Tuesday, February 28, 2006

Gambo rides again: the beaked beast of Bungalow Beach and the prehistoric survivor paradigm

In another desperate effort to destroy whatever tiny specks of credibility I might have in the scientific community, I’m going to post today about sea monsters. Yes, sea monsters, or, at least, one sea monster in particular. Most people know that various unidentified carcasses of mysterious creatures have been washed ashore over the years, and identified by lay-people as the remains of surviving prehistoric monsters. It’s true that in at least some cases these carcasses have later been identified as dead basking sharks, or as decomposing sperm whales, but there are an equal amount of other cases where no satisfactory identification has been proposed.

Of course that doesn’t automatically mean that the carcasses in question really did represent large, hitherto unknown marine animals (what we might technically term aquatic cryptids), but scientists should at least be interested enough in this possibility to look at the evidence and use their expertise in resolving these mysteries. There are two points worth making here. Firstly, it is well known (or at least I hope it is) that at least some large vertebrate species await discovery, especially marine ones (if you don’t believe me see: Paxton 1998, 2001, Raynal 2001, Solow & Smith 2005), and indeed this is constantly verified by the continuing recognition and description of new large marine vertebrates species (e.g. Mesoplodon perrini in 2002, Balaenoptera omurai in 2003, Orcaella heinsohni in 2005). Secondly, qualified scientists have looked, and do look, at the ‘sea monster’ literature, and it just isn’t fair or accurate to think that this subject isn’t worthy of good scientific attention.

A mid-length article published in 2001 included most of my thoughts on aquatic cryptids (Naish 2001). Some of the assertions made there are now outdated, or should be revised or corrected, but by and large I’m told that it’s a useful review. Unfortunately it seems that other researchers have either had trouble obtaining this article (the journal in which it was published appeared erratically, was mail-order only, and now appears impossible to obtain), or have remained completely unaware of it (and there’s the third possibility that they do have access to it, and are aware of it, but have just chosen to ignore it). While (I hope) I’m not arrogant enough to think that I hold the ultimate or most-useful opinions on this area, I do think that there are some comments and observations in the article that should be more widely acknowledged.

One of the most interesting ‘mystery carcass’ tales is that of ‘Gambo’*, a flippered sea creature apparently washed ashore on a Gambian beach in 1983. Most of the analysis and speculation about this carcass has come from prominent cryptozoologist Karl Shuker, and it’s no secret that Shuker has consistently interpreted Gambo and other cryptids as ‘prehistoric survivors’; viz, as late surviving representatives of groups otherwise thought to have gone extinct in the Mesozoic. I’ve disagreed with this on several occasions and indeed Shuker and I have been at loggerheads over what I term the ‘prehistoric survivor paradigm’ [go here for another post on this subject]. Regardless of how the reported carcass is interpreted, the significance of the case is that the exact location of Gambo’s burial site is known. Here’s where the story become topical. The new issue of Animals & Men arrived a few weeks ago, and therein is news that an official attempt to locate and exhume the carcass is to go ahead later this year (assuming, of course, that the carcass exists). Chris Moiser (of Plymouth College of Further Education) has led previous efforts to locate it while on fieldwork in the Gambia, but this time things will be done properly.

* Cryptozoologists have a really, really annoying habit of coming up with cutesy pet names for cryptids: Shuker is among them (the respective cryptozoologists, not the cutesy pet names) and coined ‘Gambo’ for use in his book In Search of Prehistoric Survivors.

So in the interests of disseminating my thoughts on Gambo to a wider audience, here is what I wrote about it in Naish (2001, pp. 88-89)…

‘Gambo’ - the Gambian sea serpent
Evidence comparable to the NHT is a carcass allegedly examined by Owen Burnham in June 1983 at Bungalow Beach, Gambia. First reported in a letter to BBC Wildlife, Burnham’s case has received publicity thanks to texts devoted to discussion of it by Bright (1989) and Shuker (1986a, b, 1993, 1995, 1996, 1998). Burnham claims he knows exactly where this is buried: no excavation there has yet been carried out. Owen Burnham was not the sole witness of the Gambian carcass: it is documented that his father, sister and brother observed it as well. That their accounts tally with his (though I understand that they reported somewhat differing measurements (G. Inglis pers. comm. 1997)) does support authenticity of the account. However, I find it very difficult to believe that, as a competent naturalist, Burnham failed to take any kind of sample whatsoever. Clearly, Burnham could not be expected to pickle the carcass, or hack through it to pull out a potentially diagnostic organ or bone, but why did he not think to retain one piece of skin, a flipper, a tooth? Furthermore, no sketches drawn from the carcass, or photographs, exist. Burnham’s several renditions of the creature were drawn on his return to the UK and not during his time in the Gambia. I bring attention to these points, not to attempt in any way to discredit Burnham or his report, but to illustrate the apocryphal and anecdotal nature of the account. As appealing as it is in potentially promising a bona fide sea serpent carcass, it is unfortunately no better than the many tales of lost sea serpent carcasses from the 18th and 19th centuries.

Burnham’s description is essentially that of a small, short-necked plesiosaur, and he is adamant that it was not a whale. The only cetacean that might conform in some features to the Gambian carcass is Tasmacetus shepherdi, the poorly known Shepherd’s or Tasman beaked whale, a species known from few specimens and only two probable sightings from the field (Watkins 1976, Laughlin 1996). Burnham discounted this species (and all other cetaceans) as the identity for the carcass and, though I feel based on Burnham’s descriptions that this identification is not satisfactory, I note that some Tasmacetus carcasses do bear more than a passing resemblance to Burnham’s drawings. Mead’s (1989) photographs of a beached Tasmacetus specimen from Punta Buenos Aires is superficially not unlike Burnham’s drawings (Fig. 8). In contrast to some artistic depictions of this species, these photos reveal an elongate, forceps-jawed rostrum, a poorly expressed melon, and prominent teeth along the lengths of the jaws. I also note some problems in Burnham’s narrative. For example, he notes that no mammary glands were present, and that any external genitalia were ‘too damaged to be recognisable’. However, the animal’s underside could not be examined so it is not clear how these observations could have been made. Preliminary excavations in the approximate area of ‘Gambo’s’ alleged burial have not been successful though, clearly, extensive excavations would be more satisfactory (Anon. 1997, Downes 1997).

The picture above is from…


Yes, Gambo has its own Wikipedia entry.

Refs - -

Anon. 1997. In search of Gambo. Animals & Men 14, 11-13.

Bright, M. 1989. There are Giants in the Sea. Robson Books (London), pp. 224.

Downes, J. 1997. Mission Impossible: the search for ‘Gambo’. Uri Geller’s Encounters 9, 50-53.

Laughlin, C. 1996. Probable sighting of Tasmacetus shepherdi in the South Atlantic. Marine Mammal Science 12, 496-497.

Naish, D. 2001. Sea serpents, seals and coelacanths. In Simmons, I. & Quin, M. (eds) Fortean Studies Volume 7. John Brown Publishing (London), pp. 75-94.

Paxton, C. 1998. A cumulative species description curve for large open water marine animals. Journal of the Marine Biologists Association, U.K. 78, 1389-1391.

- . 2001. Predicting pelagic peculiarities: some thoughts on future discoveries in the open seas. In Heinselman, C. (ed) Dracontology Special Number 1: Being an Examination of Unknown Aquatic Animals. Craig Heinselman (Francestown, New Hampshire), pp. 60-65.

Raynal, M. 2001. Cryptocetology and mathematics: how many cetaceans remain to be discovered? In Heinselman, C. (ed) Dracontology Special Number 1: Being an Examination of Unknown Aquatic Animals. Craig Heinselman (Francestown, New Hampshire), pp. 75-90.

Shuker, K.P. N. 1986a. The Gambian sea-serpent. The Unknown, September 1986, 49-53.

- . 1986b. The Gambian sea-serpent. The Unknown, October 1986, 31-36.

- . 1993. Gambo – the beaked beast of Bungalow Beach. Fortean Times 67, 35-37.

- . 1995. In Search of Prehistoric Survivors. Blandford (London), pp. 192.

- . 1996. The Unexplained. Carlton Books (London), pp. 224.

- . 1998. Fishy tales. The X Factor 45, 1249.

Solow, A. R. & Smith, W. K. 2005. On estimating the number of species from the discovery record. Proceedings of the Royal Society B 272, 285-287.

Watkins, W. A. 1976. A probable sighting of a live Tasmacetus shepherdi in New Zealand waters. Journal of Mammalogy 57, 415.

No no no no NO: the Herring gull is NOT a ring species!

So many animals that we totally take for granted are actually, when you think about them, really remarkable. In keeping with the theme of alien invaders (see previous posts on eagle owls and British big cats), I was going to talk about Collared doves Streptopelia decaocto, and the various egret species that are presently ‘invading’ the British Isles. But it’s another ordinary, yet remarkable, bird that I’m going to talk about now, and it’s the Herring gull Larus argentatus, a behaviourally flexible, adaptable and widespread bird that inhabits Eurasia and North America. It’s a large bird that can exceed 70 cm in length and have a wingspan of 1.3 m. It’s also a supreme generalist, capable of thriving on all kinds of food, and this explains its highly successful colonisation of urban environments.

While, as I said, we take urban gulls for granted, if you think about it, it’s pretty amazing that a seabird with a 1.3 m wingspan has successfully colonised towns and cities. They’ve learnt to drop shelled prey from heights in order to break it open (there’s the famous anecdote of a New Jersey highway bridge littered with clam shells dropped by enterprising gulls) and they also like to wash their food in rockpools. Their breeding behaviour and how they and their chicks respond to stimuli is tremendously well studied, with the studies of Goethe, Tinbergen and others being classic, pioneering works in ethology.

But perhaps what makes the Herring gull most ‘famous’ among biologists is it’s alleged status as the examplar par excellence of a ‘ring species’. As we’ll see below, this concept has now been all but debunked, and it’s because of this that I’m surprised whenever I see continuing references to it. Who might be the most naughty of recent offenders, I hear you ask? Richard Dawkins. Yes, he of Selfish Gene fame. I noted a while back that I was reading The Ancestors Tale (Dawkins 2004). It’s a good book, sure, but I’ve found it a tedious read (with awful artwork), and to be honest I’ve repeatedly given up on it and moved on to Mayor’s The First Fossil Hunters, Pianka & Vitt’s Lizards: Windows to the Evolution of Diversity, Patterson’s The Lions of Tsavo and Fisher & Lockley’s Seabirds [image at left, depicting the ring species concept, is from the Inside Science site].

