Yesterday the most remarkable thing happened. No, I have not been handed new DNA work on the Dufftown rabbit-headed cat, nor has the rest of Yaverlandia been found. An articulated azhdarchid has not been discovered on a Cretaceous savannah ashfield, nor have the islands of the SW Pacific yielded an assortment of ten new cursorial, durophagous and scansorial mekosuchine crocodiles. No, it’s something far, far more significant than any of those things…
Ok, it’s not. Regular readers will be aware of one of the biggest proverbial thorns in my side: that bloody review paper on the British dinosaur record. I forget when it was, long long ago in the dim and distant past, when Dave Martill and I were asked to contribute a special paper for the bicentennial review issue of the Journal of the Geological Society, London, but I do know that I was discussing the slow and tedious progress of this paper as of January 2006, and in January 2007 was still mentioning it as a project that had ‘yet to come to fruition’. Well, at last, the British dinosaurs paper is out. It has the snappy title ‘Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia’. It is published as part of a special issue that celebrates 200 years of The Geological Society of London: you can read the abstract (and perhaps access the pdf) here [alternatively, email me for the pdf]. Believe it or don’t, this the first comprehensive review of the British dinosaur fauna since William Elgin Swinton (1900-1994) provided an annotated list in 1934 (though, having said that, Naish & Martill 2007 is but part I of the review and part II is yet to appear). Anyway… so, was it worth the wait?
As some of us point out on way too many occasions, Britain has a rich and diverse dinosaur fauna. It’s not true that all British dinosaurs are crappy and based only on fragmentary remains (look at Hypsilophodon, Cumnoria, Mantellisaurus, Baryonyx and Neovenator), but it is true that most of them are. At least some palaeontologists have an intense dislike of crappy, fragmentary fossils, and at least some decry the fact that palaeontologists are so often imagined as sad uber-geeks who get excited when the opportunity to describe an isolated toe-bone or an incomplete isolated vertebral centrum comes along. British dinosaur taxa are indeed generally based on poor remains that lack autapomorphies or are, for want of a better term, ‘crappy’. In fact, of 108 British taxa (excluding nominda nuda and objective synonyms), c. 54% are nomina dubia (Naish & Martill 2007). However, we need to see this in perspective [accompanying Luis Rey Baryonyx from Luis' website].
Firstly, the genesis of dinosaur science in Britain means that the early workers were erecting species based on features that – unbeknownst to them – were not unique, but in fact of far more widespread distribution. Wilson & Upchurch (2003) termed these features obsolete characters*, and it’s an artefact of history that Britain is littered with so many taxa based on these. Secondly, modern palaeontology has evolved a rather unfair trigger-happy approach to incomplete specimens. If a fossil lacks diagnostic characters (= autapomorphies) it is automatically labeled a nomen dubium and then assumed not to refer to a taxonomic entity worthy of recognition at the species level. In fact, a significant percentage of specimens that lack autapomorphies almost certainly do so because of poor preservation, not because they fail to represent species that actually existed, and a great many nomina dubia surely must represent taxa that simply remain poorly known.
* Actually, they termed them ‘obsolescent characters’, which is arguably incorrect as obsolescent is an adjective, and the characters concerned are not ‘becoming obsolete’, they are obsolete.
Thirdly, like it or not, many fossil species are unavoidably represented by very fragmentary remains, and it is not fair and not useful to think that such remains are worthless. While some workers have argued that ‘the practice of naming genera on such a slim basis is a highly undesirable one, greatly to be discouraged’ (Dodson 1996, p. 240) ‘naming taxa, even those based on fragmentary remains, can be a useful exercise simply because named taxa are incorporated into large-scale studies of systematics and diversity. Unnamed taxa, even those thought to represent new species, generally are not’ (Naish & Martill 2007, p. 506). I’m certainly not saying that we should to return to the days when uninformative scraps were named as new species; rather, that isolated remains should be named if, indeed, they appear to represent something new.
These points and what they might mean for dinosaur diversity are discussed further in the paper, and I’ll have more to say on these issues in the near future when another paper on British dinosaurs is published. For previous discussion of some of these points see Cryptic dinosaur diversity.
