Tetrapod Zoology

i-6d1cc8e50d2ca1c9725e9b7c4668f5c8-sarco + istio.jpg

Another one of those projects too-long-in-gestation has finally appeared and, unlike the others (e.g., the much-delayed British dinosaurs article), it’s one that I haven’t previously mentioned on the blog (I think). For the last couple of years I’ve been working, on the side as it were, with University of Bristol’s Barbara Sánchez-Hernández and Mike Benton on the fossil vertebrates from the Galve region of Teruel Province, NE Spain. This is a really rich site, best known for its sauropods and mammals, and it’s been the focus of much research since the 1950s. Our new paper – a large synthesis of the fauna, published in Palaeogeography, Palaeoclimatology, Palaeoecology – was made available last week (Sánchez-Hernández et al. 2007), and provides much new data on the distribution of such creatures as istiodactylid pterosaurs, spinosaurid theropods, and heterodontosaurids. If you like Cretaceous tetrapods, it’s all very, very exciting…

Before I start, let’s get some announcements out of the way. At the top of the list is the fact that one of my biggest friends, Matt Wedel (aka Dr Vector), filed his Phd thesis on Friday. For Matt’s singular take on this go here. Congrats Matt – though I assume he’s not around, and is hopefully still living it up on some sort of Berkeleyesque bar crawl. Wa-hey: with his pesky thesis out of the way, Matt will no doubt finally put the finishing touches to those ‘Angloposeidon’ and saurischian pneumaticity papers we’ve been working on for the past few years :) In other stuff, I recently added a load of new info to the biographical section of the site, and have added links to the free pdfs that are available [note that the Naish & Martill J. Geol. Soc. paper is freely available to all]. I’ve also (thanks to Mark North) just uploaded a youtube video of me holding a slow-worm to the Beasts of Portland article, though it’s not particularly exciting I’m afraid to say.

The Mesozoic sediments in the Galve region span the Upper Jurassic-Lower Cretaceous transition, with five formations ranging in age from Tithonian to Aptian*. This range in age means that, potentially, we see a change in the fauna from an Upper Jurassic assemblage to a Lower/mid Cretaceous one similar in flavour to the Wealden assemblages of southern England. The vertebrate fauna at Galve is really interesting for a host of reasons: this article will be a quick run-down of some of the highlights, and for the full details you’ll need to see the paper. It’s available on the web here, but as always feel free to email me if you want the pdf. There are fish, lissamphibians, lizards and turtles at Galve, but I won’t be covering those here. There is also a good assemblage of mammals, including diverse multituberculates and a couple of dryolestoids and spalacotheriids. A large number of Spanish researchers have been working actively at Galve for some time, including José Ignacio Canudo, José Luis Barco, Gloria Cuenca-Bescós and José Ignacio Ruiz-Omeñaca: a great deal of further information, and many free pdfs, are available at their aragosaurus.com site.

* These are the Higueruelas Formation (Tithonian), Villar del Arzobispo Formation (upper Tithonian-middle Berriasian), El Castellar Formation (upper Hauterivian), Camarillas Formation (lower Barremian) and Artoles Formation (upper Barremian-lower Aptian).

i-f83c6f0c12e3c7f7795d82ad298cef49-Sereno & Sarcosuchus.JPG

As we’ll see, it’s frustrating that some of the most interesting groups present in the Galve deposits are represented only by fragmentary remains, or even just by trackways. With regard to the latter, an outcrop of the Villar del Arzobispo Formation at El Cantalar preserves a trackway produced by a crocodyliform that must have been about 12 m long. No typo: 12 m. Mesozoic crocodyliforms of this size are known from the Upper Cretaceous of North America (the alligatoroid Deinosuchus) and the mid Cretaceous of northern Africa (the pholidosaurid Sarcosuchus and the unique Stomatosuchus), but that’s about it, as large crocodyliforms were very rare in the Mesozoic. Deinosuchus, Sarcosuchus and Stomatosuchus are, almost certainly, too young to be anything to do with the animal that made the El Cantalar trackway, and we remain unsure as to exactly what sort of animal produced it. How incredibly cool: the thought that there is a 12 m long crocodyliform in the fossil record of Upper Jurassic/Lower Cretaceous Spain is pretty exciting. Can someone go out and find it please? Teeth, osteoderms and bones belonging to atoposaurids, Bernissartia and possibly pholidosaurids and teleosaurids are all known from Galve, so – giant unknowns or not – the region had a diverse croc fauna (Sánchez-Hernández et al. 2007).

i-4b46f757394a7afeb6e6c15505ec52c4-Deinosuchus.jpg

To give you some idea how big a 12-m-long crocodyliform might be, above is Paul Sereno with Sarcosuchus (from here), and in the adjacent picture is a high-walking Deinosuchus to scale with a person (could Deinosuchus really do a high walk? I don’t know, but it might be doubtful). The latter picture is borrowed from Tracy Ford’s dinohunter site, thanks Tracy. The image at the top combines a Sarcosuchus skull, also by Tracy, with a life restoration of an istiodactylid (produced by me). The animals are only loosely drawn to scale.