The ring species concept is a big deal as it proposes a mechanism for one of the most important questions of evolutionary biology: the origin of species. And it was study of Herring gulls that led the late great Ernst Mayr (1942) to argue that speciation in Herring gulls had occurred by way of ‘isolation by distance’: while adjacent populations would be able to breed with one another, the genetic distance resulting from the expansion of a species far from its centre of origin would eventually produce an ‘end’ population so far removed from its ancestor that it would be incapable of interbreeding with it. It would now be a separate species. Mayr proposed that exactly this has happened, and that, after originating in the Aralo-Caspian region, Herring gulls had moved north to the Arctic Ocean. Here they expanded west, giving rise to dark-mantled forms of the Lesser black-backed gull, and also east, giving rise to the pale-mantled forms of Herring gull of Siberia and North America. Finally, North American Herring gulls crossed the Atlantic to invade Europe, and here they encountered the Lesser black-backed gulls that marked the other end of the ring. Both end points had now reached reproductive isolation, and today coexist as distinct species.

Don’t get me wrong: there’s good evidence that speciation does occur in this way in some instances (e.g. in Californian Ensatina salamanders, and southern Asian leaf warblers), but it seems to be very rare. And, as it happens, new study indicates that it did not happen in the case of Herring and Lesser black-backed gulls. Firstly, the taxa regarded by Mayr as subspecies of these two are now regarded as distinct enough to be regarded as separate species. The Aralo-Caspian gull regarded by Mayr (1942) as the ancestral Herring gull population is the Caspian or Steppe gull L. cachinnans, and the Mediterranean and eastern Atlantic gull thought by Mayr (1942) to be a westward excursion of the Caspian gull is the Yellow-legged gull L. michahellis. Furthermore, if a recently proposed subdivision of Lesser black-backed gulls is accepted (Sangster et al. 1998), then the proper name for this species is L. graellsii, and two taxa previously ranked as subspecies – the Tundra gull L. heuglini and Baltic gull L. fuscus – should be separated as species. Of course you could bring in here the debate over the whole subspecies concept: there are over 20 of these in the Herring gull-Lesser black-backed gull complex, so.. gack.. how many species should we be recognising? And once we do start to recognise at least some of these taxa as species, doesn’t this negate the whole raison d’être of Mayr’s proposed ring?

Furthermore, in a study of mtDNA in white-headed gulls, Liebers et al. (2004) found that white-headed gull phylogeny and biogeography was far more complex than Mayr and others had thought. Yellow-legged gulls [image at left] were not closest to Caspian gulls, but instead seem to have descended from a North Atlantic ancestral population. A separate ancestral population moved north from the Aralo-Caspian region toward the British Isles, giving rise to the Lesser black-backed gull, and east toward Siberia and North America, where Tundra gulls, Slaty-backed gull L. schistisagus and Glaucous-winged gulls L. glaucescens arose. Intriguingly, the Great black-backed gull L. marinus was not an outgroup to the Herring gull-Lesser black-backed complex as usually thought, but was actually nested within the complex and probably evolved (in allopatry with L. argentatus) in northeastern N. America. Glaucous gulls L. hyperboreus and Kelp gulls L. dominicanus were also nested within L. argentatus, and the discovery about the Kelp gull is interesting: this species is unique to the Southern Hemisphere, and Liebers et al. (2004) concluded that it must have evolved via long-distance colonisation ‘from the same ancestral population as the Lesser black-backed gull, suggesting that its ancestors were highly migratory, as nominate Lesser black-backed gulls still are today’ (p. 895). The central Asian L. mongolicus didn’t originate from Caspian gulls, but from Pacific gulls close to L. schistisagus.

If all of this seems horribly confusing, I think that’s because it is. The number and variety of white-headed gull taxa is baffling and sorting out any kind of historical pattern is highly, highly difficult. The picture is made more complex by the fact that populations which appear to belong to different lineages (e.g. L. michahellis from the Atlantic Iberian coast and western European L. argentatus) look similar, apparently due to convergence (Pons et al. 2004). It’s also difficult to tell whether strong genetic similarities reported between some taxa – such as Baltic gulls and Tundra gulls for example – result from recent separation or from ongoing gene flow (Liebers & Helbig 2002). There’s also the interesting discovery that supposed hybrids (of L. hyperboreus and L. argentatus) turned out to be light-winged L. argentatus founders that were expanding their range (Snell 1991).

But, most importantly, support for the simple ring model is lacking as there is no evidence that North American Herring gulls recolonised Europe to encounter the Lesser black-backed gulls that marked the other end of the ring. However, the great irony of all this is that L. graellsii is presently spreading westwards, and may eventually colonise North America. Should it do this (right now it breeds as far west as Greenland), it will encounter the North American Herring gull L. argentatus smithsonianus, and if these two forms prove incapable of interbreeding, then the ring species model would have been fulfilled… albeit it by birds moving from east to west, rather than west to east as Mayr proposed.

Well, all of that was pretty complicated. Feel free not to remember it, but take home at least the title of Liebers et al.’s paper: ‘The herring gull complex is not a ring species’. In the accompanying photo, James Coyne throws wotsits at a Herring gull on Anglesea. Coyne, where are you now?

PS - for the latest news on Tetrapod Zoology do go here.

Refs - -

Dawkins, R. 2004. The Ancestor’s Tale. Weidenfeld & Nicolson (London), pp. 528.

Liebers, D., de Knijff, P. & Helbig, A. J. 2004. The herring gull complex is not a ring species. Proceedings of the Royal Society of London B 271, 893-901.

- . & Helbig, A. J. 2002. Phylogeography and colonization history of Lesser black-backed gulls (Larus fuscus) as revealed by mtDNA sequences. Journal of Evolutionary Biology 15, 1021-1033.

Mayr, E. 1942. Systematics and the Origin of Species. Columbia University Press (New York), pp. 334.

Pons, J.-M., Crochet, P.-A., Thery, M. & Bermejo, A. 2004. Geographical variation in the yellow-legged gull: introgression or convergence from the herring gull? Journal of Zoological Systematics & Evolutionary Research 42, 245-256.

Sangster, G., Hazevoet, C. J., Berg, A. & van den Roselaar, C. S. 1998. Dutch avifaunal list: species concepts, taxonomic stability, and taxonomic changes in 1998. Dutch Birding 20, 22-32.

Snell, R. R. 1991. Variably plumaged Icelandic Herring gulls reflect founders not hybrids. The Auk 108, 329-341.

Saturday, February 25, 2006

Lots of sauropods, or just a few sauropods, or lots of sauropods?

I have a window of about 30 minutes before I need to get back to the British dinosaurs manuscript (which really needs to be finished by next week), so let’s see if I can get this done. As discussed in the previous blog entry, early last week Mike Taylor (see accompanying hilarious photo) and I spent the better part of a day working on Wealden sauropods in the Natural History Museum collections. The main point of this excursion was to have our final look (‘final’ as in last look before we submit our paper) at a specimen that we’ve been working on: a highly unusual, in fact deeply weird, new taxon collected in the late 1800s from the Ashdown Beds Formation (Valanginian) near Hastings. I won’t be saying more about it until it’s published, but its ‘discovery’ has prompted me to revisit the problematic area of Wealden sauropod diversity. Well, ok, I’m ‘revisiting’ that area anyway right now, what with the British dinosaurs manuscript, but still. Was sauropod diversity in the Early Cretaceous of England high, or low?

First things first: it’s misleading to think of the ‘Wealden’ as a short chunk of time, as this term actually applies to three formal stratigraphic groups (the Berriasian-Barremian Hastings Beds and Weald Clay Group of the mainland, and the Hauterivian-Aptian Wealden Group of the Isle of Wight). ‘Berriasian to Aptian’ is something like 30 million years, so that’s a lot of time for a whole lot of species to come and go. Whole assemblages of species in fact. Certainly the animals known from the Hastings Beds Group are not the same as those of the Barremian Wessex Formation (the best known dinosaur-bearing unit in the Wealden Group). The Hastings Beds Group has yielded Pelorosaurus conybeari (which is actually the same thing as Cetiosaurus brevis, but we won’t go there right now) and P. becklesii (which clearly isn’t congeneric with P. conybeari). P. conybeari, based on caudal vertebrae, chevrons and a large and gracile humerus, is a basal titanosauriform, perhaps a brachiosaurid. P. becklesii, named for tremendously short and robust forelimb elements and skin, is clearly a titanosaur. This is significant as it’s among the oldest of verified body fossil representing this clade. However, there are trackways that appear to have been produced by titanosaurs from the Bathonian of Ardley, Oxfordshire (Day et al. 2002, 2004), so titanosaurs had been around since the Middle Jurassic at least.

That’s not all – the Hastings Beds Group has also yielded a single metacarpal which has been identified as belonging to a diplodocid: that’s right, not just a diplodocoid, but a diplodocid. Angela Milner initially made this identification, and more recently I’ve had it verified by Matt Bonnan (pers. comm. 2006). Then we have the new taxon that Mike and I are looking it. It doesn’t seem that any of these animals can be conspecific, so, we have: a basal titanosauriform (and possible brachiosaurid), a good titanosaur, a diplodocid, and a new taxon that isn’t any of these.

What about the Wessex Formation, where 30-odd Barremian dinosaur species are known? Naish & Martill (2001) and Naish (2005) thought that sauropod diversity here was quite high, with a possible camarasaurid (Chondrosteosaurus), a few brachiosaurids, a titanosaur (Iuticosaurus valdensis), and an unnamed diplodocoid (represented by a chevron as well as isolated teeth and other elements). This now seems erroneous, or perhaps over-optimistic. The characters supposedly indicating camarasaurid status for Chondrosteosaurus are rubbish, and it’s more likely a basal titanosauriform (and it’s non-diagnostic anyway). The supposed diplodocoid bits are controversial, and the ‘sled-like’ morphology initially used to support a diplodocoid identity for the famous chevron (Charig 1980) is now thought to have been primitive for neosauropods, rather than derived for diplodocoids (see Upchurch 1998). It’s also difficult to be sure that there’s more than one brachiosaurid. The evidence for titanosaurs (procoelous caudal vertebrae, with a distinctively located neural arch) is reasonable, but the remains aren’t diagnostic.

Accordingly, when Paul Upchurch spoke about Wessex Formation sauropod diversity at the British dinosaurs Palaeontological Association Review Seminar in November 2003 (co-hosted by Dinosaur Isle Museum and the University of Portsmouth) he cautioned that diversity might have been over-estimated, and that titanosauriforms accounted for what diversity there was.