In order to fit the article into the allotted issue, it had to be pruned hard. In fact about half of the words were axed: tons of additional historical, biographical, geographical and stratigraphical data was deleted. We lost all the data on the discoveries and debates of the 19th century, our extensive biographic discussion of renowned ophthalmologist John Whittaker Hulke (1830-1895) was deleted, and an entire section on alleged Lower and Middle Triassic dinosaurs, and my hilarious quips on the upside-down, wrong-sided theropod tibia from the Upper Broadford Beds Formation of the Isle of Skye (Benton et al. 1995) are no more. Oh yes, and all my beautiful little cladograms were axed (of which one is shown in the adjacent image). However, I suppose I’ll be able to recycle most of this material, maybe for the blog
David Sole’s awesome new Scelidosaurus specimen is figured in the literature for the first time. It currently belongs to a private collection, so you could argue that we shouldn’t have figured it… I’ll avoid that can of worms for the time being. The specimen is the most complete scelidosaur yet reported, with a complete skull, in-situ armour and everything. If you really like thyreophorans you might do yourself some sort of soft-tissue accident while looking at it (the actual specimen, not a picture of it). Short curving horns are on the squamosals and sharply hooked osteoderms are arranged in rows down the sides of the limbs. These features are not present in other scelidosaur specimens; presumably this is evidence of dimorphism, but the possibility that this is actually a new taxon also exists. The image of the specimen shown below is borrowed from here (as is the image at the top of the article).
Mark Evans very kindly provided a brand new skeletal reconstruction of Cetiosaurus, based on the excellent Rutland or Great Casterton specimen described by Upchurch & Martin (2002). We were also able to publish the photographic montage of the Cetiosauriscus stewarti holotype, a first I think (the montage was produced by Jeff Liston and has appeared previously on conference posters that Jeff has produced on his historical Oxford Clay work). My skeletal reconstruction and partial cranial reconstruction of Eotyrannus are also published for the first time (one day that monograph will be published… one day).
The article itself includes a systematic review of Britain’s basal dinosaurs, sauropodomorphs and theropods. Britain now has rebbachisaurids (the oldest known, bizarrely), a mamenchisaurid (apparently), definitive diplodocids (and not just diplodocoids – and no I’m not referring to the Isle of Wight chevron), good brachiosaurids (as in, taxa very close to Brachiosaurus) and some titanosaurs [adjacent image shows me with the 'Angloposeidon' vert: go here for full story]. The new name for Thecodontosaurus caducus, Pantydraco (sorry, not kidding: Pantydraco), came out too late for inclusion (Galton et al. 2007). We also failed to include a mention of Turiasauria: this group might be relevant as there are a few British teeth that might belong to it.
A few new opinions are published on Stonefield Slate theropods, some of which may be superseded by the ongoing work of Roger Benson, Paul Barrett, Julia Day and colleagues, and a case is made that Valdoraptor is diagnostic and nothing to do with Eotyrannus or Neovenator, as was proposed in one recent review. And there’s a lot more that could be said, but that would sort of make the paper redundant wouldn’t it. Oh yes, Yaverlandia. Ye-es… Yaverlandia. Mu-mu-mu. Now all I have to do is wait for part II to appear…
I was supposed to be at an outdoor re-wilding conference today.
UPDATE (added 9-7-2007): I have just discovered that the supplementary info to Naish & Martill (2007), including a taxonomic listing of all British dinosaurs and locality maps, is available here.
Refs – -
Benton, M. J., Martill, D. M. & Taylor, M. A. 1995. The first Lower Jurassic dinosaur from Scotland: limb bone of a ceratosaur theropod from Skye. Scottish Journal of Geology 31, 177-182.
Dodson, P. 1996. The Horned Dinosaurs. Princeton University Press (Princeton, NJ).
Galton, P. M., Yates, A. M. & Kermack, D. 2007. Pantydraco n. gen. for Thecodontosaurus caducus YATES, 2003, a basal sauropodomorph dinosaur from the Upper Triassic or Lower Jurassic of South Wales, UK. Neues Jahrbuch fur Geologie und Palaontologie Abhandlungen 243, 119-125.
Naish, D. & Martill, D. M. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London 164, 493-510.
Upchurch, P. & Martin, J. 2002. The Rutland Cetiosaurus: the anatomy and relationships of a Middle Jurassic British sauropod dinosaur. Palaeontology 45, 1049-1074.
Wilson, J. A. & Upchurch, P. 2003. A revision of Titanosaurus Lydekker (Dinosauria – Sauropoda), the first dinosaur genus with a ‘Gondwanan’ distribution. Journal of Systematic Palaeontology 1, 125-160.