Pterosaurs are also present at Galve: the remains aren’t great (predominantly consisting of teeth), but there is enough identifiable material for us to be able to demonstrate the presence of, again, quite a diverse assemblage (Sánchez-Hernández et al. 2007). We’re talking ornithocheirids and dsungaripterids, possible gnathosaurines and, most interestingly (for me), istiodactylids. Istiodactylids are an odd and poorly known pterosaur group that were long known only for Istiodactylus latidens from the Vectis Formation of the Isle of Wight. They’ve recently turned up in the Lower Cretaceous of China, and isolated teeth now show that they were present in the Wessex Formation (the best-known dinosaur-bearing Lower Cretaceous unit on the Isle of Wight), and at Galve. The istiodactylid skull is highly unusual, being broad-snouted and with subtriangular teeth arranged in an arcade at the jaw tips. For discussion on this, do go see Mark Witton’s essay on them here. I nicked the illustration below (produced by Mark) from the same place.

i-906039a8b1dad4d112fce0c19c36fa80-Istiodactylids.jpg

Istiodactylus is one of those Mesozoic tetrapods that has a particularly convoluted and silly nomenclatural history: I won’t review this here (see Naish et al. 2001 and Howse et al. 2001), but this is the pterosaur traditionally labelled Ornithodesmus (the ‘real’ Ornithodesmus turned out to be a maniraptoran theropod [Howse & Milner 1993, Norell & Makovicky 1997, Naish & Martill 2007], presently known only from sacral vertebrae). When it was realised that Ornithodesmus was a theropod, a new name was needed for the pterosaur. It went around for a while being referred to as ‘Ornithodesmus‘ or as ‘the pterosaur formerly known as Ornithodesmus‘, and not until 2001 did Stafford Howse and colleagues publish the new name Istiodactylus. Meaning ‘sail wing’, it’s fairly euphonious I suppose, but such a remarkable beast could surely have been given a rather more descriptive name (let’s face it: ‘sail wing’ could apply to just about any pterosaur). Other missed opportunities of this sort include [sorry Dave Martill] Arthurdactylus (another pterosaur) and Irritator (a spinosaurid) and every dinosaur that gets named place-o-saurus, regardless of how remarkable it is anatomically. Really cool, neat and clever names include such wonders as Eotyrannus, Mirischia and Xe- – oops, sorry.

Anyway, I was instrumental in the naming of Istiodactylus: I don’t mean that I had anything to do with the derivation of the name itself, but I was responsible for getting Stafford Howse and Andrew Milner involved in the pterosaur chapter of Dinosaurs of the Isle of Wight, the book where the name was first published.

More in part II: the theropods, the sauropods and the ornithischians. Ornithischians? Surely I jest..

Refs – -

Howse, S. C. B. & Milner, A. R. 1993. Ornithodesmus – a maniraptoran theropod dinosaur from the Lower Cretaceous of the Isle of Wight, England. Palaeontology 36, 425-37.

- ., Milner, A. R. & Martill, D. M. 2001. Pterosaurs. In Martill, D. M. & Naish, D. (eds) Dinosaurs of the Isle of Wight. The Palaeontological Association (London), pp. 324-335.

Naish, D., Hutt, S. & Martill, D. M. 2001. Saurischian dinosaurs 2: Theropods. In Martill, D. M. & Naish, D. (eds) Dinosaurs of the Isle of Wight. The Palaeontological Association (London), pp. 242-309.

- . & 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.

Norell, M. A. & Makovicky, P. J. 1997. Important features of the dromaeosaur skeleton: information from a new specimen. American Museum Novitates 3215, 1-28.

Sánchez-Hernández, B., Benton, M. J. & Naish, D. 2007. Dinosaurs and other fossil vertebrates from the Late Jurassic and Early Cretaceous of the Galve area, NE Spain. Palaeogeography, Palaeoclimatology, Palaeoecology 249, 180-215.

