveals] the walk of the creature as a natural movement without any signs of artfulness which would appear in intentional imitation. At the same time, with all the diversity of human gaits, such a walk as demonstrated by the creature in the film is absolutely nontypical of man’.

D. W. Grieve [Reader in Biomechanics, Royal Free Hospital School of Medicine, London] concluded ‘The possibility of fakery is ruled out if the speed of the film was 16 or 18 fps [as mentioned above, it was apparently filmed at 16 fps]. In these conditions a normal human being could not duplicate the observed pattern, which would suggest that the sasquatch must possess a very different locomotor system to that of man’.

Grover Krantz, well known as an advocate of sasquatch but nonetheless still an experienced and qualified anthropologist, argued that the creature’s size, proportions and gait demonstrated its genuine nature, concluding ‘there is no possibility that the film can be a man in a fur suit’. Bayanov (1997) cited views from several Russian biomechanists who thought that the creature’s gait could not be reproduced by a human. Jürgen Konczak [associate professor in the School of Kinesiology and director of the Human Sensorimotor Control Laboraties at Minnesota University] concluded that the creature’s gait indicated that it was genuine and non-human. Other ‘positive’ interpretations of the footage, voiced by experienced, qualified biomechanists and/or primatologists, were broadcast in the Whitewolf Entertainment TV documentary ‘Sasquatch: Legend Meets Science’ (2003).

In view of this large number of ‘positive’ interpretations, most of which come from authoritative, technically qualified experts who do not have any axe to grind on the issue of sasquatch, what evidence has been marshalled by those who assert that the film is faked? To date, none. No analysis has been performed which shows that the creature can be explained as a man in a suit. Published objections have either asserted that the animal walks in a manner ‘consistent in general terms with the bipedal striding gait of modern man’ (Napier 1974), or have pointed to the presence of furry breasts, the presence of a sagittal cranial crest in a female, or the presence of breasts in a creature without female-like hips and a waist, as problems showing that the film must have been faked. These objections are all clearly erroneous (e.g. it is difficult to be confident that furry breasts are somehow impossible – while many primates do sport naked pectoral skin around their nipples and areolae, human breasts are hairy, it’s just that the hairs are very small and thin; sagittal crests are size-related, and only absent in the females of most hominid species because females do not match adult males in the size of their cranial musculature; broad hips and a waist are characters of our species, and not of other hominids or primates [gorilla skeleton at left]). Napier’s objections were vague and have not been supported by other workers experienced in biomechanics.

David Daegling [associate professor of anthropology at Yale University] and Daniel Schmitt [assistant professor in the Department of Anthropology, Duke University Medical Center] published an article in Skeptical Inquirer in which they argued that TAS’s size and style of gait can be reproduced by people. They were still unable to assert that it was fake however, concluding ‘Based on our analysis of gait and problems inherent in estimating subject dimensions, it is our opinion that it is not possible to evaluate the identity of the film subject with any confidence’.

Multiple claims have been made that the footage was faked by a known individual, and that this individual has provided a death-bed confession, or something like that. It has been easy to knock down all of these claims and show them to be fabrications (e.g. Coleman 2003, Murphy et al. 2004, Vella 2004, Perez 2005).

5. In view of these observations, it is difficult to take seriously claims that TAS is actually some tall guy in a gorilla costume. Even today there is no maker of fake/synthetic fur, or of animal costumes, who can reproduce something this realistic, nor are there any suits which look so realistic, which allow the mimicry of moving musculature and breasts, and which are anatomically accurate compared to living primates. Two serious attempts have been made to reproduce the film using a man in a specially designed suit: one for the BBC TV series ‘The X Creatures’ [image at left]; the second for Kal Korff’s documentary ‘The Making of Bigfoot’. In both instances the resulting attempt to discredit the Patterson-Gimlin film backfired: their results look like a man in a monkey suit, and in no way come even close to resembling TAS in the 1967 Patterson-Gimlin film. Several special effects experts have been consulted on how possible it might be to reproduce what’s seen in the footage (this is particularly relevant as there have been repeated claims that someone in the Hollywood special effects community manufactured a suit for Patterson), including John Chambers [designer of the ape costumes seen in ‘Planet of the Apes’]. While some have claimed that the construction of a suit matching what’s seen in the Patterson film would be easy or possible, I am troubled by the fact that no-one has yet replicated it. At least some special effects people have stated that the creature seen in the footage exceeds in accuracy and realism the special effects available to workshops today, let alone those existing in 1967.

There’s a lot more that could be said on this subject, but I’ll leave it at that. I have not discussed Roger Patterson’s personal circumstances (relevant to claims that he faked the footage for money or fame), nor have I touched on the interesting story of what a farce Patterson and Gimlin’s eventual development and treatment of the film was. As Richard Greenwell (1942-2005) – former secretary of the International Society of Cryptozoology – said to me in a letter of March 2000: ‘In the big picture it matters little if Bigfoot exists or not; what matters is that proper procedure be followed in examining such evidence – or any evidence’.

UPDATE (29-11-2006): Loren Coleman has written a blog post about this one - see Napier, Naish, and Frame 352. For the latest news on Tetrapod Zoology please go here.

Refs - -

Bayanov, D. 1997. America’s Bigfoot: Fact, Not Fiction. Crypto Logos, Moscow.

Daegling, D. J. & Schmitt, D. O. 1999. Bigfoot’s screen test. Skeptical Inquirer May/June 1999, 20-25.

Coleman, L. 2003. Bigfoot! The True Story of Apes in America. Paraview Pocket Books, New York.

Krantz, G. S. 1999. Bigfoot Sasquatch Evidence. Hancock House, Surrey, B.C. & Blaine, WA.

Murphy, C. L., Green, J. & Steenburg, T. 2004. Meet the Sasquatch. Hancock House, Surrey, B.C. & Blaine, WA.

Napier, J. 1974. Bigfoot. Readers Union, Newton Abbot.

Perez, D. 2004. In defence of the Patterson-Gimlin film. Fortean Times 192, 36-37.

Vella, P. 2004. J’accuse. Animals & Men 34, 42-48.

The Madagascar pochard returns

2006-11-22T13:29:00.000Z

This post would have been up a long time ago if I hadn’t had to spent the last week grubbing around for money, and on that subject… the more observant among you might have noticed a paypal donate button just beneath my biography. It never occurred to me that if I ask for money I might get it, but thanks to a very generous blog reader I have learnt that there are, to my astonishment, people prepared to do just this. So if you have spare money kicking around and feel like making my life easier…

Anyway, so by now the cat is out of the bag, and the news isn’t news anymore anyway: the Madagascar pochard Aythya innotata, supposed extinct since 1992 (when the ‘last’ specimen died in captivity), has been rediscovered. Ducks are another of those tetrapod groups that we take for granted and regard as mundane, yet they’re actually a-maz-ing. Before getting into pochards into any detail, let’s remind ourselves how amazing ducks are.

Ducks are amazing

At least some ducks have particularly interesting sex lives, involving over-sized sex organs, gang rape and occasional necrophilia. Some species are bizarrely aggressive*, regularly attacking and beating other waterbirds to death. Some ducks can carry their eggs and/or their juveniles in flight, and some species practise nest parasitism. Herbivory, filter-feeding, carrion-feeding and flightlessness have all been evolved by ducks. Many duck species are amazingly mobile, and consequently have enormous global ranges (an issue which is particularly significant with regard to mallards Anas platyrhynchos and their close relatives and derivatives: a subject I aim to cover at another time). Their mobility is particularly interesting for two reasons. Firstly, it means that they are particularly good at colonising remote islands, and because populations have repeatedly become sedentary after having made a colonisation, ducks have also been good at evolving island endemics. Secondly, it means that ducks excel in transporting things, such as sediment particles and small or microscopic organisms.

* Notably steamer ducks: go here for more.

Ducks – particularly herbivorous species such as pochards – have proven to be highly important transporters of aquatic plants, both as seeds stuck to their feathers or feet (a form of transport known as epizoochory), and as propagules carried in the bird’s gut (a form of transport known as endozoochory). Ostracods and small snails also get transported by ducks, in cases for distances of 30 km or so. The mobility of ducks (and other wildfowl) also has implications for the spread of viruses: recent work indicates that naturally migrating wildfowl were responsible for spreading the HPAI H5N1 virus from Russia and Kazakhstan to eastern Europe (Gilbert et al. 2006).

Anyway, back to pochards. Sometimes called bay ducks, pochards – the tribe Aythyini – are one of four clades that together make up Anatinae, the true duck group (the other anatine clades are Malacorhynchini [pink-eared ducks], Anatini [surface-feeding ducks] and Mergini [seaducks]). Found virtually worldwide, the 17 pochard species are diving ducks with high wing loadings and several specialisations for subaqueous locomotion. Some species do a distinctive leap before diving, and some have to run across the water surface before taking off (others are more typical in being able to leap directly from the water’s surface). Pochards are mostly migratory, breed near permanent bodies of freshwater, and, except three of the scaups, all are predominantly herbivorous.

The sad ‘loss’ of the Madagascar pochard

So back to the latest news from the world of pochards: the amazing rediscovery of the Madagascar pochard, also known as the Madagascar white-eye. First described from Lake Alaotra in central-eastern Madagascar in 1894, it was apparently still common during the 1930s and is even said to have been still common in Soothill & Whitehead’s 1978 Wildfowl of the World. This was incorrect however, as in fact the species hadn’t been found at the lake since 1971 (Young & Kear 2006), and the last published sighting comes from 1970. Furthermore, the 1970 sighting is controversial: it described an observation of the pochard at Lake Ambohibao (near Antananarivo), and as such is (so far as I can tell from the literature) the only sighting made away from Lake Alaotra. Incidentally, pochard bones from Reunion may or may not be anything to do with the Madagascar pochard (Mourer-Chauviré et al. 1999): if the Reunion bones are referable to this species, then it had a far wider range in the recent past than it did in the 19^th and 20^th centuries.

Following the pochard’s decline, thorough searches failed to reveal any trace of its continued presence. However, a publicity campaign amongst villages around Lake Alaotra in 1989 then led to the 1991 capture of a single male. He was kept in captivity, but died in 1992, and little about the biology and behaviour of the species was learnt from the individual. This is unfortunate as the Madagascar pochard is particularly poorly known, though given that its specific name means ‘unremarkable’, you might think that there isn’t much to know about it. We do know that, like other pochards, it feeds by diving, probably for the seeds of water-lilies and other plants and invertebrates.

The Madagascar pochard’s decline and apparent extinction seems predominantly to have resulted from extreme habitat degradation and the introduction of both herbivorous and carnivorous fish (including tilapia and large-mouth bass). Severe deforestation of the local hills has resulted in silting-up of the lake, the consequence of which has been the spread of papyrus marsh, the consequence of which has been the setting alight of the marshes to stop them spreading, the consequence of which has been the inadvertent killing of nesting birds. Carp (introduced in 1926), tilapia (introduced in 1955) and black bass (introduced in 1961) are among several alien fish that now live in Lake Alaotra. These fish appear to compete with native waterbirds by eating the same plants and invertebrates, and the larger, carnivorous fish species may predate upon pochard ducklings. Nylon monofilament gill-nets, hidden by local fishermen in open water or at the bases of aquatic plants, are thought to have seriously affected diving birds, including the pochard as well as grebes (Young & Smith 1989).

Given all these problems, it is not surprising that the pochard declined to apparent extinction. The Alaotra or Delacour’s grebe Tachybaptus rufolavatus [image above, at left], discovered in 1929 and described in 1932, is unique to the lake and also appears to have become extinct (partly due to hybridisation with the African little grebe T. ruficollis capensis). Lake Alaotra is also home to the Alaotra lemur Hapalemur griseus alaotrensis [image at left]: the only primate that spends most of its life in marshland. Confirming the presence or absence of any of these animals, particularly the pochard, is difficult however as ‘the marsh is so extensive and difficult to travel in that the duck could easily go undetected inside it’ (Young & Smith 1989, p. 23).

As an extinct species, the Madagascar pochard would join a long and sorry list of recently extinct wildfowl, many of which were endemic to small islands. Young et al. (1996) listed an amazing 54 wildfowl that have become extinct within the last 10,000 years. Most of these birds are obscure and familiar only to specialists, but a handful have been widely featured in the literature and are relatively familiar. Among the latter is the Pink-headed duck Rhodonessa caryophyllacea [image at left], a highly distinctive pochard of India and Bangladesh, named in 1790 and widely regarded as having gone extinct in the 1930s or 1940s. Given that the Pink-headed duck is – like the Madagascar pochard – a pochard, it bears discussing where it fits within this duck group. Luckily both morphological and molecular analyses have been published on this very issue.

Is Rhodonessa a Netta, or is Netta a Rhodonessa?

In a phylogenetic analysis of skeletal, integumentary and soft-tissue characters, Livezey (1996) concluded that the members of Aythyini fell into four major groups, which in branching order are: the stem or narrow-billed pochards, the redheads, the white-eyes, and the scaup. The Marbled duck Marmaronetta angustirostris was the most basal member of the clade, and also the smallest (at less than 500 g). Basal members of the clade are Palearctic in distribution, and it seems that a number of independent invasions of South America, Africa, Madagascar and Australasia occurred during the group’s history. The grouping of the Pink-headed duck as the sister-taxon of the Red-crested pochard Netta rufina (both species down at the base of Aythyini within the stem pochard clade) led Livezey to argue that the two should be regarded as congeneric. With Rhodonessa coined by Reichenbach in 1853 and Netta by Kaup in 1859, the former supposedly had priority, so the Red-crested pochard – a familiar species to anyone that knows ducks – became renamed Rhodonessa rufina (Livezey 1996) [adjacent image shows male Red-crested pochard].

However, Livezey had made a mistake, as Kaup named Netta in 1829, not 1859, so in later publications he switched things round, now sinking the Pink-headed duck into Netta, and hence renaming it Netta caryophyllacea (Livezey 1997). This hasn’t been widely accepted however. The Pink-headed duck and Red-crested pochard are hypothesised to be sister-taxa, and hence any decision about their generic status is down to opinion about how different, or similar, they are. Are they really similar enough to be lumped together in the same genus? No: they look markedly different, and hence most ornithologists have argued that there’s nothing wrong with retaining separate generic status for both of them.