But while some groups – like camarasaurids – have now been removed from the list of taxa, new ones have been added (as it happens, camarasaurids were apparently present elsewhere in Lower Cretaceous Europe, but more about that another time). Firstly, there are definitely brachiosaurids present in the Wessex Formation: the big MIWG 7306 cervical vertebra that I and colleagues described in 2004 (Naish et al. 2004) is clearly more like the vertebrae of Brachiosaurus and Sauroposeidon than anything else (go here for more), and some of the dorsal vertebrae referred by Blows (1995) to his problematic taxon Eucamerotus foxi are also clearly brachiosaurid in the strict sense. Then there are the clearly titanosaurian caudal vertebrae, such as those described by Le Loeuff (1993). But there’s more.

A big and highly distinctive, pristine tooth forms the holotype of Oplosaurus armatus. Naish & Martill (2001), the idiots, thought that this might be another brachiosaurid, but that’s clearly wrong: Canudo et al. (2002) suggested that Oplosaurus might instead have been closer to Camarasaurus, and Upchurch et al. (2004) regarded it as a distinct neosauropod of uncertain affinities. Then there are the brachiosaurid teeth named Pleurocoelus valdensis: most authors have regarded these as non-diagnostic bits of brachiosaurid, but Ruiz-Omeñaca & Canudo (2005) have argued that they’re diagnostic and really represent a good species. Whatever they are, they’re clearly something else from Oplosaurus.

And then, finally, there are the diplodocoid teeth figured by Naish & Martill (2001) and identified by Wilson & Sereno as…. rebbachisaurid teeth! I can’t provide the citation for the latter as I don’t yet have the paper, but the recognition of these teeth as rebbachisaurid verifies the presence of diplodocoids in the Wessex Formation. Ok, so they aren’t diplodocid-like forms as Charig and others thought when they were looking at the chevron, but they’re diplodocoids nonetheless. In some senses this discovery isn’t a surprise as rebbachisaurids have lately been reported from Barremian-Aptian Spain (Fernández-Baldor et al. 2001, Pereda Suberbiola et al. 2003), but it now means that the oldest rebbachisaurids in the world are from England. Huh, so much for this being an exclusively Gondwanan clade.

So, in the Wessex Formation we have… an unusual neosauropod of uncertain affinities (Oplosaurus), definite brachiosaurids, definite titanosaurs, and a rebbachisaurid. That’s not bad in terms of diversity (adjacent picture shows diplodocoid and titanosaur). To remind you, in the older Hastings Beds Group we have a basal titanosauriform (and possible brachiosaurid), a titanosaur, a diplodocid, and a new and unusual taxon that isn’t any of these. So, also, not bad in terms of diversity, and in fact not that different from the Wessex Formation roster, which implies stability from the point of view of long-term diversity.

And, it’s on that point that I must get back to work. I was going to talk about the theropods, but that can wait.

Ref - -

Blows, W. T. 1995. The Early Cretaceous sauropod dinosaurs Ornithopsis and Eucamerotus from the Isle of Wight, England. Palaeontology 38,187-197.

Canudo, J. I., Ruiz-Omeñaca, J. I., Barco, J. L. & Royo Torres, R. 2002. ¿Saurópodos asiáticos en el Barremiense inferior (Cretácico Inferior) de España? Ameghiniana 39, 443-452.

Charig, A. J. 1980. A diplodocid sauropod from the Lower Cretaceous of England. In Jacobs, L. L. (ed.) Aspects of Vertebrate History, Essays in honour of E. H. Colbert. Museum of Northern Arizona Press, pp. 231-244.

Day, J. J., Norman, D. B., Gale, A. S., Upchurch, P. & Powell, H. P. 2004. A Middle Jurassic dinosaur trackway site from Oxfordshire, UK. Palaeontology 47, 319-348.

- ., Upchurch, P., Norman, D. B., Gale, A. S. & Powell, H. P. 2002. Sauropod trackways, evolution, and behavior. Science 296, 1659.

Fernández-Baldor, T., Pereda Suberiola, X., Huerta Hutado, P., Izquierdo, L. A., Montero, D. & Pérez, G. 2001. Descripción preliminar de un dinosaurio rebaquisáurido (Sauropoda Diplodocoidea) del Cretácico Inferior de Burgos (España). II Jornadas de Paleontología de Dinosaurios y su Entorno. Salasa de los Infantes (Burgos, España), 203-211.

Le Loeuff, J. 1993. European titanosaurs. Revue de Paléobiologie 7, 105-117.

Naish, D. 2005. The sauropod dinosaurs of the Wealden succession (Lower Cretaceous) of southern England. The Quarterly Journal of the Dinosaur Society 4 (3), 8-11.

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.

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.

Pereda Suberbiola, X., Torcida, F., Izquierdo, L. A., Huerta, P., Montero, D. & Perez, G. 2003. First rebbachisaurid dinosaur (Sauropoda, Diplodocoidea) from the early Cretaceous of Spain : palaeobiogeographical implications. Bulletin de la Societe Geologique de France 174, 471-479.

Ruiz-Omeñaca, J. I. & Canudo, J. I. 2005. “Pleurocoelusvaldensis Lydekker, 1889 (Saurischia, Sauropoda) en el Cretácico Inferior (Barremiense) de la Península Ibérica. Geogaceta 38, 43-46.

Upchurch, P. 1998. The phylogenetic relationships of sauropod dinosaurs. Zoological Journal of the Linnean Society 124, 43-103.

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.

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Friday, February 24, 2006

Luis Rey and the new oviraptorosaur panoply

Earlier this week I spent a few days in London: Mike Taylor and I had arranged to work in the collections of the Natural History Museum on Wealden sauropods. We have what appears to be a new taxon (more on that in future). I also took the opportunity to complete some of my research on large Wealden theropods. On the way, I stopped off and stayed with Luis Rey and his partner Carmen, and it’s the fantastic new stuff Luis showed me that I want to discuss here. I haven’t had access to my computer for a few days, so this is being posted later than planned.

Right now Luis is very busy doing the artwork for a major new book on dinosaurs written by Tom Holtz. Judging from the art I’ve seen, it will be spectacular and one of the most attractive dinosaur books ever. Several plates depict a taxonomic panoply of a particular group, and we also have the first accurate life restoration of the bizarre Lurdusaurus, as well as new restorations of Dilong, Guanlong, Scutellosaurus and so many others. What caught my imagination in particular were his restorations of the amazing diversity of recently named oviraptorosaurs (a black-and-white version depicting this diversity has been published before (Gee & Rey 2003), but it did not include as many taxa). In fact there are now so many members of this group that it is proving difficult to keep up, and difficult to keep track of what is what, especially given that several specimens have been incorrectly allocated to a genus and later re-allocated or re-named. In fact several discoveries relevant to this area have appeared in recent months and I’ve only just done reading them, so now is a good time to review it.

Most of the new taxa belong to the oviraptorosaurian clade Oviraptoridae (more basal members of Oviraptorosauria include the caenagnathids, Avimimus, Caudipteryx and Microvenator). It has been proposed that Oviraptoridae consists of two radiations: the mostly crested oviraptorines, and the crest-less ingeniines, though some recently described taxa do not fit neatly into this dichotomy. Starting with the oviraptorines, we begin with Oviraptor philoceratops, the first of them to be named (Osborn 1924). Ironically, it’s not that well known and the fact that, until recently, most Mongolian oviraptorids were assumed to be referable to this genus means that very few illustrations of Oviraptor really do depict this genus. It turns out that Oviraptor was comparatively long-skulled for an oviraptorid and it may have been the most basal oviraptorine (Clark et al. 2002). Some kind of premaxillary crest was present, but the skull is not well preserved enough to determine its original shape.

Long labelled as a new species of Oviraptor is the tall-crested animal now known as Rinchenia mongoliensis. The generic name has been kicking around for a while but its formal use in a major compendium (Osmólska et al. 2004) means that it is now ‘officially’ in use. In Rinchenia the crest is mound-shaped and extends for most of the length of the skull. There is another specimen often illustrated as an Oviraptor – in fact normally labelled as Oviraptor philoceratops (e.g., Barsbold et al. 1990) – and this is GIN 100/42. It is short-skulled and sports a rounded crest decorated with lateral accessory openings. Though regarded by some as a new species of Citipati (on which see below), one unpublished study found it to be closest to O. philoceratops. Whatever, ‘because [GIN 100/42] is much better preserved than the holotype of O. philoceratops it has often been relied upon for anatomical details of this species, so caution should be used in referring to previous characterization of this species’ (Clark et al. 2002, p. 21). It’s a new taxon, whatever its affinities.

Finally among the oviraptorines, there is Citipati osmolskae. This was a large animal compared to most other oviraptorids with a distinctive rostrodorsally inclined back part to the skull, a large, sub-oval naris, and a premaxillary crest that is continuous with the premaxilla’s rostral margin (Clark et al. 2001). The famous ‘big momma’ specimen (an animal preserved atop an egg-filled nest), and an embryonic specimen, also appear referable to Citipati. The embryo is significant in that it was the specimen that demonstrated that most/some eggs attributed to Protoceratops were actually oviraptorid eggs. I don’t have time to cover that story in depth now, and it’s reasonably well known now anyway. Not all studies agree that Citipati is an oviraptorine – it may instead be an ingeniine.

We move now to the ingeniines, a group separated from oviraptorines by Rinchen Barsbold, mostly due to differences in hand structure (Barsbold et al. 1990). Barsbold later thought that ingeniines were distinct enough to deserve their own ‘family’, Ingeniidae, though this has not been supported by more recent studies. The type taxon of the group is 'Ingenia' yanshini, a small, robust species (‘small’ = c. 1.5 m long) with particularly short arms, a massive thumb, and robust, short feet. It has recently been discovered that the name 'Ingenia' is preoccupied, and this explains the quotes used here. A replacement name will appear at some stage, but hasn't done so yet. Rather similar to 'Ingenia', though more gracile, is Conchoraptor gracilis. The short, rounded skull of this species has been illustrated and labelled several times as representing Oviraptor, though it is clearly distinct from that taxon. It has a distinctive subvertical, dorsoventrally elongate naris. Khaan mckennai*, described for two outstanding complete skeletons, is similar to Conchoraptor but has a more horizontally-aligned naris and more strongly curved manual unguals (Clark et al. 2001).

*If I remember correctly, the ICZN prefers it if 'Mc' names are converted to 'mac' spellings when used in binomials. If this is right, then the specific name here should really have been 'mackennai'. As an example, the ichthyosaur Macgowania was named for Chris McGowan.

