Wednesday, November 29, 2006

Frame 352, and all that

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 20th 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.

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Wednesday, November 22, 2006

The Madagascar pochard returns

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 19th and 20th 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 20th 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.

Thursday, November 16, 2006

Those sexy tupuxuarids

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 Usbornes 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 Wittons 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.

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Tuesday, November 14, 2006

Giant killers: macropredation in lions

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.

Sunday, November 12, 2006

Goodbye, my giant predatory, cursorial, flightless hoatzin

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.

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