It’s fairly well known that the Pink-headed duck was really strange. Really, really strange: go here for a higher-res version of the adjacent image. Chocolate brown except for a pink speculum, head and neck, it sported a remarkably strange and unique, long-necked, stiff-necked posture. A short, rounded occipital crest sat at the back of the head; its syringeal bulla was flattened, rather than rounded as in other pochards. Its white, spherical eggs lacked the ‘soapy’ texture characteristic of duck eggs, and its feet resembled those of dabbling ducks more than those of other pochards. Far less appreciated is that the Red-crested pochard is also odd, however, with more recognised autapomorphies than the Pink-headed duck. Features of its syringeal bulla are unique, it has that rounded, bushy head crest, and various details of the plumage on its flanks, wings and neck are unique. In view of all these profound differences it seems most appropriate to keep Rhodonessa and Netta as separate, even if they are more closely related to each other than to other pochards.

The Madagascar pochard returns

[adjacent photo, showing two male Madagascar pochard, by Lily-Arison Rene de Roland]

So, as announced on November 20^th 2006 by The Peregrine Fund – an international conservation group that focuses on raptor-based conservation efforts – the Madagascar pochard has now been officially rediscovered. It really was hiding out, and not extinct. National Director for The Peregrine Fund’s Madagascar Project, Lily-Arison Rene de Roland, and field biologist Thé Seing Sam, observed 13 Madagascar pochards in total, four of which were juveniles (for their photos, please go here). This is great news, as if the right conservation efforts are put in place the bird might be pulled back from the brink of extinction. It also provides hope for species that are possibly extinct, but are both highly cryptic and inhabit remote and difficult areas. Err, like the Pink-headed duck? Hmm, more on that another time.

For the latest news on Tetrapod Zoology do go here.

Refs - -

Gilbert, M, Xiao, X., Domenech, J. Lubroth, J., Martin, V. & Slingenbergh, J. 2006. Anatidae migration in the Western Palearctic and spread of highly pathogenic avian influenza H5N1 virus. Emerging Infectious Diseases 12, 1650-1656.

Livezey, B. C. 1996. A phylogenetic analysis of modern pochards (Anatidae: Aythyini). The Auk 113, 74-93.

- . 1997. A phylogenetic classification of waterfowl (Aves: Anseriformes), including selected fossil species. Annals of Carnegie Museum 66, 457-496.

Mourer-Chauviré, C., Bour, R., Ribes, S. & Moutou, F. 1999. The avifauna of Reunion Island (Mascarene Islands) at the time of the arrival of the first Europeans. Smithsonian Contributions to Paleobiology 89, 1-38.

Young, H. G. & Kear, J. 2006. The rise and fall of wildfowl of the western Indian Ocean and Australasia. Bulletin of the British Ornithologists’ Club 126, 25-39.

- . & Smith, J. G. 1989. The search for the Madagascar pochard Aythya innotata: survey of Lac Alaotra, Madagascar October-November, 1989. Dodo, Jersey Wildlife Preservation Trust 26, 17-34.

- ., Tonge, & Hume, J. P. 1996 Review of Holocene wildfowl extinctions. Wildfowl 47, 166-180.

Those sexy tupuxuarids

2006-11-16T11:19:00.000Z

Thanks to my good friend (and former phd supervisor) Dave Martill, I am finally in possession of my own copy of David Unwin’s 2006 book The Pterosaurs from Deep Time. It’s a handsome, well-illustrated and well-written book literally packed full of data. Given that there are only a handful of books devoted to pterosaurs (the only ones worthy of note are Seeley’s 1901 Dragons of the Air*, Wellnhofer’s 1991 The Illustrated Encyclopedia of Pterosaurs and Buffetaut & Mazin’s multi-authored 2004 Evolution and Palaeobiology of Pterosaurs), the appearance of any new volume on the subject is noteworthy. However, Unwin’s book gets more than an honorary mention: it deserves some serious bigging-up, if you’ll pardon the expression, as it is, frankly, excellent. But what’s odd is that, thus far, I’ve only seen two reviews of it. The first (posted to an internet discussion group) was negative, but its author is notorious for holding a deeply idiosyncratic view of pterosaurs that cannot be, and isn’t, taken seriously. The second, produced by two close acquaintances of mine, is not really negative, but it’s not particularly positive either [adjacent image by Mark Witton, from his flickr site].

* This book is often said to be rare and expensive. Maybe that’s true, but I got mine for £3 in a second-hand book shop.

Given this lamentable situation let me continue with the bigging-up. The Pterosaurs from Deep Time is not, as some have said, a coffee-table book. Yeah, it features some big and highly attractive pictures (both excellent photos of specimens, and colour artwork), but in its thorough coverage of what we know about pterosaur diversity, evolution, biology and lifestyle, it is unparalleled and awesome. If only books like this existed on all the tetrapod groups. Seriously, I am hard pressed to think of any detail about pterosaurs that Unwin has not covered. Todd Marshall’s artwork, scattered throughout the book, is great, with accurate, dynamic animals poised in realistically cluttered, detailed environments. I’ve collaborated with Todd (I advised him when he produced artwork for Usborne’s 2004 World Atlas of Dinosaurs), and I get the impression that he works hard to make fossil animals look like long-time denizens of their environments. Think about it: living animals generally aren’t pristine objects, looking as if they’ve just come out of the pages of a field guide; they are often physically untidy, or dirty. Their colours and surface textures may mimic or even incorporate the sediments and plants of their environment. They often look like they belong. This is the feeling I get from Todd’s animals.

My technical work, back when I could consider myself a palaeontologist (right now I consider myself simply unemployed), was on theropod dinosaurs. But as with so much in life I kept finding myself distracted and spending time on extraneous side projects, and every now and again I’ve dabbled on pterosaurs (e.g., Naish & Martill 2003). During 2004 and 2005, Dave Martill and I spent a lot of time on an unusual Cretaceous pterosaur from Brazil called Tupuxuara. Inspired mostly by the discovery of a new specimen, our research culminated in the 2006 publication of our paper ‘Cranial crest development in the azhdarchoid pterosaur Tupuxuara, with a review of the genus and tapejarid monophyly’. Snappy title, no? There’s lots to say about Tupuxuara: on its phylogenetic relationships and taxonomy, on its feeding behaviour, and on the changes that it underwent during growth. Let’s see how much of this I can get out of the way in what will eventually turn out to be several blog posts.

First described for a partial snout from the Brazilian Santana Formation, Tupuxuara longicristatus Kellner & Campos, 1988 is a toothless Cretaceous pterosaur with a rather long, subtriangular skull. A tall mid-line crest grew like a sail from the dorsal margin of the snout and cranium. It now seems that nearly all of the characters proposed initially to distinguish Tupuxuara from other pterodactyloid pterosaurs are problematic in not being unique to the genus, but in fact Tupuxuara is clearly diagnosable, being unique in having a sort of deep premaxillary crest in which the dorsal margin extends subparallel to the dorsal margin of the nasoantorbital fenestra (Martill & Naish 2006, p. 931). While Tupuxuara is known today from near-complete skeletons (frustratingly, these specimens still await proper description), the good thing about this diagnosis is that it applies even to the 1988 type material.

A second Tupuxuara species, T. leonardii Kellner & Campos, 1994, is also from the Santana Formation and, curiously, was also represented initially only by an incomplete section of snout. A few other tupuxuarid specimens have been reported. A specimen named Santanadactylus spixi Wellnhofer, 1985 is almost certainly a close relative of Tupuxuara (possibly even a member of the genus), despite the fact that it was named as a new species of an ornithocheirid genus (ornithocheirids are long-skulled toothed pterodactyloids closely related to Pteranodon and Nyctosaurus, and not particularly closely related to azhdarchoids). Various taxonomically indeterminate Crato Formation specimens also seem referable to the group. Then there is Thalassodromeus sethi Kellner & Campos, 2002, also from the Santana Formation of Brazil. Thalassodromeus is, supposedly, distinct from Tupuxuara, but this is debatable. More on this issue another time [adjacent Tupuxuara skull image from the pterosaurier site].

Finally, a pterosaur snout and lower jaw from the late Maastrichtian Javelina Formation of Texas, illustrated in Wellnhofer’s Illustrated Encyclopedia of Pterosaurs and labelled therein as Quetzalcoatlus, also seems to be a tupuxuarid and possesses a snout morphology highly similar to that regarded as diagnostic for Tupuxuara. This is really interesting for a few reasons. It shows that tuxupuarids existed in North America as well as South America, and also shows that they survived until late in the Cretaceous. Virtually all Maastrichtian pterosaurs are azhdarchids and it is implied by some that this was the only pterosaur group to make it to this time. If the Javelina Formation specimen really is a tupuxuarid, it indicates that at least one other pterodactyloid clade survived this late.

What sort of pterosaur is Tupuxuara? Based mostly on characteristic features of the skull and hand, there is universal agreement among pterosaur experts that Tupuxuara is an azhdarchoid: that is, a close relatives of the azhdarchids – those large to enormous long-necked pterodactyloids that, I argue, most likely lived a stork-like lifestyle. But, among azhdarchoids, is Tupuxuara particularly close to azhdarchids, or is it actually more closely related to the bizarre, shorter-skulled Tapejara? Here we come to a fundamental disagreement among pterosaur experts.

Pointing to similarities in the shape of the orbit, snout tip and crest, and the anatomy of the coracoid, Alex Kellner (2003a, b, 2004) has argued that Tapejara and Tupuxuara should be united as the Tapejaridae. Conversely, noting derived characters in the hand and skull seen in Tupuxuara and azhdarchids but not in Tapejara, Unwin (2003) has proposed that Tupuxuara forms a clade with the azhdarchids (dubbed Neoazhdarchia), rather than one with Tapejara. Several recently described azhdarchoids complicate this area. Sinopterus and Huaxiapterus, both with two species each (all from the Lower Cretaceous of China), appear intermediate in some respects between Tapejara and azhdarchids, and the supposed Tapejara species T. navigans is also more like azhdarchids in some details than it is like the type species of Tapejara, T. wellnhoferi.

In a new evaluation of the characters employed in this debate, Dave and I concluded that the concept of Neoazhdarchia is better supported than the idea of a Tapejaridae that includes Tupuxuara (Martill & Naish 2006). Note, however, that our cladistic analysis is weak with a small data set. Furthermore, while we didn’t find Tupuxuara to group together with Tapejara, we did sometimes find Tapejara to group together with Sinopterus. While Kellner’s concept of Tapejaridae may be paraphyletic, it therefore seems that there is a clade that we should call Tapejaridae: it includes Tapejara wellnhoferi, Sinopterus and Huaxiapterus. A subsequent study came to the same conclusion (Lü et al. 2006).

What I found particularly interesting is that we didn’t find the several Tapejara species to group together, but this isn’t surprising given how distinct they are. The type species, T. wellnhoferi, is relatively short-skulled and with a modest bony crest and just a short bony projection at the skull’s rear margin. T. imperator and T. navigans, in contrast, are longer-skulled, with immense vertical crests, supported by thin subvertical spines at their leading edges. A really long bony spike projects backwards from the skull’s rear margin in T. imperator. A study due to be published soon revises the taxonomy of these supposed close relatives: more news on that when it appears [adjacent image shows T. imperator. Yet again borrowed from Mark Witton’s flickr site. Sorry Mark].

And I’ll have to stop there. Given that the main point of Martill & Naish (2006) was to document ontogenetic changes that occurred in Tupuxuara – changes linked to the probable use of the cranial crest as a sexual signal – it’s ironic that I haven’t covered this story here, but I will in future. And, as I said, there’s also the debate about tupuxuarid feeding biology and so on. And don’t worry if you’re hoping to see more on phorusrhacids – I haven’t finished with them yet. Stuff on British dinosaurs coming soon. Oh yeah – pdfs of both Naish & Martill (2003) and Martill & Naish (2006) are available, feel free to ask and I can send them.

For previous posts on pterosaurs see Pterosaur wings and Why azhdarchids were giant storks. Posts on tupuxuarids have been promised for a while: see Attack of the blue foamy pterosaurs. For those interested, we are now at 33 ‘100 year’ European mammals. For the latest news on Tetrapod Zoology do go here.

Refs - -

Kellner, A. W. A. 2003a. Pterosaur phylogeny and comments on the evolutionary history of the group. In Buffetaut, E. & Mazin, J.-M. (eds) Evolution and Palaeobiology of Pterosaurs. Geological Society Special Publication 217. The Geological Society of London, pp. 105-137.

- . 2003b. Comments on the phylogeny of the Pterodactyloidea. Rivista del Museo Civico di Scienze Naturali “Enrico Caffi” 22, 31-37.

- . 2004. New information on the Tapejaridae (Pterosauria, Pterodactyloidea) and discussion of the relationships of this clade. Ameghiniana 41, 521-534.

Lü, J., Jin, X., Unwin, D. M., Zhao, L., Azuma, Y. & Ji, Q. 2006. A new species of Huaxiapterus (Pterosauria: Pterodactyloidea) from the Lower Cretaceous of western Liaoning, China with comments on the systematics of tapejarid pterosaurs. Acta Geologica Sinica 80, 315-326.

Martill, D. M. & Naish, D. 2006. Cranial crest development in the azhdarchoid pterosaur Tupuxuara, with a review of the genus and tapejarid monophyly. Palaeontology 49, 925-941.

Naish, D. & Martill, D. M. 2003. Pterosaurs – a successful invasion of prehistoric skies. Biologist 50 (5), 213-216.

Unwin, D. M. 2003. On the phylogeny and evolutionary history of pterosaurs. In Buffetaut, E. & Mazin, J.-M. (eds) Evolution and Palaeobiology of Pterosaurs. Geological Society Special Publication 217. The Geological Society of London, pp. 139-190.