Also probably part of Ingeniinae is Heyuannia huangi, a taxon named in 2002 and known from at least four individuals, one of which is an almost complete skeleton (Lü 2002, Lü et al. 2005). It was also small (less than 2 m long), crest-less, with a longer neck and shorter back than other taxa, and a particularly long ilium.

The most recently named oviraptorid is Nemegtomaia barsboldi from the Maastrichtian Nemegt Formation (Lü et al. 2004, 2005). Lü et al. (2004) originally named this taxon Nemegtia, but that turned out to be preoccupied by an ostracod from the Nemegt Formation (shades of 'Ingenia'). Nemegtomaia is reasonably well known, with a near-complete skull. Prior to this, the specimen had been figured, but identified (without good reason) as a new specimen of 'Ingenia' (Lü et al. 2002). However, unlike 'Ingenia', Nemegtomaia is an oviraptorine, and it’s probably closely related to Citipati.

We also have Shixinggia oblita from the Maastrichtian Pingling Formation of Guangdong Province, China, and known from pelvic, hindlimb and vertebral material (Lü & Zhang 2005). The affinities of this taxon are uncertain – it may be a caenagnathid and not an oviraptorid. For various reasons I’m very interested right now in postcranial pneumaticity, and for this reason I’ll say that Shixinggia (and Heyuannia) are particularly interesting. More on that later.

Also on the subject of caenagnathids, there is Hagryphus giganteus, just described from the Campanian Kaiparowits Formation of Utah (Zanno & Sampson 2005). Though only known from a hand, a fragmentary distal part of a radius and some fragments from the foot, it’s clearly distinct from other North American taxa. It was large – bigger even than Chirostenotes (and ‘large’ here means >3 m long). And this isn’t the end of it as at least a few other taxa (mostly oviraptorids) have been figured in the literature and appear to represent valid taxa, but have yet to be named or described.

The expanding taxonomic sample and diversity of these animals is the exciting area that I’ve covered here, but there’s so much other interesting stuff that could be said about oviraptorosaurs. There’s what we know of their reproductive behaviour (gleaned from nests with eggs and even shelled eggs discovered inside a pelvis), the affinities and anatomy of the basal forms from Lower Cretaceous China (Caudipterx, Protarchaeopteryx and Incisivosaurus), the controversy over their diet and ecology, their controversial phylogenetic position (some workers maintain that they are flightless birds*), and the controversy over their alleged presence in the English Lower Cretaceous (Naish & Martill 2002).

*Let me take this opportunity to point out that analysis of the data indicates that this view is erroneous, and that these theropods are outside of the clade that includes archaeopterygids and modern birds.

In the photo above, Luis is holding a caudal vertebra from a hadrosaurid that bears a deep score mark across its surface. The score mark matches precisely the dimensions of a tyrannosaurid premaxillary tooth tip, as Luis is demonstrating with the help of a handy set of tyrannosaurid premaxillae he just happens to own. Awesome stuff.

So what happened when I actually got round to doing some work? News on that soonish. It’s snowing here.

PS - for the latest news on Tetrapod Zoology do go here.

Refs - -

Barsbold, R., Maryańska, T. & Osmólska, H. 1990. Oviraptorosauria. In Weishampel, D. B., Dodson, P. & Osmólska, H. (eds) The Dinosauria. University of California Press (Berkeley), pp. 249-258.

Clark, J. M., Norell, M. A. & Barsbold, R. 2001. Two new oviraptorids (Theropoda: Oviraptorosauria), Upper Cretaceous Djadokhta Formation, Ukhaa Tolgod, Mongolia. Journal of Vertebrate Paleontology 21, 209-213.

- ., Norell, M. A. & Rowe, T. 2002. Cranial anatomy of Citipati osmolskae (Theropoda, Oviraptorosauria), and a reinterpretation of the holotype of Oviraptor philoceratops. American Museum Novitates 3364, 1-24.

Gee, H. & Rey, L. V. 2003. A Field Guide to Dinosaurs. Quarto Publishing (London), pp. 144.

Lü, J. 2002. A new oviraptorosaurid (Theropoda: Oviraptorosauria) from the Late Cretaceous of southern China. Journal of Vertebrate Paleontology 22, 871-875.

- ., Dong, Z., Azuma, Y., Barsbold, R. & Tomida, Y. 2002. Oviraptorosaurs compared to birds. In Zhou, Z. & Zhang, F. (eds). Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution. Science Press (Beijing), pp. 175-189.

- ., Tomida, Y., Azuma, Y., Dong, Z. & Lee, Y.-N. 2004. New oviraptorid dinosaur (Dinosauria: Oviraptorosauria) from the Nemegt Formation of southwestern Mongolia. Bulletin of the National Science Museum, Tokyo, Series C 30, 95-130.

- ., Tomida, Y., Azuma, Y., Dong, Z. & Lee, Y.-N. 2005. Nemegtomaia gen. nov., a replacement name for the oviraptorosaurian dinosaur Nemegtia Lü et al., 2004, a preoccupied name. Bulletin of the National Science Museum, Tokyo, Series C 31, 51.

- . & Zhang, B.-K. 2005. A new oviraptorid (Theropod [sic]: Oviraptorosauria) from the Upper Cretaceous of the Nanxiong Basin, Guangdong Province of southern China. Acta Palaeontologica Sinica 44, 412-422.

Naish, D. & Martill, D. M. 2002. A reappraisal of Thecocoelurus daviesi (Dinosauria: Theropoda) from the Early Cretaceous of the Isle of Wight. Proceedings of the Geologists’ Association 113, 23-30.

Osborn, H. F. 1924. Three new Theropoda, Protoceratops Zone, central Mongolia. American Museum Novitates 144, 1-12.

Osmólska, H., Currie, P. J. & Barsbold, R. 2004. Oviraptorosauria. In Weishampel, D. B., Dodson, P. & Osmólska, H. (eds) The Dinosauria, Second Edition. University of California Press (Berkeley), pp. 165-183.

Zanno, L. E. & Sampson, S. D. 2005. A new oviraptorosaur (Theropoda, Maniraptora) from the Late Cretaceous (Campanian) of Utah. Journal of Vertebrate Paleontology 25, 897-904.

Sunday, February 19, 2006

British big cats: how good, or bad, is the evidence?

The motto for my blog posts may become ‘better late than never’, as I planned to write the following some weeks ago. I don’t really have time to do it, but seeing as I feel good about getting some ‘work’ finished (my review of Tidwell & Carpenter’s Thunder-Lizards volume) I may as well get it over and done with. Plus I don’t feel like doing any more proper work anyway. More on the systematics and historical taxonomy of obscure British dinosaurs? Ugh. More on that in future here, anyway.

On Tuesday 7th of this month I gave my British big cats talk to the Southampton Natural History Society. It was entitled ‘British big cats: how good is the evidence?’, and it went well (which is a good job, as I’m giving the same talk again on March 5th, this time at the Hawthorns Study Centre on Southampton Common). Before I get down to business on the subject of alien big cats (as they’re known: ABCs from hereon), let me say that if you’re interested in natural history, do yourself a favour and join your local natural history society. After planning it for about 10 years, I finally did this a couple of years ago, and it is one of the most rewarding things I’ve done. Granted, over 70% of my fellow members are over 65 years old, but I get a lot out of the indoor meetings, and enjoy the field meetings (when I can attend them). Moving on…

As someone trying to gain a reputation as a credible scientist, it is not in my interest to declare my fascination with ABCs and related subjects. This is generally regarded, especially in academic circles, as a crackpot area inhabited only by the lunatic fringe. Unfortunately this stigma – accentuated by the half-serious, sensationalised way the subject is treated by journalists – has tarnished what is actually a perfectly sensible area for which good scientific data exists. When analysed by qualified scientists (whether they be field ecologists, laboratory-based specialists, or image analysts, or whatever), the results have been mostly positive. I start my talks on this subject by emphasizing that I do not ‘believe’ in ABCs (meaning that I do not accept their reality without question, as this is what is meant by the term ‘believe’ – see Arment (2004) for more on that if you’re interested). Furthermore, I have tried my best to maintain an appropriately sceptical approach. Like any scientist approaching a problem, I have come to the conclusions that I have because that is where the evidence has led me.

And having become acquainted with the large amount of data, I have a dilemma. On the one hand I feel that the data is so compelling that we should accept ABC reality without question, and proceed with the realisation that ABCs are undoubtedly genuine. But on the other hand I feel that more, and better, evidence is required for us to be so confident. Let me make this clear: the evidence is outstanding, and none of the doubts expressed about this subject have any standing. It’s often said that, if ABCs are real, then why don’t we have good photos, why don’t we have dead bodies, why don’t we have captured live animals, and why don’t we have definitive track and sign evidence? Well, the news is that we do have good photos, we do have dead bodies, we do have captured live animals, and we do have definitive track and sign evidence. This data is out there for anyone that’s prepared to examine it. Why isn’t this more widely known? That’s the mystery. The negative stigma attached to the subject seems to mean that the good data doesn’t really get out, at least to those people who haven’t gone to the trouble of immersing themselves in the subject.

Before I continue I should add that Britain only has, officially, two native felids: Scottish wildcats F. silvestris and Kellas cats. There is considerable disagreement as to whether the former should be kept as a distinct species: if Scottish wildcats are conspecific with the domestic cat F. catus, then African wild cats F. lybica and Indian desert cats F. ornata should be too – they’re even closer to F. catus, and indeed F. lybica is probably ancestral to domestics. Indeed it is even doubted by some as to whether purebred wildcats exist in Britain anymore. Others, however, regard it as useful to keep F. silvestris as distinct (see French et al. 1988, Daniels et al. 1998, Kitchener 1998, Reig et al. 2001, Pierpaoli et al. 2003). Kellas cats, only discovered in 1984, are introgressive domestic cat x wildcat hybrids that appear to be evolving their own unique behaviour and morphology and, by inference, into a new species (Shuker 1990).

On to the ABC evidence itself, firstly, there are hairs, tracks and droppings that have been conclusively identified by experts as having come from non-native felids. Cat hairs recovered from a site in Lincolnshire in 2003 were confirmed by a government-accredited laboratory as having come from a member of the genus Panthera. Droppings collected in 1993 from Whorlton, County Durham, were identified by Hans Kruuk as from a Puma Puma concolor. This is a big deal because Kruuk is a world authority on the field biology and ecology of carnivorans, and he’s otherwise been openly sceptical of the existence of ABCs. Finally, a large number of trackways from various locations across the UK seem to be big cat tracks. That is, they possess the diagnostic features seen in cat tracks, but not in those of dogs and other carnivorans. It is, however, admittedly difficult to be really sure on tracks, and many of the alleged ABC tracks that I’ve seen – while probably produced by cats – leave room for doubt.

