Tetrapod Zoology

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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?

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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.

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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).

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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).

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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.

Comments

  1. #1 Will Baird
    April 12, 2007

    Congratz, Darren!

  2. #2 J-Dog
    April 12, 2007

    You said: …”Britain now has rebbachisaurids (the oldest known, bizarrely), “…

    Not so bizarre. You ARE the mother country after all.

    But seriously, excellent post, thanks for all the work and lovely details.

  3. #3 Joseph j7uy5
    April 12, 2007

    This publication sounds like a wonderful accomplishment. Congratulations.

  4. #4 Mickey Mortimer
    April 13, 2007

    “A few new opinions are published on Stonefield Slate theropods,”

    From the paper- “Straight femora from Stonesfield, possessing a robust anterolateral ridge connected to the anterior trochanter, appear to belong to a non-tetanuran theropod (Day & Barrett 2004), possibly an abelisauroid.”

    Sounds so familiar…. ;)
    From
    http://dml.cmnh.org/2005Jan/msg00386.html

    “So what is femoral morphotype A? The anteromedially directed head eliminates derived eustreptospondylines and avetheropods. The aliform anterior trochanter eliminates coelophysoids, non-abelisaur ceratosaurs, and non-megalosauroid+avetheropod tetanurines. The proximal extent of the trochanter eliminates the first two groups as well. The absent extensor groove eliminates tetanurines. A groove on the lateral condyle is only known in coelophysoids and ceratosaurs. So my best guess is that this taxon is an abelisaur. Interestingly, Masiakasaurus is described as having a triangular femoral cross section proximally much like in morphotype A.”

    Nice reconstruction of Eotyrannus though.

  5. #5 Jeff Wilson
    April 13, 2007

    Congratulations on your new paper, Darren!

    As I buzzed through your post, I halted at your discussion of obsolescent (or “obsolete” as you call them) characters. They don’t come up very often in discussions for whatever reason but they are certainly relevant when we are talking about early holotypes – so it is great you dragged it out of obscurity. In the spirit of venturing into something even more arcane, I thought I would chime in to clarify our (Paul U. and my) intent in using the word “obsolescent” in lieu of the much more obvious word “obsolete” in the character context. You are correct that “obsolescent” refers to something that is in the process becoming obsolete, whereas “obsolete” refers to the finished product. Paul and I wanted to describe a process by which characters drift from their original, envisioned home towards ever more remote places on the tree. In other words, character distributions change over time because new fossils are found and new interpretations are made that change them, if ever so slightly. We wanted to avoid the word “obsolete” because to us it gave the sense that the process stops and characters stay fixed. I realize that you and others may be looking at this from the perspective of a particular clade of interest, e.g., character 1 is now “obsolete” for X clade and so on. Although this is slightly different than what we had in mind, I don’t have a problem with that usage – it is technically correct – but if you use it in this sense it requires a “clade X” and becomes more or less synonymous with the word “symplesiomorphic”.

    A final, unrelated comment . . . while I am delighted that there are rebbachisaurid teeth in the UK (where are the skeletons?), I don’t think they are the oldest record. There are coeval or earlier records of a Barremian-Aptian rebbachisaurid from Spain (Pereda-Suberbiola 2003) and possibly material from the Hauterivian-Barremian of Croatia (Dalla Vecchia 1998).

    JAW

  6. #6 David Marjanovi?
    April 13, 2007

    Ok, it’s not.

    ROTFL! You really know how to write! :-D

    as obsolescent is an adjective

    So is “obsolete”.

    Or actually, both are participles rather than adjectives, but that often doesn’t matter.

  7. #7 bigcitylib
    April 13, 2007

    I thought the correct term was “scrappy”.

  8. #8 Zach Miller
    April 13, 2007

    Fragmentary remains in England? HA! You guys are LUCKY. Here in Alaska, we get actual scraps. Our dinosaurs are eroding out of a riverbank canyon, and many are probably washed away after rolling down the hill, into the river, and lost forever. Yeah, I guess we’ve got “Lizzie,” North America’s oldest known hadrosaur, but guess what? All relevant parts of the skeleton for identification (skull, pelvis) are unknown. Otherwise, we have teeth and bits and pieces of axial skeleton.
    However, awesome post, sir. I’d love to know more about the new Scelidosaurus find, myself. Has that critter’s phylogenetic position been solidified yet?