Giant killers: macropredation in lions

2006-11-14T11:15:00.003Z

By now you have probably heard that episode 2 (‘Great Plains’) of the BBC’s series Planet Earth (currently in its second series) included amazing footage of the elephant-killing lions of Savuti in Chobe National Park, northern Botswana. While most people ‘know’ that elephants are immune to predation thanks to their size, nobody has told this to the Savuti lions. Hunting at night, when the elephant’s poor night vision puts them at a major disadvantage, the lions co-operate as a pride of about 30 individuals to bring down and dispatch elephant prey. It is amazing. But, as usual, the media is leading us all horribly astray.

We should make clear to begin with that these are not just any old lions, behaving spontaneously or opportunistically: they are a specialised, highly experienced population that have, uniquely, become elephant killers. While there are some major questions as to how the Savuti lions learnt to do this, Planet Earth didn’t, unfortunately, touch on how old this culture is, or how it originated. It is thought that the Savuti lions have learnt over time to kill bigger and bigger prey, each time winning success by the virtue of their large pride size. Lions elsewhere can – opportunistically – kill Cape buffalo Syncerus caffer* (weighing c. 1000 kg) and sometimes hippo Hippopotamus amphibious (c. 1500-3500 kg), and it has been speculated that, after learning to successful tackle and kill hippo, the lions became bold enough to begin regularly taking juvenile elephants, eventually moving up to adults. And if you’re wondering: YES, the Savuti lions have been recorded attacking and killing adult elephants.

* Though note that some lion populations are specialist buffalo-killers. In Tanzania’s Lake Manyara National Park, George Schaller (1972) reported that an amazing 62% of all lion prey was made up of Cape buffalo, with 81% of this 62% being adult male buffalo. Buffalo-killing is also important to the lions of Kruger National Park, and studies here have shown, significantly, that male lions are not just frequent and successful hunters: they are also the lions that are best at killing buffalo (Funston et al. 1998).

A few opportunistically recorded events may have encouraged the lions to view elephants as potential prey. In their National Geographic film Ultimate Enemies, wildlife film-makers Dereck and Beverly Joubert recorded a case where, after a fight with another bull, a defeated elephant lay, wounded, on the ground. Understandably, the elephant’s misfortune became the hungry lion pride’s gain. Wildlife photographer and travel writer Leigh Kemp recorded a case where an old, weakened bull that collapsed and became unable to stand was discovered and eaten (while still alive) by opportunistic lions. It is tempting to suggest that these events and others like them might have been catalysts in encouraging the development of elephant-killing in the Savuti lions. Numerous other instances of elephant-killing have been filmed and documented by the Jouberts, and in 1997 they published a book covering this behaviour in depth (The Lions of Savuti: Hunting with the Moon, published by National Geographic).

The Lions of Savuti: Hunting with the Moon records something like 15 years of observations, and even in 1990 the Jouberts were estimating that about 20% of the Savuti lion’s diet was made up of elephant. I would love to know if the behaviour goes back further than this, as personally I find it highly unlikely that this behaviour really is something that the lions have ‘just learnt’. Historically, Africa was filled with a lot more lions than it is now, not to mention elephants, and given the extraordinary behavioural flexibility of lions* I suspect that elephant-killing is something that lions have practiced many many times in the near and distant past.

* If you’re read Bruce D. Patterson’s outstanding The Lions of Tsavo (Patterson 2004) you’ll know that studies of the Serengeti-type lion that we’re all so familiar with (e.g. Schaller 1972) have ‘created an orthodoxy around lion biology that applies poorly to the species elsewhere’ (p. 138).

The fact that the Jouberts were photographing and filming this behaviour negates one of the claims that have appeared as a result of Planet Earth’s coverage: this being that the BBC were the first to film this behaviour (not that anyone working for the BBC has said this, so far as I can tell). In fact Ultimate Enemies, showing scenes of night-time elephant predation by Savuti lions, was broadcast in North America in 2004. This is not to downplay the BBC’s commendable efforts, however, and it is clear that obtaining the sort of footage they did is tremendously time-consuming, dangerous, and requires a monumental amount of effort. With panicked elephants lumbering around in the dark, and surrounded by hungry and aggressive lions that routinely kill animals weighing many hundreds of kilos, the camera teams were in the middle of the bush, in the middle of the night, in small jeeps with open sides and windows.

What did we actually get to see? The answer to this is both positive and negative. To begin with, it seems that the lions used psychological warfare to intimidate and confuse the elephants: loud roaring in the dark. This behaviour has been recorded in other lion populations and also in leopards, and it seems that the idea is to scare prey into making an ill-thought dash for ‘safety’. Paying particular attention to juvenile and adolescent elephants, especially those that were separated from the rest of the herd, the lions were then shown attacking the hind legs and haunches of fleeing elephants, biting and clawing and hanging on to the pursued animal. And that… is about it. Here’s where we come to the negative, particularly problematic, part of this whole story.

We empathise with elephants. And, somehow, seeing them being killed and eaten by big cats is, for many people, just wrong. That may or may not be a justifiable point of view, but what is undeniable is that elephant-killing is protracted, unpleasant, and gory. Consequently almost none of the actual killing was shown. By clawing and biting at the elephant’s legs, the lions hamstring a chosen elephant, and also use the combined weight of multiple individuals to bring it down. This apparently happens surprisingly quickly. From spotting an elephant, to pursuing it, to getting it to collapse: all can take as little as 30 seconds. Once an elephant is down, some of the lions work on clamping its trunk shut, and I presume that they might also attack the throat and mouth. Like it or not, we can assume that lions at the other end of the animal will now begin feeding. The elephant might take about 30 minutes to die. It does not sound nice, or look nice.

I empathise with elephants, and do not enjoy the thought of them being killed. But the fascination that I have for animals makes me want to know more about what actually happens. This is a natural act of predation: sure, it’s not pleasant, or pretty, but I want to know what happens. For me, the footage was ultimately disappointing, then, in showing bugger all (worth noting here is that views on the screening of acts of predation are starting to change. See Finally: big cat kills uncensored and uncut).

What makes this all the more frustrating is the implication from some that the lions are downright nasty, committing an evil, murderous act that is heinous and unjust. An article – titled ‘The killing fields’ – that appeared in Times2 (a supplement to the British newspaper The Times) described the footage as ‘possibly the most shocking natural history footage you will have seen’. It went on to state that ‘If you have any sentimental feelings about lions, prepare to lose them’. I’m sorry, but that’s crap. The appreciation I have of lions and their amazing behavioural flexibility and unique social system is increased by the knowledge that they have learnt to kill elephants. Yes it’s gory, and – no doubt about it from our point of view – upsetting and even horrific, but it is an amazing thing that we should wonder at.

Coming eventually: agamas, tupuxuarids, fake Chinese turtles, temnospondyls for beginners, kinglets and the passerine supertree, more on sea snakes, anguids, giant eagles and plethodontids, those lost tree frogs, storks and (one day) rhinogradentians. For many of these posts you'll have out check Tetrapod Zoology at its new location here.

Refs - -

Funston, P. J., Mills, M. G. L., Biggs, H. C. & Richardson, P. R. K. 1998. Hunting by male lions: ecological influences and socioecological implications. Animal Behaviour 56, 1333-1345.

Patterson, B. D. 2004. The Lions of Tsavo: Exploring the Legacy of Africa’s Notorious Man-Eaters. McGraw-Hill, New York.

Schaller, G. 1972. The Serengeti Lion. University of Chicago Press, Chicago.

Goodbye, my giant predatory, cursorial, flightless hoatzin

2006-11-12T20:25:00.000Z

Toxic Madagascan frogs are losing their toxicity, there is that ongoing controversy about the taxonomic status of the kouprey, and there have lately been some bizarre criticisms of Jeff Meldrum and his sasquatch research. One day I’ll build up enough courage to post about sasquatch, but not yet :) I am still planning to blog about Kimmeridge Clay dinosaurs and the elephant-killing lions of Chobe National Park (Botswana), not to mention temnospondyls. On a personal level, my life continues to go from bad to worse and I have been horribly ill over the past several days, but you don’t want to hear about that. Oh yeah, our house is being literally invaded by harlequin ladybirds (an alien species from Asia that arrived in Britain in 2004).

Anyway, as you’ll note from the accompanying image, I still plan for now to write about things that are related to, or inspired by, Chiappe & Bertelli’s recent paper on phorusrhacids. The image, depicting the controversial North American phorusrhacid Titanis, has been kindly provided by my good friend Carl Buell who has, I am very pleased to say, recently started blogging again after a very long absence.

In the previous post – a spinoff of a still earlier post about phorusrhacids – I discussed the South American landbird theory. It suggests that….

… there might be a hoatzin-cariamaen clade, probably persisting as relicts in South America but more widespread during the early Cenozoic. It may perhaps involve turacos, and perhaps also falcons. Finally, New World vultures (which have all their earliest fossil occurrences in the Old World) might be allies of the South American landbird group.

Support for this idea comes mostly from the similar hand morphology that some of these birds have, combined in part with the idea that they’re just about similar enough to be imagined as possible relatives. But if you’re only familiar with the view of bird classification presented in textbooks and so on, the idea that cariamaens might be close to such things as hoatzins is pretty surprising, as the former have conventionally been regarded as part of Gruiformes, the group that includes rails, cranes, trumpeters and several other groups. As mentioned in the previous post, there are substantial doubts however as to whether Gruiformes is monophyletic or not. What is the current thinking on this issue?

Dissipation of the gruiforms

In their comprehensive and influential study of DNA hybridization, Sibley & Ahlquist (1990) supported gruiform monophyly, as did Livezey (1998) in a large study of morphological data, and Cracraft et al. (2004) on genetic data. However, other large-scale studies have found different gruiforms to occupy different positions within the neornithine tree (in the following discussion I have not aimed to be comprehensive: rather, I am most interested in those studies that included seriemas [and hence provide data on the position of cariamaens]).

In a major and comprehensive study of morphological characters, Livezey & Zusi (2001) found gruiforms to be scattered about the neornithine tree. Seriemas were without close relatives and were the most basal group within Neoaves (the neognath clade that excludes waterfowl and gamebirds), bustards [see adjacent image] were on their own and near the middle of the neoavian radiation, trumpeters, cranes and limpkins grouped with hoatzins in a clade that also included flamingos, tubenosed seabirds, divers and penguins, and rails and finfoots were members of a ‘higher landbird’ clade. It should be noted that their paper is preliminary and that further studies (hopefully with better-resolved trees) will emerge from the immense amount of data that Livezey & Zusi collected. They noted in particular that the unusual positions they recovered for seriemas and other gruiforms were likely to change in future (p. 195).

In a study of osteological and soft-tissue characters, Mayr & Clarke (2003) also found gruiforms to be polyphyletic: rails, trumpeters and cranes (referred to from hereon as the ‘gruiform core’) were one of the most basal groups within Neoaves, bustards were without close relatives, and seriemas formed a clade with….. hoatzins. The seriema-hoatzin clade was closely allied with a cuckoo-turaco clade. The main characters tying seriemas, hoatzins, cuckoos and turacos together were those of the hand and the hip muscles, and they were also united in possessing distinctive recesses on the top of the pelvis. From the point of view of the South American landbird theory, Mayr & Clarke’s study is therefore significant in finding empirical character support for the monophyly of a turaco-hoatzin-seriema clade. However…

In a much-discussed study, Fain & Houde (2004) found that Neoaves consisted of two clades, Metaves and Coronaves. Their most exciting conclusion was that rampant convergence had occurred between these two parallel radiations: metavians include hoatzins, mesites and grebes, while coronavians include turacos, passerines and divers, for example (if those lists are lost on you, hoatzins are similar to touracos, mesites are similar to some passerines, and grebes are similar to divers). Different gruiforms were found to belong to both groups; mesites, kagus and sunbitterns were metavians close to owlet nightjars, grebes and sandgrouse; seriemas and bustards were coronavians without close relatives; while the gruiform core was part of a coronavian clade that included divers, cuckoos, turacos, tubenosed seabirds, storks, herons, penguins and pelicans.

Most recently, Ericson et al. (2006), in a study of molecular sequence data, also supported gruiform polyphyly. Their study is significant in that they found support for Fain & Houde’s Metaves-Coronaves division, and the gruiform groups fell into pretty similar positions, though with exceptions. Seriemas were not isolated within Coronaves (as they were in Fain & Houde’s study), but instead part of a clade that included parrots, passerines and falcons.

An approximate consensus

It’s difficult to conclude from these conflicting studies (and others) that we are anywhere near a consensus on neoavian affinities, but in fact we are getting somewhere, and the following details are common to all the recent major studies; gamebirds and waterfowl are at the base of Neornithes, and probably form a clade (Galloanserae) that is the sister-taxon to Neoaves; within Neoaves, tubenosed seabirds, pelicans, divers, herons and storks are part of a waterbird clade somewhere near the base of Neoaves; shorebirds (gulls, terns, skuas, auks, plovers and waders) form another clade near the base of Neoaves; and there is a ‘higher landbird’ clade that includes passerines, woodpeckers and allies, kingfishers and rollers. Owls, raptors, mousebirds, parrots, trogons, hornbills and hoopoes are most likely close to, or part of, the ‘higher landbird’ clade. Finally, there might be a hitherto overlooked metavian clade at the base of Neoaves: it includes such strange bedfellows as nightjars and other nightbirds, swifts and hummingbirds, kagus, pigeons, sandgrouse, flamingos and grebes, mesites, hoatzins and tropicbirds.

The accompanying cladogram is a highly simplified attempt at depicting this consensus.

The idea that the hoatzin is not close to seriemas or turacos, but is in fact a member of a hitherto-overlooked metavian clade at the base of Neoaves is an exciting one, mostly because it would make this bird strongly convergent on the coronavian turacos. What do other studies have to say about the affinities of the hoatzin?