It is well known that huge number of livestock kills have been blamed on ABCs. It’s often said that the way an animal has been killed – the apparent ‘neatness’ of the wound and resulting feeding sign, and the fact that the animal seems to have been killed by an attack to the throat – is indicative of a big cat as killer. This might be valid, but it’s very difficult to be confident about, so I hesitate in regarding livestock kills as that informative. There is, however, one specific case that stands out head and shoulders above the others: the Cupar roe deer carcass. There is so much that could be said about this case that I can’t cover it here (go here for more info). There is no doubt in my mind that this animal was killed by a big cat, and it was found (by Ralph Barnett, a journalist with no prior interest in the ABC phenomenon) on a small country road in Scotland.

Similarly compelling are dead bodies. Yes, dead bodies of British ABCs. Multiple specimens are now known from the UK, and they show that several species of exotic felids are (at least at times) abroad in the British countryside. They include several Jungle cats Felis chaus, five Leopard cats Prionailurus bengalensis, and a Eurasian lynx Lynx lynx, shot dead in East Sussex in 1991 (Shuker 1995). The lynx is particularly interesting as the case was pretty much kept quiet until 2001. I don’t hold much faith in conspiracy theories, but the farmer who shot this animal was told by the police to keep it to himself. In fact it’s not difficult to think that, if any official body (say, the police, or the government) does know that ABCs are an undoubted reality, they will likely not want this to become widely known. Two live exotic felids have been captured in Britain: a puma called Felicity, and a lynx called Lara. Both animals have been regarded as escapees from private collections, but this is missing the point given that surely all British ABCs are escapees from private collections (read on).

Finally, an increasing number of still photos and sequences of video footage are definitive and clearly show British ABCs. They also depict assorted species. An excellent photo taken by Peter Nixon at County Durham in 1992 clearly shows a Jungle cat, a black leopard was photographed a few times as it ran across a hillside at Tonmawr, Wales, by Di Francis in 1982, and a large cat that is either a puma or black leopard was photographed in November 1988 by Tim Young at Zennor, Cornwall (this photo is on the cover of Nigel Brierley’s They Stalk By Night). My favourite images come from a short sequence of video footage filmed at Great Witley, Worcestershire, by Nick Morris in May 1992 (a still from this sequence is shown above). The animal is a black leopard (though this is only really clear when the original colour footage is viewed). There are other bits of excellent, definitive photographic evidence – those I’ve mentioned are my favourite ones.

So what does all this mean? The conclusion is that the evidence for the presence of exotic felids in the British countryside is overwhelmingly good, and it can’t seriously be doubted that the animals are here. The Cupar roe deer carcass, definitive hairs, droppings, outstanding photographic data, and dead bodies and captured animals, provide compelling data for the contention that ABCs are real. Notable efforts to find evidence that resulted in negative conclusions (Baker & Wilson 1995, Weidensaul 2002) did so because, I think, they didn’t look at enough data. This was particularly obvious in the case of Baker & Wilson’s study (produced for the Ministry of Agriculture Fisheries and Food) – they only looked at four pieces of photographic data, for example, and had a total budget for their study of £8200 (Moiser 2001). Exotic cats of several species are here, and in fact the term ABC is a misnomer, as a significant percentage of the animals are not big cats in the strict sense of the word, but members of various small cat lineages. I assume that, because these cats are rather larger than domestic cats, they are therefore assumed to be ‘big cats’. That goes even for Jungle cats, which are about a third bigger than a domestic moggie, but no where near the size of a puma or leopard.

The great mystery I suppose is why these cats are here. They are not natives, and even though we now know that lynxes were here until about 1000 years ago, it is implausible that mammals this large could remain undetected in such small, crowded islands. They are escapees from collections, or animals that have been deliberately introduced. Can an exotic felid survive in the British countryside? Yes, without doubt. In fact a Clouded leopard Neofelis nebulosus that escaped from Howletts Zoo in 1975 survived for nine months in the wild until it was shot, and it was healthy and in good condition. Yet this is one of the most specialised, tropical cats of them all.

I could go on but I need to stop there. Comments are welcome, and further points relative to this subject will be covered in future posts. And to those of you reading this that live in my area, do come along to my next talk and see the data for yourselves.

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

Refs - -

Arment, C. 2004. Cryptozoology: Science & Speculation. Coachwhip Publications (Landisville, Pennsylvania), pp. 393.

Baker, S. J. & Wilson, C. J. 1995. The evidence for the presence of large exotic cats in the Bodmin area and their possible impact on livestock. ADAS, Ministry of Agriculture Fisheries and Food, pp. 16.

Daniels, M. J., Balharry, D., Hirst, D., Kitchener, A. C. & Aspinall, R. J. 1998. Morphological and pelage characteristics of wild living cats in Scotland: implications for defining the ‘wildcat’. Journal of Zoology 244, 231-247.

French, D. D., Corbett, L. K. & Easterbee, N. 1988. Morphological discriminants of Scottish wildcats (Felis silvestris), domestic cats (F. catus) and their hybrids. Journal of Zoology 214, 235-259.

Kitchener, A. C. 1998. The Scottish wildcat – a cat with an identity crisis? British Wildlife 9, 232-242.

Moiser, C. 2001. Mystery Cats of Devon and Cornwall. Bossiney Books (Launceston).

Pierpaoli, M., Birò, Z. S., Herrman, M., Hupe, K., Fernandes, M., Ragni, B., Szemethy, L. & Randi, E. 2003. Genetic distinction of wildcat (Felis silvestris) populations in Europe, and hybridisation with domestic cats in Hungary. Molecular Ecology 12, 2585-2598.

Reig, S., Daniels, M. J. & Macdonald, D. W. 2001. Craniometric differentiation within wild-living cats in Scotland using 3D morphometrics. Journal of Zoology 253, 121-132.

Shuker, K. P. N. 1990. The Kellas cat: reviewing an enigma. Cryptozoology 9, 26-40.

- . 1995. British mystery cats – the bodies of evidence. Fortean Studies 2, 143-152.

Weidensaul, S. 2002. The Ghost With Trembling Wings. North Point Press (New York), pp. 341.

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Friday, February 17, 2006

Walter Rothschild and the rise and fall of Sclater’s cassowary

So, besides whales, dinosaurs and giant killer eagles, one of my favourite subjects is that of giant flightless birds. The accompanying picture depicts a life-sized model of a phorusrhacoid - followers of previous things I've written will realise the significance of the colour scheme (Dan Varner are you listening?). Having spent the day so far on obscure Cretaceous vertebrates from the Iberian Peninsula, and on dull editorial work, I thought I'd waste some time and post the following entry on - sorry - not phorusrhacoids, but cassowaries. It's an extract from a much longer article I published on them a few years ago. Of all birds surely they are the coolest. Gary Cunningham, world authority on the dobhar-chu, phoned last night while I was out. Sorry I missed your call Gary. In view of the message he left I was going to produce a post about extinct sea otters, but I've decided to keep the information I have to another time. So on to cassowaries. Well, on to one cassowary in particular. Hmm, if only I had a picture of it....

Lord Walter Rothschild (1868-1937) was quite probably the most important and prolific collector of zoological specimens during the late 19th and early 20th centuries. Working from his museum and home at Tring, Hertfordshire (still the site of both his museum and the BMNH bird collections), he amassed an unparalleled collection of literally thousands of insects, bird eggs, bird skins, mammal skins and other specimens. Rothschild appears to have been specially, if not almost fanatically, interested in a number of very specific groups of animals, among which were birds of paradise (see Fuller 1995), fleas, and cassowaries.

Amassing one of the biggest single collections of cassowaries in the world, Rothschild’s collection included no fewer than 62 mounted cassowaries. These specimens evidently prove rather problematic for the curators at Tring and Whitehead & Keates (1981) write ‘... for some reason Lord Rothschild decided to have no less than 65 [sic] of these large cassowaries mounted as if for future exhibition, and as such they make a unique collection and something of a headache for the curator’. This collection is augmented by many skins and skeletal specimens! Rothschild demanded that special attention be given to the mounting of cassowaries, and he only regarded one taxidermist - a man named Doggett - as able to complete the task with satisfactory results. Doggett was paid £30 per cassowary mount by Rothschild; a sum regarded as extraordinarily high by Rothschild’s curators and relatives and consequently curtailed in 1908 by Charles Rothschild, Walter’s brother. The more than 60 mounted specimens eventually cost over £2000.

Studying these specimens with the aim of producing a monograph describing the different forms, Rothschild regarded it as essential that his descriptions were based on live specimens, not just on skins, so he collected all the cassowaries he could to keep and observe. Little has been published on how Rothschild and his staff maintained the birds, but it is known that they were not kept in a tropical house, nor heated at all. He once wrote, “My laying female has lived through 6 English winters without heat” (Rothschild 1983, p. 103). Given that cassowaries are famous for being pugnacious, one wonders if the cassowaries were ever the cause of any trouble. Indeed, cassowaries were partially responsible for the harsh attitude Rothschild’s father (Nathaniel Rothschild) had of his son’s collection for, in 1888, one of the cassowaries which roamed free in Tring Park attacked Nathaniel’s horse. However, Rothschild did complete his work and, in 1900, published his definitive monograph on the birds (Rothschild 1900). It is a lavishly illustrated work in which several new forms are named based on the colour of their necks or configuration of their wattles - features now regarded as too variable for much basis in taxonomy.

Though it might seem that Rothschild’s work on cassowaries had now reached fruition, he continued to collect the birds and started to amass a secret collection of live specimens. While his father was prohibiting the further purchase of specimens, Rothschild wrote to his collectors to continue shipping live cassowaries, but to keep them at a safe location, rather than send them straight to Tring.

Rothschild had a dark secret: he was being blackmailed by a wealthy aristocratic former mistress. Aided by her husband, this woman eventually forced Rothschild, in 1931, to sell the better part of his ornithological collection to the American Museum of Natural History for $225,000 - about a dollar a specimen. The blackmailer remains anonymous but Miriam Rothschild (1983) stated that she is aware of her true identity. Despite this tremendous and devastating loss, Rothschild could not part with his cassowaries and all of the specimens - the mounts, skins and skeletons - were retained at Tring. Today they represent an invaluable collection with a fascinating history.