  9. #9 Christopher Collinson
    April 13, 2007

    Darren, do you see any of the forty odd dollars it costs to download the pdf from Ingenta?

    [added by Darren: ye-es.. which would be why I offered to send the pdf to anyone who asked for it]

  10. #10 Christopher Collinson
    April 13, 2007

    No, I ment does any of it make its way back to your wallet?

  11. #11 Darren Naish
    April 14, 2007

    Many thanks to all for their comments.

    Jeff, thanks for your clarification on use of the term ‘obsolescent’, that’s helpful. On the oldest rebbachisaurids, the Burgos material described by Pereda Suberbiola et al. (2003) is late Barremian-early Aptian and thus slightly younger than the Wessex Formation material (the exposed Wessex represents the early, middle and early late Barremian, with most of the late Barremian being unexposed. The rebbachisaurid teeth actually came from Sudmoor Point and are thus low [viz, early or middle Barremian] in the succession). Histriasaurus is indeed older (it’s from the Hauterivian/Barremian of Croatia; Dalla Vecchia 1998) and I regret not crediting it (of course, we’re not yet sure that it really is a rebbachisaurid, but you could say the same for the Isle of Wight material).

    It seems odd that Britain contains oldest (or nearly oldest) records for so many dinosaur clades, but what this means and whether it’s even worthy of ‘bigging up’ depends on your perspective. At some stage we should expect the discovery of rebbachisaurids that pre-date the Barremian and even the Hauterivian anyway, and it will be interesting wherever they come from.

    Chris: sorry, I misunderstood. No, none of that money comes back to the authors. Little appreciated outside of academia is that no money is ever made from publishing peer-reviewed literature. If anything, it costs you money.

  12. #12 David Marjanovi?
    April 14, 2007

    “Page charges”.

    And colour figures cost extra. They tend to be stunningly expensive. Grants are not for just making research, but for publishing it, too.

  13. #13 Anthony Docimo
    April 14, 2007

    Congrats on your publication…and sorry to hear about how much of it was removed.

    As to the rich fossil diversity of Britain, well, at least we can rest easy that they can’t cancel Primeval on us anytime soon. :D

    have nice days & be well.

  14. #14 Denver Fowler
    April 15, 2007

    Hmmm… As the person who found and ID’d the specimens (after some deliberations); the rebbachisaur teeth did not come from Sudmoor point, although i did encounter one rebbachisaur tooth from the conglomerate exposed just brook-side of Sudmoor Point, it did not survive extraction (it was the smallest one I have found, and was rather smaller than the other 3, [now 4, incidentally] that were figured in the book).

    All four specimens have come from the conglomerates exposed in Brighstone bay. And yes, there are postcrania known.

    Denver.

  15. #15 Darren Naish
    April 15, 2007

    Denver: why do Naish & Martill (2001, p. 236) say that the teeth came from Sudmoor Point? This information comes from the IWCMS records (see the Appendix of Dinosaurs of the Isle of Wight, p. 421)… and where did the IWCMS get this information from? That’s meant to be an honest question, not an accusation. Thanks for commenting. Please get your rebbachisaurid postcrania into press, that is an order.

    Ref – -

    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.

  16. #16 Denver
    April 16, 2007

    No idea why it says sudmoor… I explained in detail where they came from. Two of them even came from the same block of conglomerate. I did mention the Sudmoor specimen in my account, so maybe that is part of the confusion. It’s always possible I used the wrong bed name I guess, although that seems unlikely. My dad found one of the specimens. The newest specimen (June 2005, found the evening of David’s funeral, same site as the others, but from a loose block in the sea) shows some interesting new features though… that I shall leave to the paper.

    D.

  17. #17 Martin Munt
    April 17, 2007

    Hello Darren,

    The museum would appreciate a pdf of the paper so we can update our type, figured and cited catalogue. I will also check our records with respect to the sauropod teeth and make adjustments to our records accordingly.

    best wishes
    Martin (IWCMS)

  18. #18 Sarda Sahney
    April 18, 2007

    Congratulations on the paper, I really appreciate papers like this that review and compile other work while providing a greater context. It is excellent and thorough!

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