The hoatzin problem

Unfortunately the phylogenetic affinities of the hoatzin have been one of the most contested issues within avian systematics (there is an entire review article devoted to this subject: Sibley & Ahlquist 1973). Most usually considered close to either gamebirds or cuckoos (in fact, when first described in 1776 the hoatzin was classified as a species of Phasianus), hoatzins have also been allied over the years with turacos, rails, hornbills, sandgrouse and pigeons. Sibley & Ahlquist (1973) concluded that the hoatzin was not just closely related to cuckoos, but actually deeply nested within Cuculidae. This idea has been challenged by other studies, all of which find hoatzins to be outside of Cuculidae (Hughes & Baker 1999, Hughes 2000, Johnson et al. 2000), and the link with turacos has been better supported. The young of both groups clamber about among branches using their clawed fingers*, and exhibit stunted outer primaries that allow them to do this. They also share details of pterylography and soft tissue and skeletal anatomy, plus they’re generally alike in behaviour and ecology.

* Claims that young hoatzins do not use their clawed fingers in climbing (and that they rely on the bill and feet alone) are not correct. I’ve never seen a live hoatzin, but there are many photos and bits of footage showing them climbing with their fingers.

Arguing that ‘the hoatzin problem is still unresolved’, Sorenson et al.’s (2003) new analysis of mtDNA showed that there was little or no support for the linking of hoatzins with either turacos or cuckoos, and that their data best supported an affinity between hoatzins and columbiforms (pigeons and doves). While several early avian systematists also linked hoatzins with columbiforms, Sorenson et al. (2003) noted that their results were poorly supported. Interestingly, a louse (Osculotes) unique to the hoatzin does not have any close relatives among the lice that occur on cuckoos or turacos. Of special interest to our discussion here is that Sorenson et al. (2003) didn’t include any gruiforms in their study, and hence didn’t/couldn’t test the possibility that hoatzins might be allied to any of the taxa included within that group.

Worth noting is that, while there are two fossil hoatzins, neither of them preserve enough information to tell us anything useful about hoatzin affinities, or about the way of life of the fossil forms. Hoazinoides from the Miocene of Colombia, known from a partial skull, seems to have been very similar to Opisthocomus while Onychopteryx from the Eocene of Argentina is known only from a partial tarsometatarsus and hence is not too informative.

In conclusion; Sibley & Ahlquist’s (1973) idea that hoatzins are cuckoos has now been rejected; Sorenson et al.’s (2003) conclusion that hoatzins are close to columbiforms is both poorly supported and unsatisfactory in that too few other neornithine taxa were included for comparative purposes; and studies linking hoatzins with turacos (Hughes & Baker 1999, Hughes 2000) are now questionable given that there is strong evidence from the β-fibrinogen gene that hoatzins are part of a metavian clade that does not include turacos (Fain & Houde 2004, Ericson et al. 2006).

Goodbye, my giant predatory, cursorial, flightless hoatzin

After all this then, how seriously should we take the idea that the South American landbird group is real? While recent phylogenetic studies strongly indicate that gruiforms are not monophyletic, only one large-scale study (Mayr & Clarke 2003) has found support for a clade that corresponds roughly with the South American landbird group. More recent studies, with larger data sets, have failed to group any of these birds however, and in fact hoatzins and seriemas seem to be at different ends of the neornithine tree.

In the most recent word on the subject, Ericson et al. (2006) found molecular sequence data to support a grouping of seriemas within a clade that included parrots, passerines and falcons. Is this where phorusrhacids and their relatives will finally go then? As always, we await future work, but if this view is valid, then seriemas, phorusrhacids and other cariamaens most likely evolved from small, arboreal coronavians. Their terrestrial, cursorial adaptations would then be late-evolved novelties, and not primitive features inherited from earlier neornithines.

As with any idea in science, it’s possible of course that future investigation or discovery will provide new data that supports the idea that cariamaens, hoatzins and so on are all close relatives. But for now we can reject it as poorly supported and far less well supported than other views on neornithine phylogeny. Like so many alternative theories, the South American landbird theory hinges on just a few characters that are swamped by a larger number of characters that convey a different signal. So, as appealing as it might be to imagine that condors, caracaras, turacos and hoatzins are all close kin of phorusrhacids, it really is all vague and sadly lacking in any sort of good character support. Oh well.

PS - as I write I am half-watching episode II of series 2 of the BBC’s Planet Earth. While looking at the wildlife of the Tibetan Plateau, they just featured Tibetan groundpeckers Pseudopodoces humilis, and they also just featured a Lesser florican Sypheotides indica, the bustard species pictured above.

Refs - -

Cracraft, J., Barker, F. K., Braun, M., Harshman, J., Dyke, G. J., Feinstein, J., Stanley, S., Cibois, A., Schikler, P., Beresford, P., García-Moreno, J., Sorenson, M. D., Yuri, T. & Mindell, D. P. 2004. Phylogenetic relationships among modern birds (Neornithes): towards an avian tree of life. In Cracraft, J. and Donoghue, M. (eds), Assembling the Tree of Life, pp. 468-489.

Ericson, P. G. P., Anderson, C. L., Britton, T., Elzanowski, A., Johansson, U. S., Källersjö, M., Ohlson, J. I., Parsons, T. J., Zuccon, D. & Mayr, G. 2006. Diversification of Neoaves: integration of molecular sequence data and fossils. Biology Letters doi:10.1098/rsbl.2006.0523

Fain, M. G. & Houde, P. 2004. Parallel radiations in the primary clades of birds. Evolution 58, 2558-2573.

Hughes, J. M. 2000. Monophyly and phylogeny of cuckoos (Aves, Cuculidae) inferred from osteological characters. Zoological Journal of the Linnean Society 130, 263-307.

- . & Baker. Phylogenetic relationships of the enigmatic hoatzin (Opisthocomus hoazin) resolved using mitochondrial and nuclear gene sequences. Molecular and Biological Evolution 16, 1300-1307.

Johnson, K. P., Goodman, S. M. & Lanyon, S. M. 2000. A phylogenetic study of the Malagasy couas with insights into cuckoo relationships. Molecular Phylogenetics and Evolution 14, 436-444.

Livezey, B. C. 1998. A phylogenetic analysis of the Gruiformes (Aves) based on morphological characters, with an emphasis on the rails (Rallidae). Philosophical Transactions of the Royal Society of London B 353, 2077-2151.

- . & Zusi, R. L. 2001. Higher-order phylogenetics of modern Aves based on comparative anatomy. Netherlands Journal of Zoology 51, 179-205.

Mayr, G. & Clarke, J. 2003. The deep divergences of neornithine birds: a phylogenetic analysis of morphological characters. Cladistics 19, 527-553.

Sibley, C. G. & Ahlquist, J. E. 1990. Phylogeny and Classification of Birds: A Study in Molecular Evolution. Yale University Press, New Haven.

- . & Ahlquist, J. E. 1973. The relationships of the hoatzin. The Auk 90, 1-13.

Sorenson, M. D., Oneal, E., García-Moreno, J. & Mindell, D. P. 2003. More taxa, more characters: the hoatzin problem is still unresolved. Molecular Biology and Evolution 20, 1484-1499.

Giant hoatzins of doom

2006-11-03T11:14:00.000Z

Inspired by the recent description of a new and exciting phorusrhacid – a giant predatory South American landbird – I have lately been producing various blog posts on members of this group, as you’ll know if you’re a regular reader. See Terror birds and More on phorusrhacids. There is lots more to say: I am planning also to blog about phorusrhacid skull and hand anatomy, and about their alleged survival into near-modern times. The horrible danger is that the distractions that constantly arise will cause me to veer off at a tangent, and already the paper on the British dinosaurs of the Kimmeridge Clay that Dave Martill, Sarah Fielding and I have finally had published has me wanting to move on to something else. I am also desperate to blog about the lions of Chobe National Park (Botswana), as their ability to kill adult elephants has finally been filmed and is due to be screened on TV next week. Furthermore, there is that AMAZING discovery of a bottlenose dolphin with a perfect pair of miniature hind-flippers (go here), and there is that Mantellisaurus thing. Stay tuned.

While I’m here I want to note some recent updates I’ve made to some articles. Firstly, thanks to comments that have been added by anonymous mammalogists (PLEASE leave your name when you leave a comment), I’ve done some minor updating to The first new European mammal in 100 years? We are now at 31 ‘100 year’ mammals. Secondly, inspired by some questions from Mark Abuys, I have also added some new comments to Graeme’s Pleistocene megafrog. Mark was interested in my mention of the carn-pnay, a crypto-frog from New Guinea with an alleged length of 30 cm.

To return to phorusrhacids...... in the previous posts I at least alluded to ideas about their affinities: it is universally agreed that their closest living relatives are the South American seriemas (or cariamids), and it is furthermore agreed that two fossil groups, the bathornithids of Eocene-Miocene North America and the idiornithids of Eocene-Oligocene Europe, are also close relatives of both seriemas and phorusrhacids. Several features unite these birds (Mayr 2002). They all have a strongly hooked bill, a simple, block-like hypotarsus (a site of ligament attachment on the posterior surface of the tarsometatarsus), distinctively proportioned toe bones, and a laterally compressed, strongly curved and sharp-tipped claw on the second toe (discussed previously here). All of these birds – idiornithids, bathornithids, cariamids and phorusrhacids – form a clade termed the Cariamae Fürbringer, 1888, and conventionally they’ve been regarded as part of Gruiformes, the group that includes rails, cranes, trumpeters and several other groups. A few other fossil groups have been suggested to be part of Cariamae, like the cunampaiids of Eocene Argentina.

Are cariamaens really close allies of rails and cranes? Storrs Olson (1985, p. 143) wrote that the classification of cariamaens within Gruiformes was ‘largely by default, as they do not clearly seem to belong in any other order’, and there is a long-running disagreement among ornithologists as to whether gruiforms are a natural group or not. We’ll look at this issue in the next post.

The South American landbird hypothesis

If you’re a regular reader of this blog you’ll know that I’m a big fan of ‘alternative’ theories on phylogenetic relationships (see, for example, We flightless primates). While I always find these ideas interesting, note the caveat that I do not necessarily endorse them: in fact they often turn out to be poorly supported or spurious. As it happens, one of my favourite ‘alternative’ theories involves cariamaens: it is the South American landbird hypothesis.

Based predominantly on the morphology of the carpometacarpus, some ornithologists have proposed that cariamaens are closely related to the Hoatzin* Opisthocomus hoazin**, that bizarre folivorous, arboreal bird that (uniquely among birds) practices foregut fermentation. In contrast to those of most other neornithines, the carpometacarpi of cariamaens and hoatzins possess a particularly broad, strongly bowed third metacarpal. This is also true of turacos and some cuckoos (indeed, many ornithologists have proposed that hoatzins might be close allies of turacos and/or cuckoos).

* Like ‘fossa’ and ‘sifaka’, ‘hoatzin’ is one of those words that is, apparently, not pronounced the way in which it is written. Some sources state that it is properly pronounced ‘watson’.

** That’s not a typo. Furthermore, the name Opisthocomus cristatus, used by some authors relatively recently (e.g., Chatterjee in The Rise of Birds) was coined (so far as I can tell) by Johann Illiger in 1811 and thus post-dates Statius Muller’s 1776 publication of the name Phasianus hoazin (that’s right - the hoatzin was originally described as a type of pheasant).

Hoatzin and seriema skeletons are also somewhat similar overall: I suppose you could believe that seriemas (and hence other cariamaens) are just big, long-legged hoatzins, modified for a cursorial, raptorial lifestyle whereas the various modifications possessed by hoatzins reflect their folivorous lifestyle (these features include a bizarre sternum where the keel is virtually absent anteriorly, thereby allowing room for the huge crop, and a notably deep, short pelvis) [the adjacent photos show, from top to bottom, a hoatzin skeleton, and a Cariama cristata skull and partial postcranium. Sorry the hoatzin photo is so bad]. Hoatzins and seriemas also possess a few bony and soft-tissue characters that are shared only by these birds, turacos and cuckoos: these include details of the hip musculature and the presence of distinctive bony recesses on the top of the pelvis.

Olson (1985) supported the possible monophyly of the South American landbird group, writing ‘the seriemas and hoatzins appear to be part of an early radiation of primitive land birds, members of which have persisted in South America, perhaps as a result of its isolation’ (pp. 143-144). He further suggested that falcons ‘probably represent a raptorial branch of this radiation’ (p. 144), a suggestion presumably based on the anatomy of caracaras. Note that falconids are essentially a South American group (only a few, recently evolved genera have left the continent). A few fossil taxa might also be interpreted as providing support for the monophyly of this group. Mourer-Chauviré (1983) regarded idiornithids as similar to both seriemas and hoatzins and her conclusions are similar overall to those of Olson (1985). Incidentally, both Olson and Mourer-Chauviré came up with the same idea independently. A long delay in publication meant that Olson (1985) came out after Mourer-Chauviré (1983), by which time Olson decided not to rewrite his text: ‘partly out of laziness and frustration but more to show that we arrived independently at the same basic conclusions’ (p. 151).

Among the most enigmatic of Cenozoic fossil birds is Foro panarium (image at left) from the Eocene Green River Formation of Wyoming: it seems to combine features of hoatzins, cuckoos and turacos but, interestingly, is also superficially raptor-like. This could be used to provide tentative support for Olson’s idea that falcons might be linked to hoatzins and other South American landbirds.

We saw above that hoatzins have often been linked with turacos, and that turacos share with hoatzins and seriemas that unusual and distinctive robust, bowed third metacarpal, as well as other characters. Might turacos also, then, be members of the South American landbird group? True, they aren’t South American but African (though with fossil representatives in Europe). In what might be regarded as a deviant version of the South American landbird group theory, Chandler (1997) proposed that turacos were the sister-taxon to Cariamae. In a novel twist, he further announced that New World vultures (vulturids, aka cathartids) were the next closest relatives of the turaco-cariamaen clade. He noted that fossils, osteology and preliminary biochemical data all provided supportive evidence for this novel hypothesis, though unfortunately he only ever published an abstract on it, and a full paper has yet to appear.

Based – it has to be said – on just a handful of detailed morphological characters, combined with some inference based on biogeography and superficial similarity, the South American landbird group theory suggests the following: that there might be a hoatzin-cariamaen clade, probably persisting as relicts in South America but more widespread during the early Cenozoic. It may perhaps involve turacos, and perhaps also falcons. Finally, New World vultures (which have all their earliest fossil occurrences in the Old World) might be allies of the South American landbird group. I am deliberately avoiding bringing in cuckoos and accipitrids (the latter noted by Olson as being possible allies of the turacos) in order to keep things simple-ish. Furthermore, the South American trumpeters (psophiids) share a number of characters with cariamaens and have also been regarded as part of this story by some authors.