Sclater’s cassowary (Casuarius philipi), was named by Rothschild in 1898 for a captive specimen kept in the Zoological Gardens at London. Shipped from Calcutta and named in honour of Philip Sclater (who is also commemorated in the name of a C. casuarius subspecies), it was probably captured in New Guinea and is worthy of note because of the extraordinary morphology Rothschild described for it. In fact, to Rothschild, Sclater’s cassowary was the most distinctive of all cassowaries.

On naming the species in 1898, Rothschild thought that, despite its brown feathers, it was fully grown and therefore unlike other cassowaries in colour. Over the years however, its feathers turned as black as those of any other cassowary. However, others of its features remained highly unusual. Not only were its feathers structurally more like those of an emu than of a cassowary, the feathers from its rump and tail region were extraordinarily long – so long that they dragged on the ground. Its casque was described as intermediate between that of C. unappendiculatus and C. bennetti, being compressed rostrally but mound-like caudally. Its call reportedly ‘resembled a deep roar’ and was unlike that of other cassowaries. Most remarkably, however, it had notably stout, short legs and, though it was large bird (Rothschild described it as ‘a giant’), it was lower to the ground than any other of the large cassowaries, being equal in height to the small Bennett’s cassowary. Rothschild even likened Sclater’s cassowary to Pachyornis, the stout-legged moa, a moa famous for its large size but thickset, short-legged frame. Fascinating as this animal sounds, it is now regarded as an individual of C. unappendiculatus. Despite Rothschild’s confidence about the distinctive nature of Sclater’s cassowary, it was apparently still a juvenile or subadult during the time that Rothschild was describing it. Its bizarre feathers and unusual proportions were purportedly due to individual variation and perhaps its lifestyle in captivity. Nevertheless it sounds like a remarkable bird.

In his writings on cassowaries, Rothschild’s greatest mistake was perhaps to recognise distinct species whenever he encountered a cassowary which had a particularly bold colour pattern on its head and neck. This propensity to recognize multiple species based on small differences was even commented on by his sister-in-law and his employees during his lifetime (Rothschild 1983), and should not be regarded as a criticism unique to this enlightened age.

Refs - -

Fuller, E. 1995. The Lost Birds of Paradise. Swan Hill Press (Shrewsbury, UK).

Rothschild, M. 1983. Dear Lord Rothschild: Birds, butterflies and history. Balaban Publishers (Glenside, Pennsylvania).

Rothschild, W. 1900. A monograph of the genus Casuarius. Transactions of the Zoological Society, London 15, 109-148.

Whitehead, P. J. P. and Keates, C. 1981. The British Museum (Natural History). P. Wilson (London).

Thursday, February 16, 2006

When whales walked the land… and looked like antelopes… and mimicked crocodiles…. and evolved trunks. What?

Note for visiting cryptozoologists (added December 2006): nowhere in this article do I say that remingtonocetids might have had trunks. Rather, the reference to a trunked whale refers to Makaracetus bidens, an unusual Pakistani protocetid described in 2005. More details on it in future (for the latest news on Tetrapod Zoology go here).

Everybody interested in animals is, I assume, fascinated by whales, and one of the most interesting topics in mammal evolution surely has to be the evolution of whales from their terrestrial ancestors. As a relatively well documented macroevolutionary tale (Thewissen & Bajpai 2001), the transition integral to this story is informative on so many levels (see Carl Zimmer’s At the Water’s Edge for a good, though now dated, overview). For me, the early evolution of whales has become particularly interesting for two reasons. Firstly, it’s controversial, and particularly so within recent years. A cherished idea of cetacean affinities – namely, the notion that whales descend from mesonychians – has been usurped by the originally unpopular and crazy notion that whales might be close relatives of hippos.

Secondly, it’s an area illuminated by novelty: specifically, by lots of newly recognised taxa. It turns out that Eocene taxa, the so-called archaeocetes, weren’t just seal-shaped amphibious protowhales: they were a motley assortment that got up to all sorts of things. Believe it or not, they included saltatorial deer-like forms, macropredatory crocodile-mimics, diminutive long-tailed forms that looked like giant desmans, ‘megaseals’ and forms sporting tapir-like trunks. Several of the taxa I have in mind are new (as in, published in 2004 or 2005), and already a review article I wrote on basal cetaceans (Naish 2004) is out of date.

Though basal whales less specialised for aquatic life than modern forms had been known since the 1830s (these being basilosaurids and dorudontids), it was only in 1904 that fossil whales truly reminiscent of their terrestrial ancestors were discovered. Two new species from Lutetian (middle Eocene) rocks of Egypt, Protocetus atavus and Eocetus schweinfurthi, were described by Eberhard Fraas in that year. With their geological antiquity (they were, at the time, the oldest of all whales), relatively small body size (3-4 m, compared to 5-20 m for basilosaurids and dorudontids), and teeth and vertebrae more similar to those of typical land mammals than to those of other whales, they were clearly the most primitive of all whales then known and were deemed worthy of their own new family, Protocetidae Fraas, 1904. However, exhibiting an elongate rostrum and uniquely shaped dense-boned ear capsules, they were clearly still members of Cetacea. Numerous discoveries of fossil whales similar to Protocetus and Eocetus have since shown that protocetids and their relatives experimented with a variety of lifestyles in and adjacent to the marine environment. Discoveries of Protocetus-like material in North America (Kellogg 1936) also show that these animals were geographically widespread.

During the 1970s and 80s emphasis in basal whale research began to shift from Africa to Asia, at first because Sahni & Mishra (1972) described primitive whale remains discovered in India, and later as West (1980) figured and identified lower jaw specimens from Pakistan. Sahni & Mishra (1972) regarded their material as representing two new species of Protocetus, P. sloani and P. harudiensis, the new taxon Indocetus ramani, and two new basal odontocetes, Andrewsiphius kutchensis and A. minor. Their Protocetus species have since been shown to be referable to a new genus that is part of a newly recognised, highly unusual basal whale group, Remingtonocetidae (Kumar & Sahni 1986). Andrewsiphius also proved to be a remingtonocetid. West (1980) also named a Pakistani specimen as a new species of Protocetus - P. attocki (but see below) - and also formalised previous suggestions that two tooth-based Pakistani mammals, Ichthyolestes pinfoldi and Gandakasia potens, were not mesonychians, as they had been originally described, but basal whales. By now, the number of Asian basal cetacean taxa had exceeded the African count.

The next most significant basal cetacean discovery was announced in 1981 when Gingerich & Russell (1981) described the well preserved but incomplete skull of the new genus and species Pakicetus inachus. West’s P. attocki proved to be a second species. With a number of unique cetacean ear bone characteristics, Pakicetus was interpreted as a probably amphibious predator that was transitional between terrestrial, wolf-like mesonychians, the probable ancestors of whales (or so it was thought at the time), and larger, younger archaeocetes like the basilosaurids. The ear bones of Pakicetus are uniquely intermediate between those of land mammals and those of derived cetaceans (Gingerich et al. 1983) and, coupled with its presence in shallow freshwater environments, suggest that it was not yet a fully marine animal.

With only a partial skull to go on, Pakicetus was assumed to be seal-like, and conventional life restorations depict it that way. We now know that these restorations are wildly inaccurate, as associated pakicetid skeletons show that these mammals weren’t all that different, superficially, from basal ‘slinker-type’ artiodactyls such as chevrotains, small deer and basal Eocene forms (Thewissen et al. 2001). In fact we also now know that pakicetids had the double-pulley astragalus regarded as unique to artiodactyls, so now it seems that artiodactyls and cetaceans were closer to one another than cetaceans were to mesonychians. Far from being seal-like protowhales, pakicetids – the most basal members of the cetacean radiation – were more like carnivorous little antelopes, though presumably they spent at least some time in shallow water.

After Pakicetus, perhaps the most important basal whale discovery was that of Ambulocetus natans, a Pakistani whale a few million years younger than Pakicetus (Thewissen et al. 1994). With a dorsoventrally mobile back and huge, long-toed feet, Ambulocetus appears suited for competent movement on land, but probably swam by powerful up-and-down oscillation of the back and paddling with the hindlimbs. Its elongate tail was not powerfully muscled and does not have the special square-shaped vertebrae required to support a tail fluke.

In contrast to pakicetids, Ambulocetus had a narrow snout and laterally directed orbits, relatively short legs, and an overall robust skeleton. An intriguing possibility regarding the palaeobiology of Ambulocetus is that it was a crocodile-like ambush predator that stalked prey while concealed in shallow water (Thewissen et al. 1996). This conclusion is based on the crocodile-like skull of Ambulocetus: both groups have long but robust snouts, pointed teeth, strong jaw-closing muscles and eyes located high up on the head.

Ambulocetus also exhibits unusual and extensive tooth wear which indicates that it fed on bony prey. If the crocodile analogy is viable, what might Ambulocetus have preyed on? Anthracobunids, a group of herbivorous ungulates probably related to elephants, and sirenians both lived in the same environments as Ambulocetus. Thewissen et al. (1996) suggested that Ambulocetus might have preyed upon these animals, as well as other animals that may have approached the shoreline.

However, given that large crocodiles were already common in the marine and freshwater environments frequented by Ambulocetus, this theory has a flaw. Indeed, it has been pointed out that primitive cetaceans may have suffered from extensive crocodilian competition and predation. Perhaps, therefore, Ambulocetus selected environments where crocodiles were very rare or absent.

The discovery of Ambulocetus and other new basal whales has shown that they can’t all be shoehorned into an all-encompassing Protocetidae. Rather, they should be classified as several distinct groups. Pakicetus and its close relatives were given their own group, Pakicetinae, by Gingerich & Russell (1981), and this has more recently been raised to the level of ‘family’. Besides Pakicetus, Ichthyolestes pinfoldi and Nalacetus ratimitus are included. Thewissen et al. (1996) coined Ambulocetidae for Ambulocetus, and it seems that Gandakasia and Himalayacetus are also members of this group.

Remingtonocetidae was named by Kumar & Sahni (1996) for Remingtonocetus and Andrewsiphius, two very peculiar long-snouted middle Eocene whales from India and Pakistan. Andrewsiphius had previously been regarded as an odontocete on the basis of its elongate and compressed lower jaw (Sahni & Mishra 1975). However, this referral was not defensible as, like archaeocetes and unlike odontocetes, Andrewsiphius had a primitive style of tooth count, relatively deep lower jaws, and intermittent gaps between the teeth. Remingtonocetids are also odd in having a particularly long, slender snout and widely set small eyes. The most informative of them is little Kutchicetus minimus (Bajpai & Thewissen 2000), the smallest known Eocene whale*. It shows that remingtonocetids had short, stout limbs, a long, sinuous body and a remarkably long tail. I like to think that it looked like a giant desman, but that only helps if you know what a desman is.