Predictably, I cannot help but find the idea that condors, caracaras, turacos and hoatzins are all close kin of phorusrhacids highly appealing, but it does all seem very vague and sadly lacking in good character support. So, do larger studies – those incorporating molecular and/or morphological information from lots of taxa – support a possible link between these birds? See the next post (Goodbye my giant predatory, cursorial, flightless hoatzin).

For the latest news on Tetrapod Zoology do go here.

Refs - -

Chandler, R. M. 1997. New discoveries of Titanis walleri (Aves: Phorusrhacidae) and a new phylogenetic hypothesis for the phorusrhacids. Journal of Vertebrate Paleontology 17 (supplement to 3), 36-37.

Mayr, G. 2002. A new specimen of Salmila robusta (Aves: Gruiformes: Salmilidae n. fam.) from the Middle Eocene of Messel. Paläontologische Zeitschrift 76, 305-316.

Mourer-Chauviré, C. 1993. Les Gruiformes (Aves) des Phosphorites du Quercy (France). 1. Sous-ordre Cariamae (Cariamidae et Phorusrhacidae). Systématique et biostratigraphie. Palaeovertebrata 13, 83-143.

Olson, S. L. 1985. The fossil record of birds. In Avian Biology, Volume III, pp. 79-238.

Dinosauroids revisited

2006-11-02T14:25:00.000Z

Pretty much everyone interested in dinosaurs, in the history of life, or in such matters as the evolution of intelligence and/or brain size, will be familiar with the various speculations on ‘humanoid dinosaurs’ that have made their way into the literature. During the 1970s it became widely accepted that one group of Cretaceous theropods – the troodontids (known at the time as saurornithoidids) – were relatively big-brained, with encephalisation quotients overlapping those of modern birds and mammals. In reality, troodontids might therefore have been as ‘smart’ as bustards, emus or opossums. The notion that these dinosaurs were ‘big brained’ and therefore ‘intelligent’ seems to have given rise to a myth however: that these were really smart dinosaurs, approaching the anthropoid level in terms of their ability to solve problems and understand the world around them. At least one book on earth mysteries and the paranormal states that some dinosaurs were ‘probably as intelligent as primitive man’ – a quote almost certainly based on studies of troodontids. In Jurassic Park, the dromaeosaurids are intellectually on par with chimpanzees.

Inspired by new data on troodontid brain size, Carl Sagan speculated about intelligent dinosaurs in The Dragons of Eden (1977) and posed the question: what if non-avian dinosaurs hadn’t become extinct? If Cretaceous forms were already so ‘smart’, what would have happened given another 60-odd million years of evolution? His question seems to have inspired a number of science fiction stories that appeared soon afterwards. Among the most important data on troodontid brain size was that published by Dale Russell, then of the National Museum of Natural Sciences (Ottawa), and besides publishing several key studies on troodontid anatomy and functional morphology, in 1982 he did a rather peculiar thing. Co-operating with taxidermist and model maker Ron Séguin, he produced the article ‘Reconstruction of the small Cretaceous theropod Stenonychosaurus inequalis and a hypothetical dinosauroid’.

While part of the article discussed how a life-sized model Stenonychosaurus (presently regarded as a junior synonym of Troodon) was reconstructed and made, the rest was devoted to a thought experiment in which Russell & Séguin (1982) reconstructed a hypothetical ‘evolved’ troodontid that had reached an encephalisation quotient similar to that of humans. Most of us are familiar with the look of the finished product, dubbed the dinosauroid, but some of the decisions Russell & Séguin made in creating the creature have not been mentioned or discussed outside of their paper [adjacent Greg Paul painting, showing a group of troodontids, borrowed from here].

They reasoned that an enlarged brain would result in a shortened facial region, and they used the cranial proportions of a chick embryo as a guide. Based on the idea that troodontids had a reduced dentition compared to other theropods, and on the notion that big-brained primates have a reduced dentition compared to smaller-brained forms, they made the dinosauroid toothless. They further argued that a big-brained head would need to be supported directly over the body, and that a short neck and vertical human-like posture would evolve. The vertical posture meant goodbye to the tail (reduced to a stump in the dinosauroid), and the need to give birth to big-headed babies led them to imagine a broad, human-like pelvis. Dinosauroids were imagined to be viviparous, so the model is equipped with a navel. Because human legs obviously work well for humans, Russell & Séguin proposed that human-like legs would also work for a human-like dinosauroid, and they gave the creature plantigrade feet. Interestingly, they used tree kangaroos as a model, and the feet of the dinosauroid are not tridactyl and clawed as usually shown in drawings, but four-toed, with nails rather than claws, and with the two medial toes smaller than the lateral ones.

All in all, the dinosauroid is disturbingly human-like and, I think, too human-like. While Russell & Séguin made efforts to justify their chain of logic, they may as well have looked at life restorations of hominids, and just ‘reptilised’ them a bit. Essentially the message is that the human body plan is the ‘best’ body plan for a big-brained tetrapod. But Russell & Séguin knew that they would be accused of this, and they ended their discussion by wondering if they had been directed by bias, or if the humanoid shape really would crop up convergently, as do so many other body shapes. Are they wrong, and would things have been different? Well, the last line of their article is: ‘We invite our colleagues to identify alternate solutions’ (p. 36).

Understandably, the unveiling of the dinosauroid model in 1981 resulted in a huge media furore, with Dale Russell in the middle. Some people liked it, others hated it. Today it seems well-known, but I don’t think many people really understand what the point of it was. This isn’t helped by the fact that tabloid newspapers have often used images of it in stories about reptilian aliens or lizard-men, or whatever. Most amusing are those cases where the dinosauroid was completely misunderstood, as is the case in the obscure little book Dinosaur Mysteries (O’Neill 1989). Accompanying some illustrations of Dale Russell, and both Russell and Séguin’s troodontid and dinosauroid models, O’Neill’s text stated…

In 1969, a scientist named Dale Russell found some bones of a small, meat-eating dinosaur called Stenonychosaurus … This dinosaur’s skull showed that it had been small, but with a large skull. The skull also showed that Stenonychosaurus’s eyesight worked like ours. Stenonychosaurus also had hands that resembled humans’. It had thumbs that could be turned inwards to grasp things. This is unusual among animals.

Russell put together a startling model of Stenonychosaurus. He showed it standing upright, like a human. The model was 1.2 (4 ft) tall and weighed about 40 kilograms (90 lb). Russell called this human-like model a “dinosauroid”. People were amazed by this dinosaur which seemed so advanced for its time (p. 24).

I told all of this to Adrienne Mayor while she was researching the dinosauroid for inclusion in her The First Fossil Hunters (2000). She regarded the dinosauroid as an interesting palaeontological fiction echoing the tritons and satyrs made in ancient Greece, and noted that (like tritons and satyrs), the dinosauroid is deemed realistic enough by some for it to be misidentified as real, hence O’Neill’s mistake.

The reactions that palaeontologists have had to the dinosauroid have been mixed. Some have been fairly positive about it. David Norman (1985) considered the dinosauroid in a favourable light, concluding that ‘Such an idea is an obviously fanciful, though provocative thought’ (p. 55). On the same page, an illustration of the dinosauroid by John Sibbick (which looks a bit scarier than the Russell and Séguin model, and also differs from it in foot anatomy) is accompanied by a caption that is even more favourable. After listing the morphological changes required to turn a Cretaceous troodontid into a dinosauroid, it ends by stating that ‘given the right conditions, such changes would be quite feasible’. ‘Feasible’? Note that the captions in the book were not written by Norman, so he shouldn’t get the blame for that (I will refrain from saying who did write the captions).

Another of David Norman’s books, the 1991 Dinosaur!, discusses the use of a real, live dinosauroid in the Granada television TV series that the book was written to accompany (Norman 1991). Played by a person in a suit (obviously), the dinosauroid from Dinosaur! had a more reptilian look to it than Russell and Séguin’s model: it had far scalier-looking skin, snake-like ventral scales, and a vivid green and red colour scheme. The series concluded with the dinosauroid acting as narrator. Another positive interpretation of the dinosauroid came from Cristiano Dal Sasso (2004) in his Dinosaurs of Italy. He seems to have accepted Russell & Séguin’s idea as if it were universally agreed as likely, which it isn’t.

Other palaeontologists have been negative however. At least one reviewer of Russell & Séguin’s paper wrote that ‘I do not see much value in the extremely speculative ‘dinosauroid’ discussion’ (Russell 1987, p. 127). In Predatory Dinosaurs of the World, Greg Paul (1988) found the dinosauroid to be ‘suspiciously human’, and he argued that – were theropods to evolve big brains and ‘intelligence’ – we should instead expect them to retain horizontal bodies and long tails. Theropod expert Tom Holtz has stated much the same, and so far as I can tell from discussion, most dinosaur workers feel this way too. There really isn’t any reason to think that big-brained dinosaurs would have evolved in the first place (recall that even ‘big-brained’ Troodon was, at best, on par with ostriches and opossums), and even if they had, there is also no reason to think that they would have ended up looking like scaly people (or feathery people, given that we now know that troodontids were feathered).

The reason that we humans have the body shape that we do is not – I think – because it’s the ‘best’ body shape for a smart, big-brained biped to have, it is instead the result of our specific lineage’s evolutionary history. Given that, so far as we know, the humanoid body shape has evolved just once, we simply have no way of knowing whether it’s a particularly ‘good’ morphology or not. Furthermore, the humanoid body shape is not a prerequisite for the evolution of big brains given that brains proportionally as big as, or bigger than, those of hominids are found in some birds and fish (that's right: humans do NOT have the proportionally biggest brains).

With this in mind, my feeling on dinosauroids and intelligent theropods and so on is that – if they were to evolve – they wouldn’t look like scaly, or feathery, people, but would instead be far more normal from the theropod point of view. A horizontal body posture, not a vertical one. Digitigrade feet, not plantigrade ones. A long tail, not a reduced one. The main theme here might be familiar to regular blog readers given that I’ve covered much of this before in a post on ground hornbills. While they aren’t particularly big-brained, ground hornbills can be regarded as avian pseudo-hominids, their evolution paralleling our own in several respects. The concluding paragraph of my ground hornbill post was…

No, post-Cretaceous maniraptorans wouldn’t end up looking like scaly tridactyl plantigrade humanoids with erect tailless bodies. They would be decked out with feathers and brightly coloured skin ornaments; have nice normal horizontal bodies and digitigrade feet; long, hard, powerful jaws; stride around on the savannah kicking the shit out of little mammals; and in the evenings they would stand together in the trees, booming out a duet of du du du-du, a deep noise that would reverberate for miles around.

And here we come to the whole reason for the appearance of this post. Inspired by what I wrote I guess, the unique Nemo Ramjet has come up with a new dinosauroid, and it is, I am pleased to say, a million miles away from scaly green humanoids. Dubbed Avisapiens saurotheos, it is of clear dinosaurian ancestry, and I like it. Please view a higher-resolution version at Nemo’s site. Thanks Nemo: awesome stuff!

By the way, no I haven’t yet finished on phorusrhacids.

UPDATE (added 9-11-2006): this blog article clearly inspired recent changes that have been made to wikipedia’s Troodon entry. And for some neat news on troodontids do go here.

Refs - -

Mayor, A. 2000. The First Fossil Hunters. Princeton University Press, Princeton.

Norman, D. B. 1985. The Illustrated Encyclopedia of Dinosaurs. Salamander Books, London.

- . 1991. Dinosaur! Boxtree, London.

O’Neill, M. 1989. Dinosaur Mysteries. Hamlyn, London.

Russell, D. A. 1987. Models and paintings of North American dinosaurs. In Czerkas, S. J. & Olson, E. C. (eds) Dinosaurs Past and Present, Volume I. Natural History Museum of Los Angeles County/University of Washington Press (Seattle and Washington), pp. 114-131.

- . & Séguin, R. 1982. Reconstruction of the small Cretaceous theropod Stenonychosaurus inequalis and a hypothetical dinosauroid. Syllogeus 37, 1-43.

More on phorusrhacids: the biggest, the fastest, the mostest out-of-placest

2006-11-01T15:12:00.000Z

In the previous post we looked briefly at phorusrhacid diversity, stopping on the way to look at the discovery and naming of that ‘well known’ species Phorusrhacos longissimus from the Miocene of Argentina. All of this has been inspired by Chiappe & Bertelli’s (2006) description of the immense new specimen BAR 3877-11, an unnamed Miocene phorusrhacine phorusrhacid that represents one of the biggest members of the group: its skull is 71 cm long and the live animal probably stood 3 m tall (life restoration at left).

By comparing BAR 3877-11 with phorusrhacids known from fairly complete skeletons, we can estimate that it was about 10% bigger than the previously largest known phorusrhacids. But its markedly slender tarsometatarsus indicates that it was gracile, and thus almost certainly not as heavy as the far more robust giant aepyornithids (aka elephant birds, restricted to Madagascar bar a few dubious reports from continental Africa and elsewhere) and dromornithids (aka mihirungs, an Australian group argued to be giant waterfowl). These slender legs suggest that BAR 3877-11 was a fast-moving, cursorial predator, and Chiappe & Bertelli state that ‘the long-established correlation between their corpulence and reduced cursorial agility needs to be re-evaluated’. In other words, they imply that previous studies have associated giant size with ponderous locomotion.

This is somewhat misleading however, in that the only reason that some giant phorusrhacids have been thought of as relatively slow-moving is that they belong to that particular robust-limbed subgroup, the Brontornithinae. The biggest brontornithine, Brontornis burmeisteri from the Miocene of Argentina, was also arguably the biggest phorusrhacid prior to the discovery of BAR 3877-11, but its leg bones are immensely wide and stocky for their length, and its tarsometatarsi are between 50 and 60% the length of its tibiotarsi. These features suggest that it was a walking bird, not a runner, and it is on the basis of this that some authors have interpreted brontornithines as scavengers. You’ll know from discussions about tyrannosaurs that a pure scavenging lifestyle is highly unlikely for any flightless tetrapod (for energetic reasons). Sure, they probably did scavenge (you can imagine them trying to scare teratorns, or a group of hyaena-like borhyeanids, away from a carcass), but they probably foraged for live prey of various kinds as well.

Having mentioned teratorns, while they are now known from the Upper Oligocene/Lower Miocene of South America (Olson & Alvarenga 2002), and thus were contemporaneous with brontornithines, the immense teratorn Argentavis is only known from the Late Miocene, and brontornithines are unknown from this time. So, sorry, you shouldn’t imagine Brontornis scrapping with Argentavis. The oldest teratorn, Taubatornis campbelli, is actually from the same unit – the Tremambé Formation – as the brontornithine Physornis brasiliensis. Both lived alongside New World vultures, flamingos, screamers and caviomorph rodents [the adjacent photo, of the brontornithine Paraphysornis, is borrowed from Cais de Gaia's phorusrhacid blog post].

Getting back to Chiappe & Bertelli’s claims about phorusrhacid running speed, highly relevant is a recent study specifically devoted to this issue. Based on limb proportions and limb bone strength, Blanco & Jones (2005) estimated the running speed of the mesembriornithine Mesembriornis, the patagornithine Patagornis, and a giant phorusrhacine specimen from the Pliocene or Pleistocene of Uruguay. This latter bird (significant in being the youngest phorusrhacid from South America) was one of the largest members of the group, with an estimated height of c. 2.5 m. It might be a species of Devincenzia. Patagornis and the giant phorusrhacine were predicted to have running speeds of 14 metres per second (about 50 km/h) while Mesembriornis had a ridiculous predicted running speed of 27 metres per second (about 97 km/h). For comparison, emus run at 14 metres per second, an ostrich reaches perhaps 17 metres per second (about 60 km/h) and cheetahs are reported to reach or exceed 27 metres per second.

Unsurprisingly, Blanco & Jones (2005) doubted if their predictions were accurate and they wondered if the unusual bone strength of some phorusrhacids – Mesembriornis in particular – might be related to something other than running speed. Could it be something to do with kicking? Based on the forces needed to break bones, they showed that Mesembriornis would be able to produce a force of over 2000 Newtons with its kick: strong enough to fracture bones. Thus it’s possible that some phorusrhacids used kicking as a way of breaking open bones to feed on marrow (how do the brontornithines, with their super-robust limb bones and inferred scavenging habits, fit into this?). It’s also possible that the birds used this kicking power to stun or kill prey, and here you will of course be thinking of the Secretary bird Sagittarius serpentarius, a cursorial raptor (superficially similar to a seriema) that kills or stuns snakes and other terrestrial prey with repeated kicks.

The foot claws of some phorusrhacids also support the idea that they used their feet in maiming or killing as the claws are laterally compressed, curved and sharp-tipped. That’s not necessarily the normal morphology for predatory birds, as many cursorial birds (and non-avian theropods) actually have rather blunt, stout foot claws. Tonni & Tambussi (1988) described the foot morphology of the Miocene psilopterine Psilopterus and showed that its foot claws were nearly identical to those of the living seriema Cariama cristata.

What’s interesting about this is that the second toe claw in Cariama is slightly enlarged relative to those of digits III and IV (as you can see from the very poor accompanying photos). Seriemas reportedly use the claw to aid in tree-climbing, and I’d like to know if they use it in attacking or killing prey. A great many other birds, including raptors and many passerines, have similarly enlarged claws on digit II however. I’ve previously been guilty of comparing this ‘enlarged’ claw with the raised sickle-claw seen in dromaeosaurids and other Cretaceous theropods, but what we have in phorusrhacids and seriemas clearly isn’t as elaborate, so there’s no indication that they used it to slash open the bellies of prey or anything like that (and here I’ll avoid the debate about the function of sickle-claws*). I doubt if even small phorusrhacids climbed trees, so presumably they used the claw in dispatching or manipulating prey.

* A recent study has claimed that sickle-claws could not function as slashing or stabbing weapons, but were perhaps used instead as climbing crampons, enabling dromaeosaurids to climb the bodies of their prey. I feel that there are major flaws in this study and that its conclusions are erroneous (see comments in Naish 2006).

While conventionally regarded as South American birds, there have been occasional reports of phorusrhacids from elsewhere. Two supposed European members of the group, Ameghinornis minor from Eocene-Oligocene France and Aenigmavis sapea from Eocene Germany, were identified in the 1980s (actually, Ameghinornis minor was first described [as Strigogyps minor] in 1839, but its new name and proposed affinity to phorusrhacids weren’t published until 1987). Both were weakly flighted or flightless birds about the size of a partridge.

Given that a few other Eocene European tetrapods have been suggested to be particularly closely related to South American taxa (namely the ratite Palaeotis, the peradectine opossums and the supposed anteater Eurotamandua), Ameghinornis and Aenigmavis were thought to perhaps indicate that phorusrhacids had originated in Europe and later spread (via Africa) to South America (Peters & Storch 1993). However, reanalysis has shown that both names are best regarded as junior synonyms of Strigogyps, and furthermore that Strigogyps differs significantly from phorusrhacids in lacking the derived characters that unite the members of this group (Mayr 2005). We’re not actually sure what Stigogyps is (though its tarsometatarsus is similar in some details to that of a trumpeter), but its re-evaluation strikes phorusrhacids off the list of European fossil taxa. Incidentally, there are unpublished Palaeocene and/or Eocene fragments from England and North America that, inspired by the 1987 identification of Aenigmavis, have also been suggested to be phorusrhacids. They await evaluation but, like Strigogyps, it is doubtful if they really have anything to do with Phorusrhacidae.

I should point out that the other European Eocene forms previously regarded as being of South American affinity have also been reinterpreted. Palaeotis, a small ratite argued by some to be a stem rhea, has more recently been found to be outside of the clade that includes rheas, ostriches, cassowaries and emus. Peradectine opossums may or may not be of South American origin: however, by the Eocene they occurred in North America and Europe and they later occurred in Asia and Africa. They do not seem to provide special evidence for a faunal link between South America and Europe. Finally, the supposed anteater Eurotamandua seems not to be an anteater, nor even a xenarthran, and as such there is nothing South American about it [adjacent image shows, at top, skeleton and life restoration of Eurotamandua, with the Eocene pangolin Eomanis at bottom. Taken from here].

What is almost certainly a non-American phorusrhacid was reported in 1987… from the Eocene of Antarctica (Case et al. 1987). Known only from the anterior part of the premaxillae, the specimen must have belonged to a reasonably large bird, but not much more than that is known about it. Older phorusrhacids are known from the Palaeocene of South America, so the specimen does not demonstrate that phorusrhacids originated in Antarctica: rather, it probably shows that they were common to both continents prior to their separation in the Oligocene.

An interesting parallel is provided by the fossil record of sloths, as while long regarded as of South American origin, the oldest sloth is a Middle Eocene fossil from Seymour Island (Antarctica). From time to time people make the point that some really interesting, major events in tetrapod history must have occurred in ancient Antarctica – if only it wasn’t for that damned ice sheet. Luckily, we’re doing all we can to get rid of it (that’s meant to be ironic). Anyway, we might speculate that Antarctica was home to numerous phorusrhacid lineages prior to its glaciation, but we’ll likely never know about them.

More to come…

Refs - -

Blanco, R. E. & Jones, W. W. 2005. Terror birds on the run: a mechanical model to estimate its maximum running speed. Proceedings of the Royal Society of London B 272, 1769-1773.

Case, J. A., Woodburne, M. O. & Chaney, D. S. 1987. A gigantic phororhacoid(?) [sic] bird from Antarctica. Journal of Paleontology 61, 1280-1284.

Chiappe, L. M. & Bertelli, S. 2006. Skull morphology of giant terror birds. Nature 443, 929.

Mayr, G. 2005. “Old World phorusrhacids” (Aves, Phorusrhacidae): a new look at Strigogyps (“Aenigmavis”) sapea (Peters 1987). PaleoBios 25, 11-16.

Naish, D. 2006. The Carnivorous Dinosaurs [review]. The Palaeontology Newsletter 62, 122-126 [free pdf available here].

Olson, S. L. & Alvarenga, H. M. F. 2002. A new genus of small teratorn from the Middle Tertiary of the Taubaté Basin, Brazil (Aves: Teratornithidae). Proceedings of the Biological Society of Washington 115, 701-705.

Peters, D. S. & Storch, G. 1993. South American relationships of Messel birds and mammals. Kaupia 3, 263-269.

Tonni, E. P. & Tambussi, C. P. 1988. Un nuevo Psilopterinae (Aves: Ralliformes) del Mioceno tardio de la Provincia de Buenos Aires, Republica Argentina. Ameghiniana 25, 155-160.

Terror birds

2006-10-27T23:11:00.001+01:00

Were you to visit sunny Texas 5 million years ago (cough cough), a giant predatory bird, 3 m tall with a head 70 cm long, might have kicked you down and eviscerated you with its immense hooked bill. I am of course talking about phorusrhacids, sometimes called terror birds, the mostly large, flightless predatory birds of the prehistoric Americas and elsewhere, and as you’ll know if you’ve been keeping an eye on the news, a new and exciting member of the group was described last week in Nature (Chiappe & Bertelli 2006). I like to promote the idea that big eagles are awesome powerful predators, well able to tackle and kill surprisingly big mammals (see When eagles go bad and The biggest eagle, part I) but, needless to say, even big eagles pale into near-insignificance next to these distant cousins.

Yet again, it’s funny how things work out. My life right now mostly consists of job-hunting, but because of the various part-time teaching jobs I have I am always working on powerpoint presentations. Last week I put the finishing touches to ‘The evolution of birds in the Cenozoic’, and of course I added a section on phorusrhacids. Now that Chiappe & Bertelli (2006) has been published I will have to make a few changes.

I’ve always been very interested in phorusrhacids and, unlike many of the animals I write about (the shame), I have some experience with them. What are they? They are universally agreed to be relatives of the living seriemas (Cariamidae), but differ from them in having a far more robust bill and jaws, smaller bony processes on the humerus, and a narrower pelvis. They also, of course, grew to a much larger size. The two living seriema species are South American, but members of similar, closely related groups (the bathornithids and idiornithids) inhabited North America from the Eocene to the Miocene and Europe from the Eocene to the Oligocene. I have a lot more to say on the affinities of all of these birds: you’ll have to wait for a future post (Giant hoatzins of doom: the ‘South American land bird’ theory).

The various phorusrhacid genera and species have been reviewed twice in the past 50 years. Patterson & Kraglievich (1960) looked at the Pliocene species and mostly discussed the relatively obscure taxa Hermosiornis and Onactornis (the latter is currently regarded as synonymous with Devincenzia). Perhaps because their study was written in Spanish [with only a brief English summary], it has been widely overlooked. It also has far too few illustrations and – to quote Storrs Olson (1985)* – is ‘a nightmare of typographical errors’ (p. 145). Apparently it was meant to be just the preliminary nomenclatural part of a much larger revision of the whole group by Bryan Patterson, but this never appeared. Fortunately, Alvarenga & Höfling (2003) looked at phorusrhacids anew and reviewed all the taxa, providing information on historical taxonomy, palaeoecology, and phylogenetic affinities. While they didn’t perform a cladistic analysis, this is pretty much the sort of study we have long needed, and the fact that it is widely and freely available on the web as a pdf (go here) means that it will enjoy widespread consultation (if only all publishers did this with academic papers: remember, the availability of pdfs is never under the control of authors). For now, it is the ‘standard work’ on the group.

* More than any other person in zoological writing, Olson has produced an impressive list of scathing quotes and insults. One day I’ll make a point of collecting them all together.

Alvarenga & Höfling (2003) grouped phorusrhacids into five subgroups; the small, gracile psilopterines, known from the Palaeocene to the Pliocene and including the oldest of all phorusrhacids; the mid-sized, shallow-skulled, gracile-legged mesembriornithines of the Miocene-Pliocene; the mid-sized patagornithines of the Oligocene, Miocene and Pliocene; the gigantic, robust brontornithines of the Oligocene and Miocene; and the mostly large, gracile-legged phorusrhacines of the Miocene, Pliocene and Pleistocene. The last group was the only one to make it into the Pleistocene, and the only group to invade North America. The smallest psilopterine was about 70 cm tall while the biggest brontornithines and phorusrhacines were about 3 m tall and among the biggest birds of all time. Mesembriornithines were, proportionally, about as long-legged as emus or rheas, while brontornithines included the most stocky-legged birds of them all.

It is of minor frustration that the phorusrhacids we hear about the most are among the most poorly known. The ‘best known’ phorusrhacid, the one featured in every single prehistoric animal book, is Phorusrhacos longissimus from the Miocene of Argentina. But it’s only ‘best known’ because it was the first member of the group to be named, and compared to a number of far more obscure species, it is poorly known and mysterious. Of its skull, for example, we only have the lower jaw and some fragments of cranium. Florentino Ameghino (1854-1911), the famous Argentine zoologist/palaeontologist who discovered and named it and several other phorusrhacids, did write in 1895 of seeing a complete skull, encased in rock in the field, but he was only able to sketch it and recover fragments. His drawing is of a complete, pristine skull and it is on the basis of this that an entire replica skull has been produced (see accompanying image). Compare this with the patagornithines Patagornis and Andalgalornis, for example, both of which are known from awesome, complete skulls with good, associated, near-complete skeletons.

Incidentally, you might have seen the name Phorusrhacos written as Phororhacos (and Phorusrhacidae written as Phororhacidae). The former is the older, and thus correct, spelling, coined by Ameghino in 1887. At this time Ameghino thought that he had discovered a new herbivorous toothless mammal, perhaps a sloth, and Phorusrhacos was named to mean something like ‘branch holder’. It’s also a switched-round version of Rhacophorus, a genus of arboreal Asian frogs: that name also meaning ‘branch holder’. This isn’t a coincidence – Ameghino did this sort of thing with lots of names. When in 1889 Ameghino discovered that Phorusrhacos was really a bird, he changed the name to Phororhacos, as this (apparently) means something like ‘rag bearer’ and Ameghino regarded this as more appropriate etymologically than ‘branch holder’ (I regret that I have no idea why, however). Changing of names like this is not allowed under the guidelines of the ICZN and hence Phororhacos – still used by some people even today – should be suppressed. An ICZN ruling of 1992 made Phorusrhacos and Phorusrhacidae the officially accepted spellings.