* Though note that not all early whale experts agree that it is distinct from Remingtonocetus.

Finally, there are the middle and late Eocene protocetids. In the interests of getting this post completed and posted now, I’ll stop there. I have children to look after. Three of them (though only one is mine). More to come on basal whales in the near future.

Refs - -

Bajpai, S., Thewissen, J. G. M. 2000. A new, diminutive Eocene whale from Kachchh (Gujarat, India) and its implications for locomotor evolution of cetaceans. Current Science 79, 1478-1482.

Gingerich, P. D. & Russell, D. E. 1981. Pakicetus inachus, a new archaeocete (Mammalia, Cetacea) from the Early-Middle Eocen Kuldana Formation of Kohat (Pakistan). Contributions from the Museum of Paleontology, University of Michigan 25, 235-246.

- ., Wells, N. A., Russell, D. E. & Ibrahim Shah, S. M. 1983. Origin of whales in epicontinental remnant seas: new evidence from the Early Eocene of Pakistan. Science 220, 403-406.

Kellogg, R. 1936. A review of the Archaeoceti. Carnegie Institute of Washington Publication 482, 1-366.

Kumar, K. & Sahni, A. 1986. Remingtonocetus harudiensis, new combination, a Middle Eocene archaeocete (Mammalia, Cetacea) from western Kutch, India. Journal of Vertebrate Paleontology 6, 326-349.

Naish, D. 2004. Fossils explained 46. Ancient toothed whales. Geology Today 20 (2), 72-77.

Sahni, A. & Mishra, V. P. 1972. A new species of Protocetus (Cetacea) from the Middle Eocene of Kutch, western India. Palaeontology 15, 490-495.

Thewissen, J. G. M. 1998. Cetacean origins. Evolutionary turmoul during the invasion of the oceans. In Thewissen, J. G. M. (ed) The Emergence of Whales. Plenum Press (New York), pp. 451-464.

- . & Bajpai, S. 2001. Whale origins as a poster child for macroevolution. BioScience 51, 1017-1029.

- ., Hussain, S. T. & Arif, M. 1994. Fossil evidence for the origin of aquatic locomotion in archaeocete whales. Science 263, 210-212.

- ., Madar, S. I. & Hussain, S. T. 1996. Ambulocetus natans, an Eocene cetacean (Mammalia) from Pakistan. Courier Forschungsinstitut Senckenberg 191, 1-86.

- ., Williams, E. M., Roe, L. J. & Hussain, S. T. 2001. Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Nature 413, 277-281.

West, R. M. 1980. Middle Eocene large mammal assemblage with Tethyan affinities, Ganda Kas region, Pakistan. Palaeontology 54, 508-533.

Zimmer, C. 1998. At the Water’s Edge: Macroevolution and the Transformation of Life. Free Press (New York), pp. 290.

Tuesday, February 14, 2006

Eagle owls take over Britain

Popular mythology has it that the introduction of the 1976 Dangerous Wild Animals Act led to the mass release of numerous pet leopards, pumas and god knows what else into the British countryside, and it’s these former pets that today haunt our moors and wooded areas. That’s a subject for another time, but right now a very similar subject, but concerning a very different kind of animal, is getting lots of coverage in both the popular and zoological press: the apparent presence in the British countryside of numerous feral Eurasian eagle owls Bubo bubo. A formidable bird, it can reach 4 kg with a wingspan of 1.5 m and a length of over 70 cm. What’s this all about, and what’s the big deal anyway?

Officially, eagle owls are not British natives. Well, ok, actually they are on the ‘British list’, but then so are Magnificent frigate birds and Red-billed tropic birds (basically, any bird seen within the boundaries of the British Isles becomes a member of the ‘British list’). If they do occur here today, it’s as vagrants from continental Europe. So the apparent presence of numerous eagle owls here right now – as many as 500 pairs (some of them breeding) according to a recent TV programme – must result from accidental escape, or deliberate release. Unlike the case with British big cats, the existence of feral eagle owls is not doubted by officialdom. They are here: it’s official.

The question now is.. should we ‘keep’ them, or should we make efforts to get rid of them? Herein lies the debate. We know without doubt that Britain had eagle owls in the recent past as they’re known from palaeontological and archaeological samples. To be sure on this I checked the literature. My usual port of call on British Pleistocene vertebrates is Stuart (1974), but he doesn’t list bird taxa. However, specific British Bubo bubo specimens from the Pleistocene were described by Harrison (1979, 1987). Intriguingly, there’s a new spin on this, mentioned by Jim Giles (2006) in his Nature article on the British eagle owl problem. According to Giles, John Stewart (of University College London) has data indicating that eagle owls survived here for longer than had been thought before: ‘ornithologists had previously assumed that remains [from the past 10,000 years] came from tame eagle owls that had been imported for hunting’. Inevitably people have compared this with the recent discovery that lynxes, similarly, were around in Britain until just a thousand or so years ago. If Stewart has data indicating survival of British eagle owls right up to (say) the dawn of the agricultural revolution, he hasn’t (to my knowledge) published it. Altogether it strengthens the case for eagle owls being regarded as ‘rightful’ members of the modern British avifauna, and if we have them back here by accident.. well, that’s ok.

But should we have them back here? This is the problem. Ok, it’s all very nice, but arguments invoking the former presence of a taxon within a region are never particularly convincing because, after all, pretty much all of the Northern Hemisphere’s megafauna naturally inhabited Britain at some time within recent geological history. So while I welcome the idea of having eagle owls back in our fauna, I feel that it’s problematical, given that the reappearance of any arch predator is dependent on how intact the rest of the food chain is. It’s as if we’re hoping that we can reconstruct the country’s ancient ecosystem by building from the top down. There is lots of talk of reintroducing lynxes and wolves, but not so much talk going on about boosting the numbers and diversity of ground-dwelling slugs, rodents or passerines. Yet it follows that the trophic pyramid that will hypothetically support these arch predators must be reconstructed at its lower levels before things further up are going to fit in nicely. Rabbits. Yes, nowadays we have lots of rabbits that make up a lot of biomass, and they weren’t here when eagle owls and lynxes and wolves were truly native, so that might repair part of the problem (rabbits are not native to Britain and were introduced by the Normans). Indeed some studies find eagle owls to prefer rabbits to all other prey (Hume 1991). If this is right, then things maybe aren’t so bad after all. In fact we have too many rabbits as it is, so more predation of them is welcome.

However… other studies find eagle owls to predate mostly on birds (Bocheński et al. 1993) with some studies finding 83% of eagle owl diet (by weight) being made up by avian prey (Everett 1977). And even if this weren’t the case (and the owl population was still mostly concentrating on rabbits), there is still the fact that eagle owls are opportunistic predators that will still kill animals we don’t want them to. So while - back when eagles owls were healthily distributed natives - they could take their pick of whatever, without this being a problem, things today aren’t so rosy, and those potential prey species themselves are depleted in numbers, or even endangered or requiring protection. Indeed the RSPB has voiced concerns that eagle owls may start to impact significantly on Black grouse Tetrao tetrix, Hen harriers Circus cyaneus and other endangered species.

You see, perhaps the most interesting thing about eagle owls is that they are experts at intraguild predation: in other words, very very good at killing other raptors, and in fact at virtually eliminating them from an area. They routinely take Long-eared owl Asio otus, Goshawk Accipiter gentilis, Sparrowhawk A. nisus, Peregrine Falco peregrinus, Gyrfalcon G. rusticolus, Merlin F. columbarius and Rough-legged buzzard Buteo lagopus. More exceptional are cases of predation on Snowy owls Bubo scandiaca (note: no longer in its own genus), young White-tailed eagles Haliaeetus albicilla, and other eagle owls. Everett (1977) wrote that ‘up to 5% of [eagle owl] total prey may consist of other birds of prey and … these may make up as much as 36% of all the bird food consumed in some regions’ (p. 93). It seems that eagle owls take these birds while they are roosting, mostly (I assume) by sneaking up on them from behind. In fact, so significant are eagle owls on other raptors that some populations of Long-eared owls appear to migrate specifically because of eagle owl predation (Erritzoe & Fuller 1998).

I don’t need to tell you that, right now, Britain does not have raptor populations capable of dealing with this sort of predation. Like it or not, the presence of this species is bad news for the raptors we have. So the bottom line is that, while having eagle owls back in Britain is very nice, it is not good news for our native fauna, given the state it’s currently in, and in an ideal world, we would need to have the rest of the ecosystem restored before we could bring in the arch predators. However, all of this is academic given that it’s already too late. The eagle owls are here, and the native raptors will suffer.

The photo used above was swiped one of the digit-sight pages.

I’ll admit that today I didn’t spend much time thinking about owls. Mostly it was devoted to work on the British dinosaurs manuscript, but there is also the story of Mark Witton’s giant Thalassodromeus head and some late news on elephant skulls and the Cyclops myth. Details on these will be posted here in the near future, and while going through old files on disk I found much text that will be recycled for posts at some stage soon: Homotherium and the Piltdown cats, the lost cassowaries, Naish’s guide to Eocene whales, hybridogenesis and the necromonger frogs, and the world of worm lizards. I’d like to say a huge thank you to those of you who have made positive and supportive comments about my blog posts – it’s really appreciated.

Refs - -

Bocheński, Z., Tomek, T., Boev, Z. & Mitev, I. 1993. Patterns of bird bone fragmentary in pellets of the Tawny owl (Strix aluco) and the Eagle owl (Bubo bubo) and their taphonomic implications. Acta zool. cracov. 36, 313-328.

Erritzoe, J. & Fuller, R. 1998. Sex differences in winter distribution of Long-eared owls (Asio otus) in Denmark and neighbouring countries. Vogelwarte 40, 80-87.

Everett, M. 1977. A Natural History of Owls. Hamlyn, London.

Giles, J. 2006. Bird lovers keep sharp eye on owls. Nature 439, 127.

Harrison, C. J. O. 1979. Birds of the Cromer Forest Bed series of the East Anglian Pleistocene. Transactions of the Norfolk and Norwich Naturalists’ Society 24, 277-286.

Harrison, C. J. O. 1987. Pleistocene and prehistoric birds of south-west Britain. Proceedings of the University of Bristol Spelaeology Society 18, 81-104.

Hume, R. 1997. Owls of the World. Parkgate Books, London.

Stuart, A. J. 1974. Pleistocene history of the British vertebrate fauna. Biological Reviews 49, 225-266.

Sunday, February 12, 2006

Tortoises that drink with their noses, or: alas, goodbye Hololissa?

My renewed recent interest in the members of Testudines (and, oh no, you can’t call them Chelonia anymore…) led me, in between writing about obscure English sauropods, to dig around on a hard drive for the following text on giant tortoises from the Indian Ocean. It’s a bit dated, having first appeared on a mailing list a few years ago, but I’ve added a bit to it and tried to incorporate new information (since it was written Paul Chambers’ book on giant tortoises has been published, but I haven’t read that yet - it’s called A Sheltered Life – and Justin Gerlach’s 2004 Giant Tortoises of the Indian Ocean has appeared). The main topic here is the systematics of the giant tortoises of the western Indian Ocean - specifically those of Madagascar, the Comores, Aldabra and the Seychelles. As yet I haven’t seen much made of this information in print, nor on the internet. Comments welcome.

Recent studies, discoveries and taxonomic revisions have meant that the number of Indian Ocean tortoise species, and the genera into which these species are placed, has increased somewhat. Those previously lumped together as Geochelone gigantea are today placed in the genus Dipsochelys Bour 1982 (aka Aldabrachelys Loveridge & Williams 1957, which has been argued by some to be the correct generic name for these animals, despite Bour's contention that it is unavailable), and while this idea is widely accepted, exactly how many species constitute the assemblage is more controversial, as we’ll see. Morphologically, these are very interesting tortoises, with a particularly short supraoccipital crest and a notably deep, narrow snout with unusual nasal passages. Normally in tortoises, the channel connecting the external naris to the olfactory chamber is short and sub-horizontal, and the olfactory chamber is also short, and open to the connecting channel. In Dipsochelys, however, the external naris is vertically elongated and the nasal passage is long and ascends steeply as it approaches the olfactory chamber. The chamber itself is then quite long, and demarcated from the nasal passage by a distinct medially projecting vertical ridge. What is this all about? It seems that these are specialisations allowing Dipsochelys to drink… through its nostrils. As reported by Nick Arnold (1979), I. R. Swingland found that Dipsochelys sometimes drinks through its nose, and that these unusual features assist it in doing this. The narrow, pointed snout is better for getting the nostrils into small puddles and other bodies, and the vertical ridge at the front of the olfactory chamber seems to anchor a soft-tissue valve that prevents water from being snarfed deep into the olfactory chamber (as would happen with any normal tortoise, were it to try drinking like this). This all makes sense in a group of tortoises that have to make a living in arid environments where standing water is relatively rare. Incidentally, since this was written, Gerlach (2004a) has published the paper ‘The complex nasal structure of Dipsochelys and its identification as a true Jacobson's organ’. That certainly sounds relevant to this story, but I haven’t yet seen it.

But while, as noted above, most workers – until recently – had regarded these tortoises as representing a single species, things have now become much more complicated. In 1982, Roger Bour proposed that four museum specimens from the Seychelles represented a new species which he named D. arnoldi (Bour 1982). This discovery prompted Gerlach & Canning (1998a, b) to produce a taxonomic revision of Dipsochelys. They now suggested the presence of six species: D. dussumieri from Aldabra, D. hololissa and D. arnoldi from the Seychelles, D. daudinii (probably) from the Seychelles, and D. abrupta and D. grandidieri from Madagascar. Their distinction was also supported in a study on shell morphology by Gerlach (1999) who found notable differences in how the neural bones were arranged (these are the bones that, together with the nuchal, suprapygals and pygal, form the midline of the shell). D. arnoldi was reported to be the most divergent, with a special saddle-backed morphology allowing it to be a specialist high-browser.

Excepting D. arnoldi Bour, 1982, all of these names are old, so the species recognised by Gerlach & Canning (1998a, b) have been resurrected from synonymy and are not 'new' species in the strictest sense of the term. D. abrupta was first coined [as Geochelone abrupta] by Grandidier (1868), D. hololissa [as G. hololissa] by Gunther (1877), D. daudinii [as G. daudinii] by Dumeril & Bibron (1835), D. dussumieri [as G. dussumieri] by Gray (1831), and D. grandidieri [as G. grandidieri] by Vaillant (1885). Until recently all of these Indian Ocean species, excepting the Aldabran D. dussumieri, were thought to be extinct. As has been reasonably well reported however, both Bour and Gerlach & Canning reported the discovery of live giant tortoises which appeared to belong to some of the Dipsochelys taxa they identified. Gerlach & Canning explained how morphological examination and application of randomly amplified polymorphic DNA analysis (RAPDs) supported the idea that both D. arnoldi and D. hololissa were still extant in captivity. Alleged D. arnoldi and D. hololissa specimens have now been identified at zoos and wildlife parks in Mauritius, the Seychelles, Kansas, Michigan, Hawaii and the UK. This is pretty exciting stuff and has prompted a major captive breeding program. There is tons of stuff about it on the internet if you want more info.

Alarm bells concerning the status of these supposed rediscovered taxa began to ring however when Palkovacs et al. (2002) could not find any differences among the purported living Dipsochelys species in the examined regions of mtDNA, and Palkovacs et al. (2003) later produced another study shedding further light on this issue (I should note that Justin Gerlach is on the authorship of both of these papers, so don’t go thinking that he’s in disagreement with this work). By studying the mtDNA of 55 captive Dipsochelys tortoises (including seven specimens identified on morphological criteria as D. arnoldi and ten identified as D. hololissa), they found that there is no evidence for genetic differentiation between extant D. dussumieri individuals and alleged D. arnoldi and D. hololissa individuals (the initial result of the RAPD analysis reported by Gerlach & Canning was put down to shortcomings with this method and the preliminary nature of the study).

Instead, the results indicate the survival of just a single lineage of Indian Ocean giant tortoises. This contrasts strongly with results obtained from other giant tortoise island radiations (Galapagos tortoises and extinct Mascarene tortoises) where genetic variation between both the populations of different islands, and populations living on the same islands, is high. Given that genetic variation among surviving Dipsochelys individuals is so low - and not consistent with the survival of three species - what does this mean? Palkovacs et al. (2003) offered three possibilities.

The first is that D. arnoldi and D. hololissa are extinct and D. dussumieri is the only extant Dipsochelys after all. This would mean that the morphological criteria on which extant supposed D. arnoldi and D. hololissa have been identified are utterly unreliable: an idea which matches suggestions that 'carapace morphology is sensitive to environmental conditions and that captivity can result in aberrant morphologies' (Palkovacs et al. 2003, p. 1409; see also Gerlach 2004b). The second possibility is that D. arnoldi and D. hololissa never existed as distinct taxa at all, and the differentiation of these species from D. dussumieri was and is unwarranted. As Palkovacs et al. (2003) noted, this would only be likely if Aldabran and Seychelles tortoises had not had the opportunity to diverge genetically: therefore, the populations must either have diverged very recently, or there must have been regular and substantial gene flow between Aldabra and the Seychelles. The latter option appears unlikely - it is hard to imagine that many tortoises swimming to and fro between the islands (and, yes, when at sea giant tortoises really do swim). Rapid divergence of phenotype but not of genotype is theoretically possible, but given the genetic closeness of the sampled individuals (and this assumes that the extant Giant tortoises identified as D. arnoldi and D. hololissa really are remnants of the same populations as those given these names but based on old material), should they be recognised as species separate from D. dussumieri? I suppose this would be down to personal taste - i.e., whether splitting or lumping is adopted.

The third possibility is that hybridisation between Aldabran and Seychelles tortoises has obscured the true genetic distinctiveness of the D. arnoldi and D. hololissa individuals. In other words, D. dussumieri individuals introduced to the Seychelles may conceivably have swamped the mtDNA haplotypes of D. arnoldi and D. hololissa, even though the unique Seychelles morphology could persist. This idea can be discounted because the suspected hybrids would reveal distinctive microsatellite alleles not occurring in non-hybrid D. dussumieri, and they don't.

In conclusion then, Palkovacs et al. (2003) showed that there almost certainly aren't extant individuals of D. arnoldi and D. hololissa. So, assuming that the museum type material of D. arnoldi and D. hololissa really does represent taxa distinct from D. dussumieri, does this mean that all the identifications of living tortoises as representatives of D. arnoldi and D. hololissa have been incorrect? Or does it mean that D. arnoldi and D. hololissa were never good species at all, but that they just represent ecomorphs of D. dussumieri?

Genetic data from fossils would help clear up the picture, as would convincing evidence that the living individuals identified as D. arnoldi and D. hololissa really do represent exactly the same thing as the museum specimens that bear these names. Needless to say these conclusions put doubt on the aims of the captive breeding program, and as yet I haven't heard of a response from any of the people involved (though, as noted above, I haven’t seen Gerlach’s 2004 book on Indian Ocean tortoises, plus a few other recent papers of his). If anyone has new information I'd be very interested. Err, back to those sauropods…

The photo (of D. dussumieri) was borrowed from the iguana site.

PS - for the latest news on Tetrapod Zoology do go here.

Refs - -

Arnold, E. N. 1979. Indian Ocean giant tortoises: their systematics and island adaptations. Philosophical Transactions of the Royal Society of London B 286, 127-145.

Bour, R. 1982. Contribution a la connaissance des tortues terrestres des Seychelles: definition du genre endemique et description d'une nouvelle probablement originaire des iles granitiques et au bord de l'extinction. Comptes Rendu de l'Academie des Sciences, Serie III, Sciences de la vie, Paris 295, 117-122.

Gerlach, J. 1999. Distinctive neural bones in Dipsochelys giant tortoises: structural and taxonomic characters. Journal of Morphology 240, 33-37.

- . 2004a. The complex nasal structure of Dipsochelys and its identification as a true Jacobson's organ. Herpetolological Journal 15, 15-20.

- 2004b. Effects of diet on the systematic utility of the tortoise carapace. African Journal of Herpetology 53, 77-85.

- . & Canning, K. L. 1998a. Taxonomy of Indian Ocean tortoises (Dipsochelys). Chelonian Conservation and Biology 3, 3-19.

- . & Canning, K. L. 1998b. Identification of Seychelles giant tortoises. Linnaeus fund research report. Chelonian Conservation and Biology 3, 133-135.

Palkovacs, E. P., Gerlach, J. & Caccone, A. 2002. The evolutionary origin of Indian Ocean tortoises (Dipsochelys). Molecular Phylogenetics and Evolution 24, 216-227.

- ., Marschner, M., Ciofi, C., Gerlach, J. & Caccone, A. 2003. Are the native giant tortoises from the Seychelles really extinct? A genetic perspective based on mtDNA and microsatellite data. Molecular Ecology 12, 1403-1413.