Speaking of Phorusrhacos, the painting at top - depicting this taxon - is one of the most famous phorusrhacid renditions ever (it's borrowed from the Burian gallery), and was produced by one of the 20th century's greatest palaeo-artists, Zdenek Burian (1905-1981). The colour scheme used in the painting has been widely copied by other artists: for a discussion on this subject go here.

The new phorusrhacid described by Chiappe & Bertelli (2006) consists only of a skull and some leg bones (other elements might be known, but aren’t mentioned), but is significant for its size and the completeness of the skull. Discovered in Miocene rocks of Comallo, Argentina, it appears to be a phorusrhacine closely related to Devincenzia, another of those obscure taxa known from pretty good remains. For reasons that I don’t quite grasp, the new specimen isn’t named (whether it represents a new taxon that will be named elsewhere, or whether it proves referable to an already-named form [like Devincenzia] is not stated) and currently only has the accession number BAR 3877-11 (BAR = Museo Asociación Paleontológico Bariloche, Argentina). Anyway, with a total length of 71 cm, BAR 3877-11 possesses the largest avian skull. What is slightly odd about Chiappe & Bertelli’s paper is that they continually refer to giant phorusrhacids as the ‘largest birds known’. While it is certainly true that some of these birds – reaching a total height of about 3 m and a weight of 350 kg or more – were immense, they were similar in size to, and perhaps smaller than, the biggest aepyornithids and dromornithids, so this isn’t clear cut.

And I have to stop there. More on phorusrhacids in the next post, looking at brontornithine lifestyle, mesembriornithine running speed (were they the fastest-running birds ever?), and the anatomy of feet and skulls [available here].

PS - I intended to add more images to this post, but I’m having trouble in getting blogger to upload them. For the latest news on Tetrapod Zoology do go here.

Refs - -

Alvarenga, H. M. F. & Höfling, E. 2003. Systematic revision of the Phorusrhacidae (Aves: Ralliformes). Papéis Avulsos de Zoologia, Museu de Zoologia da Universidade de São Paulo 43, 55-91.

Chiappe, L. M. & Bertelli, S. 2006. Skull morphology of giant terror birds. Nature 443, 929.

Olson, S. L. 1985. The fossil record of birds. In Avian Biology, Volume III, pp. 79-238.

Patterson, B. & Kraglievich, J. L. 1960. Sistematica y nomenclatura de las aves fororracoideas del Plioceno Argentino. Publicaciones del Museo Municipal de Ciencias Naturales y Tradicional de Mar del Plata 1, 1-52.

Lunging is expensive, jaws can be noisy, and what’s with the asymmetry? Rorquals part III

2006-10-25T00:54:00.000+01:00

In the previous post I discussed the basic anatomy and behaviour involved in lunge-feeding, a style of predation practiced by rorquals, the biggest, fastest and most dynamic of baleen-bearing cetaceans. By engulfing literally tons of water within a unique, flexible buccal pouch, rorquals change shape from ‘a cigar shape to the shape of an elongated, bloated tadpole’ (Orton & Brodie 1987, p. 2898). Their feeding style is anything but passive: Paul Brodie, an expert on rorqual feeding, has described it as ‘the largest biomechanical action in the animal kingdom’. After discussing rorquals with whale expert Nicholas Pyenson, my good friend Matt Wedel, in one of several blog posts on rorquals and other mysticetes (that’s three separate links there), provided the most excellent quote…

The big baleen whales pick their targets and engulf them with their giant jaws and extensible mouth/throat region. They are often feeding on swarms of krill that measure kilometers in extent. Rather than think of big whales as filter feeders, we should think of them as predators that take bites off of superorganisms that are hundreds of times larger. The fact that the krill are strained out of the water by the baleen is a matter of processing - it comes after the whale has taken a bite.

That’s great: I’ll be stealing it for use in lectures. The photo at top features the immense jaws of an Antarctic blue whale, kept at Washington D.C.’s Garber Facility (part of the National Museum of Natural History), and is borrowed from here on Matt's blog site.

Recent studies show that lunge-feeding is not just dynamic, it is also extremely expensive in metabolic terms, and even though rorquals glide as they lunge (thereby conserving some energy), it still seems that lunge-feeding is so energetically costly that constraints are imposed on rorqual behaviour. Theoretically, large-bodied species store more oxygen thanks to their size, and therefore have a higher theoretical aerobic dive limit (TADL). Indeed in marine mammals as a whole there is a trend of increasing dive depth and duration with increasing body size. If we look at the largest rorquals – the blue and fin – we find TADLs of 31.2 and 28.6 minutes. Yet the actual aerobic dive limits of the two species are respectively 7.8 and 6.3 minutes (Croll et al. 2001). For comparison, right whales – which weigh about half as much as blue whales – spend about twice as long foraging under water as blue whales. To quote Acevedo-Gutiérrez et al. (2002) ‘the largest predators on earth have the shortest dive durations relative to their TADL’ (p. 1747). Note also that rorquals don’t dive deep for their size: fin whales have been reported to dive down to 470 m, but that’s not deep for such a big animal (total length 18-25 m), nor were the dives in question long in duration at less than 13 minutes [adjacent photo, from the Right Whale Aerial Surveys site, shows a feeding Fin whale].

Goldbogen et al. (2006) studied the kinematics of diving and lunge-feeding fin whales and showed that the rapid acceleration attained during lunge-feeding is immediately met by a relatively larger deceleration, presumably caused by the opening of the buccal pouch. The whales also rolled their bodies during lunging and may in fact spin about their long axis during feeding events, and at the bottom of a feeding dive a whale undertook a series of vertical excursions. It seems that the rapid acceleration and deceleration, and the dynamic movement, involved in lunge-feeding is highly costly, forcing rorquals to limit their dive time, and to increase the time that they need to spend at the surface recovering (Acevedo-Gutiérrez et al. 2002).

Some very interesting implications result from this expensive feeding style. Because lunge-feeding is so costly, it is likely only profitable where prey concentrations are high. Lunge-feeding rorquals cannot make a living anywhere there is suitable prey, therefore, but are ecologically tied to productive regions such as submarine canyons and the Southern Boundary of the Antarctic Circumpolar Current. A blue whale has been estimated to require one metric ton of krill per day.

When this is combined with the fact that some of the prey that rorquals depend upon, such as krill, are declining, it becomes clear why certain rorqual populations are struggling to recover from the days of commercial whaling. Indeed work on African hunting dogs Lycaon pictus has shown that high metabolic costs incurred during predation cause some species to be competitively inferior to others, forcing their populations to remain at low levels (Gorman et al. 1998). So lunge-feeding is a high-maintenance activity, and we should not be surprised that lunge-feeding rorquals that lunge-feed only on specific prey species are endangered, and liable to decline.

Here it’s worth noting that different rorqual species specialize on different prey, though some (the minkes and the fin whale) seem to be opportunists. Sei whales specialize on crustaceans, in particular on copepods, and blue whales are specialist krill predators (Sigurjónsson 1995). Furthermore, not all rorqual species feed by lunging – the sei in particular uses a technique called skimming, whereby the whale keeps its mouth slightly open and moves forward through a body of prey at a continuous speed. It would be interesting to know how the morphology, kinematics and energetics of the sei compare to those of lunge-feeding rorquals, but so far as I know these issues remain largely unstudied. We do know that its baleen is particularly fine, allowing it to filter the comparatively small copepods [adjacent photo, also from the Right Whale Aerial Surveys site, shows a feeding sei. It’s feeding on its side. Hmm].

Thanks to the work of August Pivorunas, Paul Brodie and colleagues, the engulfing mechanism of rorquals has been reasonably well understood since the 1970s. However, questions always remained. How is it that, during lunge feeding, agile, highly reactive prey remain within the mouth cavity prior to the mouth’s closure? Man-made devices of similar size are incapable of retaining prey without them escaping prior to the devices’ closure (Brodie 1978). When a rorqual carcass is processed at a whaling station, the soft tissue of the throat is removed by flensing. Using cables and straps, the jaws are then winched open, and the tendons and muscles holding the mandibles in place are then cut, freeing the jaw from the skull. Because the jaw is winched open without the very heavy throat tissue attached, its movement during the procedure approximates the natural movement of the jaw when the animal is alive and underwater. As the jaw is winched open ‘a familiar sequence of sounds was observed to originate from the jaw apparatus … a growl or rumble, a low hydraulic suction noise, following by a powerful knock, the latter seeming to emanate from the tip of the jaw’ (Brodie 1993, p. 546). The noise reverberated throughout the jaw, making the entire structure vibrate. Unusual loud noises have been reported from live, feeding fin whales, so what Brodie reported apparently occurs in live whales, and not just dead ones.

What might cause these noises? Could it be that the articular condyles of the jaw bones were grinding against the bones of the skull? Well, no, as large masses of collagen and lipid are sandwiched between the lower jaw and skull, and in the specimens Brodie examined there was no suggestion that this tissue had been compromised. Could it be that the jaw tips were grinding together? Again, no, as soft tissue separates the jaw tips and, anyway, the jaw tips were being forced apart when the noises were being made, not together. Brodie (1993) concluded that the noise was a consequence of the stretching apart of a synovial capsule located between the jaw tips. And, funnily enough, here we have something that is of direct relevance to all of us (well, most of us. Well, those of us who have heard our joints make crack noises).

As synovial capsules are forced apart, a partial vacuum forms in the joint cavity. Adjacent water vapour and blood gases from surrounding tissues rush to fill the vacuum, and as it collapses a noise results. Such noises range from low rumbles to loud knocks. This process is termed pseudocavitation (to distinguish it from cavitation: the process whereby the medium actually ruptures), and I’ve just realized that this solves one of the greatest mysteries in all of biomechanics: why our knuckles crack. I can’t tell you how many times I’ve sat around with colleagues, pondering this very question.

If the lower jaws of fin whales really do make a loud bang or crack when they are opened to full gape, we can speculate that the whales might use this to help them retain prey within the mouth during engulfment. Captured prey would be startled away from the jaw edges by the noises, and this isn’t unlikely given that we’ve long known that rorquals exploit the behavioural traits of their prey to concentrate them during predation (it is well known that humpbacks use bubbles to encircle prey, and in fact fin and Bryde’s whales have been reported doing this too). To my knowledge, the ‘noisy jaw’ hypothesis has only been proposed for fin whales. Is it unique to this species, or practiced more widely?

And speaking of fin whales…. generally speaking, tetrapods have symmetrical bodies and symmetrical arrangements of pigmentation. Why then are fin whales asymmetrical? Mostly dark on the left side of the head (this goes for the baleen and the left side of the tongue), they are mostly light on the right side (and, again, this goes for the baleen and the right side of the tongue). While individuals belonging to various species will sometimes exhibit asymmetrical pigmentation (and rorquals, such as minkes and sei whales, are among them), fin whales are consistently like this: all of them.

Does this serve a function? Mostly it has been thought that it is something to do with counter-shading: if the whale swims anti-clockwise around its prey it might be camouflaged against the water and hence invisible, or is it that it swims clockwise around its prey, frightening them with its vivid whiteness and causing them to bunch up? Both ideas have been proposed (Ellis 1982). Most recently, cetologists seem to have favoured the idea that fin whales actually swim on their right side while lunge-feeding, thereby using a sort of rotated counter-shading. I’ve seen photos that apparently support this idea of right-sidedness, but I don’t know if there any good studies on the subject. There is widespread evidence for handedness across Tetrapoda (including in whales), so does this mean that all fin whales are right-handed, or left-handed?

That’s it on rorquals for now, though I plan at some stage to talk about the recently resurrected and recently discovered taxa, such as the Pygmy blue whale, Antarctic minke and Omura’s whale. And what is it with the name Balaenoptera musculus?

One last thing. I can’t go without relating the amazing tale of how I personally encountered Brodie’s 1993 paper ‘Noise generated by the jaw actions of feeding fin whales’. While collecting papers at Southampton University’s Boldrewood Biomedical Science Library one day, I decided to find and photocopy this paper. All I knew was that it had been published in Canadian Journal of Zoology. I had no idea what volume it had been published in, nor in what year it had been published. The problem is that the Boldrewood library has a near-complete run of Canadian Journal of Zoology, with many metres of shelving being taken up by volume after volume after volume. In a futile effort to begin my search, I pulled out a single volume, at random, and opened it, at random. I had found the paper. Ha – and people tell me I’m not psychic! :)

For the latest news on Tetrapod Zoology do go here.

Refs - -

Acevedo-Gutiérrez, A., Croll, D. A. & Tershy, B. R. 2002. High feeding costs limit dive time in the largest whales. The Journal of Experimental Biology 205, 1747-1753.

Brodie, P. F. 1978. Alternative sampling device for aquatic organisms. Journal of the Fisheries Research Board of Canada 35, 901-902.

- . 1993. Noise generated by the jaw actions of feeding fin whales. Canadian Journal of Zoology 71, 2546-2550.

Croll, D. A., Acevedo-Gutierrez, A., & Tershy, B. R. & Urbán-Ramírez, J. 2001. The diving behavior of blue and fin whales: is dive duration shorter than expected based on oxygen stores? Comparative Biochemistry and Physiology 129A, 797-809.

Ellis, R. 1982. The Book of Whales. Alfred Knopf, New York.

Goldbogen, J. A., Calambokidis, J., Shadwick, R. E., Oleson, E. M., McDonald, M. A. & Hildebrand, J. A. 2006. Kinematics of foraging dives and lunge-feeding in fin whales. The Journal of Experimental Biology 209, 1231-1244.

Gorman, M. L., Mills, M. G., Raath, J. P. & Speakman, J. R. 1998. High hunting costs make African wild dogs vulnerable to kleptoparasitism by hyaenas. Nature 391, 479-481.

Orton, L. S. & Brodie, P. F. 1987. Engulfing mechanisms of fin whales. Canadian Journal of Zoology 65, 2898-2907.

Sigurjónsson, J. 1995. On the life history and autecology of North Atlantic rorquals. In Blix, A. S., Walløe, L. & Ulltang, Ø. (eds) Whales, Seals, Fish and Man. Elsevier Science, pp. 425-441.

From cigar to elongated, bloated tadpole: rorquals part II

2006-10-24T12:05:00.000+01:00

More on rorquals (for part I go here), this time looking at the basics of their morphology and feeding behaviour. The rostrum in rorquals is long and tapers to a point (though it is comparatively broad in blue whales) and, in contrast to other mysticetes, a stout finger-like extension of the maxillary bone extends posteriorly, overlapping the nasals and abutting the supraoccipital (the shield-like plate that forms the rear margin of the skull). The dorsal surfaces of the frontals (on the top of the skull) possess large depressions while the ventral surfaces of the zygomatic processes (the structures that project laterally from the cheek regions) are strongly concave, again unlike the condition in other mysticetes.

Rorqual lower jaws are immense, beam-like bones that bow outwards along their length. The symphyseal area (the region where the jaw tips meet) is unfused, as is the case in all mysticetes (even the most basal ones) but not other cetaceans, meaning that the two halves of the jaw can stretch apart at their tips somewhat. Exceeding 7 m in blue whales, rorqual lower jaws are the largest single bones in history (ha! Take that Sauropoda).

A section of blue whale jaw was once ‘discovered’ at Loch Ness and misidentified as the femur of an immense, hitherto undiscovered tetrapod. Occasionally rorqual skulls have been discovered in which the long lower jaws have been stuck wedged inside various of the skull openings and with their tips protruding like tusks. People unfamiliar with cetacean skulls have then naively assumed that the skull belonged to some sort of tusked prehistoric sea monster. Ben Roesch discussed cases of this (go here), and also noted the case of the Ataka carcass of 1956: a giant beached animal possessing divergent ‘tusks’ that are in fact the separated halves of a rorqual’s lower jaw (see adjacent image).

I’ve come across another case of this sort of thing. The accompanying newspaper piece, from The Telegraph of June 29th 1908, features a skull trawled up by the Aberdeen vessel Balmedie (sailing out of Grimsby), and thought by the article’s writer to be that of ‘some prehistoric monster’, apparently with tongue preserved. It’s clearly a rorqual skull, and the pointed, narrow rostrum and posterior widening of the mesorostral gutter indicates that it’s a minke whale skull.

Moving back to the morphology of the rorqual lower jaw, a tall, well-developed coronoid process – way larger than that of any other mysticete – projects from each jaw bone and forms the attachment site for a tendinous part of the temporalis muscle, termed the frontomandibular stay.

All of these unusual features are linked to the remarkable feeding style used by rorquals. How do they feed? Predominantly by lunge-feeding (also known as engulfment feeding): by opening their mouths to full gape (c. 45º), and then lunging into a mass of prey. Those depressed areas on the frontals and zygomatic processes have apparently evolved to allow particularly large temporalis and masseter muscles, the muscles involved in closing the jaw. The frontomandibular stay provides a strong mechanical linkage between the lower jaw and skull and seems primarily to amplify the mechanical advantage of the temporalis muscles.

As a rorqual lunge-feeds, an immense quantity of water (hopefully containing prey) is engulfed within the buccal pouch, transforming the whale from ‘a cigar shape to the shape of an elongated, bloated tadpole’ (Orton & Brodie 1987, p. 2898). While a rorqual uses its muscles to open its jaws, the energy that powers the expansion of the buccal pouch is essentially provided by the whale’s forward motion, and not by the jaw muscles. In other words, the engulfing process is powered solely by the speed of swimming. Orton & Brodie (1987) noted that the engulfed water ‘is not displaced forward or moved backward by internal suction, but is simply enveloped with highly compliant material’ (p. 2905). Rorquals do not, therefore, set up a bow wave as they engulf.

A rorqual may engulf nearly 70% of its total body weight in water and prey during this action, which in an adult blue whale amounts to about 70 tons (Pivorunas 1979). In order to cope with this, the tissues of the buccal pouch must be highly extensible and able to cope with massive distortion. The ventral surface of the pouch is covered by grooved blubber, on which the 50-90 grooves extend from the jaw tips to as far posteriorly as the umbilicus. The ventral grooves can be extended to 4 times their resting width, and to 1.5 times their resting length. Internal to the grooved blubber is the muscle tissue of the buccal pouch, and this is unique, containing large amounts of elastin, and consisting of an inner layer of longitudinally arranged muscle bands and an outer layer where the bands are obliquely oriented (Pivorunas 1977).

When a rorqual lunges, delicate timing is needed, otherwise the buccal pouch will rapidly fill with seawater and not with prey. How then do rorquals get their timing just right? It seems that rorquals possess batteries of sensory organs within and around the buccal pouch: there are laminated corpuscles closely associated with the ventral grooves that might serve a sensory function, and located around the edges of the jaws, and at their tips, are a number of short (12.5 mm) vibrissae. Long assumed to be vestiges from the time when whale ancestors had body hair, it now seems that these structures have a role in sensing vibrations.

Once a mass of prey is engulfed, a rorqual then has to squeeze the water out through its baleen plates while at the same time retaining the prey. Rorqual baleen plates number between 219 to 475 in each side of the jaw (the number of plates is highly variable within species, with sei whales alone having between 219 to 402), and each plate ranges in length from 20 cm (in the minkes) to 1 m (in the blue). As the whale stops lunging forward, the pressure drops off, allowing deflation of the buccal pouch. Passive contraction of the blubber grooves and active contraction of the muscle layer within the buccal pouch also occurs at this time.

For an outstanding sequence of photos illustrating engulfment in action, see Randy Morse’s photos of a feeding blue whale here.

So that’s the basics. But there’s so much more to the subject than this. How is it that, during lunge feeding, agile, highly reactive prey remain within the mouth cavity prior to the mouth’s closure? Why do some rorquals make loud noises during lunge-feeding? Why, given their immense size and theoretical high aerobic dive limit, do big rorquals not spend more time lunge-feeding beneath the surface? Why do some rorquals exhibit strongly asymmetrical patterns of pigmentation? And don’t forget that not all rorquals lunge-feed. More on these issues in the following post.

The painting at top is from Valter Fogato's site.

For the latest news on Tetrapod Zoology do go here.

Refs - -

Orton, L. S. & Brodie, P. F. 1987. Engulfing mechanisms of fin whales. Canadian Journal of Zoology 65, 2898-2907.

Pivorunas, A. 1977. The fibrocartilage skeleton and related structures of the ventral pouch of balaenopterid whales. Journal of Morphology 151, 299-314.

- . 1979. The feeding mechanisms of baleen whales. American Scientist 67, 432-440.

A 6 ton model, and a baby that puts on 90 kg a day: rorquals part I

2006-10-23T23:45:00.001+01:00

I’ve said it before but it’s worth saying again: everyone interested in animals is, I assume, fascinated by whales. All secondarily aquatic tetrapods are neat, but here we have a group that has evolved giant size, suspension feeding, macropredation, deep-diving and echolocation, among other things. Right now, I have rorquals on my mind, and I’m not quite sure why: I haven’t been doing any research on them lately, nor have they been in the news or anything*. However, later this week my family and I are visiting the Natural History Museum (London) and I’m particularly looking forward to showing Will (who’s 5) the life-sized Blue whale Balaenoptera musculus model that hangs in the Mammal Hall (the room formerly known as the Whale Hall). I’m so interested in this model that I feel it worthy of a short digression.

* Bar the news that Iceland is resuming low-level whaling. Yay Iceland.

Late in the 1920s plans to replace the old whale hall of the British Museum (Natural History) were fulfilled. The new, steel-girdled hall finally allowed the 1934 display of the Blue whale skeleton [image above, from here] that had been kept in storage for 42 years due to lack of space. Measuring 25 m in length, the animal had stranded at Wexford Bay, SE Ireland, in 1891. It – as in, the skeleton alone – weighs over 10 tons. But some people at the museum wanted more, and in 1937 taxidermist Percy Stammwitz (1881-1954) made the bold suggestion that a life-sized model of a Blue whale could be constructed within the Whale Hall itself. Later that year Stammwitz and his son, Stuart, began work on the project, their technical advisor being cetologist Francis C. Fraser (1903-1978).

Scaling up from a clay model, a wooden frame was constructed, and this was then covered in wire mesh and plaster. A trapdoor on the stomach was constructed for (I presume) internal maintenance, though apparently the workmen would sneak inside the model for secret smoking. On several occasions I’ve heard rumours that a time capsule was left inside this trapdoor before it was sealed: Stearn (1981) made no mention of this specifically, but did write that a telephone directory and some coins were left inside (p. 132). The completed model weighed between 6 and 7 tons and, when the time came for the whale to be painted, Stammwitz and Fraser disagreed, eventually choosing bluish steel-grey. Completed in December 1938, it was the largest whale model ever constructed though larger models, constructed from the same design templates, have since been produced by several American museums [adjacent image from here].

What are rorquals? They are the eight or so Balaenoptera species of the mysticete family Balaenopteridae*, all of which open their jaws wide to engulf masses of prey and possess a highly distensible throat pouch and extensible longitudinal grooves on the throat and belly. They occur in seas worldwide and range from 6 to 30 m in length. The only other living balaenopterid** is the Humpback Megaptera novaeangliae, and it is generally regarded as the sister-taxon to the rorquals. I’ve seen two explanations for the term rorqual. The commonest is that it derives from the Norwegian rørhval and means ‘grooved whale’ – a reference to those longitudinal grooves. The less common explanation is that it originated from the French for ‘red throat’, this supposedly being a reference to the reddish colour visible between the throat grooves when the whale’s buccal pouch is extended (Berta & Sumich 1990).

* Most books on whales state that there are five rorqual species. As with so many tetrapod groups, the number of recognised species has increased in recent years, both as ‘old’ species have been resurrected from synonymy (Antarctic minke B. bonaerensis and Pygmy bryde’s B. edeni), and as new species have been described (Omura’s whale B. omurai).

** Some workers have included the Grey whale Eschrichtius robustus within Balaenopteridae. It is mostly agreed, however, that Eschrichtius belongs to a small clade (Eschrichtiidae) best regarded as the sister-taxon to Balaenopteridae.

Rorquals grow fast, reaching sexual maturity at between 5 and 12 years of age in the larger species. They can produce up to 1.5 calves per 2-year period, though three years between calves is probably more normal. Pregnant females increase their weight by 26% and, thanks to lipids stored in their visceral fat and blubber, increase their total energy budget by a staggering 80% (Víkingsson 1995). After a pregnancy of 10-13 months, babies are suckled for 4-10 months and (in blue whales) are provided with 200 litres of milk a day. Unsurprisingly, babies increase their weight substantially during this time, with a 2-3 ton newborn blue whale putting on 90 kg a day, and reaching 20 tons by the time it is weaned. They are the fastest growing baby mammals. Rorquals are long-lived, with minkes B. acutorostrata reaching their forth or fifth decades, Sei B. borealis surviving to 65 or so, and Fins B. physalus to 85 or 90, or possibly 100. Incidentally, right whales (balaenids) are thought to survive into their second century, but they’re not rorquals.

We all know that rorquals are big, that they possess baleen, and that they feed by engulfing crustaceans, small fish and other prey. They spend summer in the polar regions, where they feed and put on weight, and then they migrate in the winter to the tropics, where they breed and give birth to their enormous calves… but they don’t _all_ do this, with some populations of some species being non-migratory. Of course, there’s more, a lot more, and in the next few posts I’d like to introduce a few details that you might not have encountered before… unless, that is, you’re a cetologist, or a close friend of one.

Thanks – mostly – to aerial photography, most of us are now familiar with the true body shape of live rorquals. They are shockingly gracile and incredibly long-bodied, with a shape that (when seen in dorsal view) has been likened to that of a champagne flute. While people had known this for a while (Roy Chapman Andrews wrote in 1916 of the Fin whale’s ‘slender body … built like a racing yacht’, for example), what may or may not be surprising is that only recently have people in general come to realize that rorquals are shaped like this. Basing their reconstructions on beached carcasses, or on rorquals killed by whaling vessels, artists and scientists had previously thought that rorquals were stouter, with fat bellies and flabby throats. Rorquals were still being depicted this way as recently as the 1960s, as in (for example) the excellent paintings and drawings of Sir Peter Scott [see above, borrowed from the Wildlife in Danger Brooke Bonds card set].

By photographing live sei and minke whales, underwater, from close range, Gordon Williamson (1972) argued that the traditional ‘baggy-throat’ reconstructions failed to show the true body shape of the animals. His drawings, reconstructed from his photos (which invariably failed to capture the entire animal in the frame), were dead accurate and among the first to depict rorquals in this way. Williamson’s whales were all captured, by harpoon, from a commercial whaling vessel. No explosive was placed in the harpoon head (normally, the harpoon head explodes within the body of the whale), so a harpooned whale was not killed immediately and was simply tethered to the ship. As it swam around, gradually tiring, Williamson approached it in the water and took his photos [the accompanying image, showing a young rorqual that beached in Florida in 2002, is borrowed from VisitGulf.com].

More on rorquals in the next post, this time focusing on the biomechanics of feeding: From cigar to elongated, bloated tadpole: rorquals part II. For the latest news on Tetrapod Zoology do go here.

Refs - -

Berta, A. & Sumich, J. L. 1999. Marine Mammals: Evolutionary Biology. Academic Press, San Diego.

Stearn, W. T. 1981. The Natural History Museum at South Kensington. Heinemann, London.

Víkingsson, G. A. 1995. Body condition of fin whales during summer off Iceland. In Blix, A. S., Walløe, L. & Ulltang, Ø. (eds) Whales, Seals, Fish and Man. Elsevier Science, pp. 361-369.

Williamson, G. R. 1972. The true body shape of rorqual whales. Journal of Zoology 167, 277-286.