Comments

  1. #1 Mark Witton
    May 20, 2007

    Hey Darren,

    Thanks for the picture and link. As so often happens with these things, my istiodactylid picture is one of my least favourites: I have a history of trying to draw them and failing miserably. Still, well done on finally getting this stuff published: a 12 m crocodile in deposits of this age and setting is pretty exciting. I’m already planning trips to the Wessex Formation to find Macropompeysuchus (not really).

    Mark

  2. #2 Tommy Tyrberg
    May 20, 2007

    An interesting question: if Deinosuchus or the Galve trackmaker *could* high walk, what might their maximum speed have been?
    I remember the first time I saw crocodiles high-walking (or rather high-running). I came upon two largish african crocodiles unexpectedly on a riverbank in Kenya whereupon they suddenly sprouted long legs and galloped down into the river at an absolutely incredible speed. Since I had regarded crocodiles as rather sluggish creatures it was sobering to realize that you have absolutely no chance of outrunning a crocodile that is large enough to be dangerous.

  3. #3 Denver
    May 21, 2007

    Hey Darren,

    Are the figures in the print edition so fuzzy as the PDF (from the PPP website). Do you have a super-quality PDF as a coauthor? Specifically I’m looking for a good pic of the pterosaur teeth in fig.5.

    cheers,

    Denver.

  4. #4 Richard Butler
    May 21, 2007

    Darren; surely the ornithischians deserve a post (or perhaps three) by themselves?

  5. #5 Dr Vector
    May 21, 2007

    Thanks for the shout-out, and congratulations on the paper. Stand by to restart the engine on the Naish-Wedel Trans-Atlantic Juggernaut of Pneumatic Doom…

    Next topic: is there any evidence or informed speculation about whether these 10-meter-plus crocs were less terrestrial than their smaller cousins?

    And looking forward to the sauropods, is it possible that part II (or XVII; I’m patient) will include an explanation of the Galvesaurus/Galveosaurus situation? Also a mnemonic to help us remember which name is valid, please. :-)

  6. #6 Dave Godfrey
    May 21, 2007

    Great post, I’d wondered what had happenned to Ornithodesmus like Criorhynchus it seemed to have vanished without much explanation between Wellenhofer’s encyclopedia, and Unwin’s recent book. (Criorhynchus seems a nicer name than i>Ornithocheirus to me).

  7. #7 Dave Hone
    May 22, 2007

    I’ve been bitching about crappy names for years, I’m glad I’m not the only one. Name-o-saurus, place-o-saurus, something-raptor, eo-something arrrgh! Whatever happened to great names that *meant* something. Fight the good fight!

  8. #8 Darren Naish
    May 22, 2007

    What’s wrong with eo-something? Sob.

  9. #9 Sordes
    May 22, 2007

    It would be really interesting to know how this giant crocodile looked, given the wide range of shapes in the skulls of prehistoric monster-crocs. I personally prefer those giant crocodilians like Purussaurus, Mourasuchus, Ramphosuchus or Gavialosuchus which are from the post-cretaceous times, perhaps you will once find the time to blog about them (but actually I am more interested in the promised meiolaniid-post).
    BTW, perhaps you have noticed that I have now my own blog. It looks still a bit boring and has only a few posts untill now, but this will surely change over time.

  10. #10 Dave Hone
    May 23, 2007

    OK Eotyrannus survived ;-) but I get very annoyed with Pro-taxon and Eo-taxon that a few years down the line somewhat inevitably turn out to be completely unrelated to the taxon they were named for (Procompsognathus, Protoaves etc.).

    Its confusing for other researchers, let alone the general public. And even if the identification is correct (Eotyrannus is a basal tyrannosaurid) sooner or later there will be a more basal tyranbnosaurid making the name a slight misnomer. It just drives me nuts. It weas Ok when we had a few hundred to deal with, but now poor idnetifications and half-arsed cladistic analyses lead to endless badly-named or mis-named taxa.

    C’mon taxonomists and systematicists, get those Greek and latin dictionaries out. There are far more words (or at least synonyms) out there for ‘hunter’ besides ‘venator’ or ‘raptor’!

  11. #11 Dave Godfrey
    May 25, 2007

    Eventually you’ll have to have Eoproprotoeotyrannus.

    Why are the tetrapod people repeatedly being outdone by the invertebrate guys? I want to see dinosaurs with names as descriptive and euphonious as Osedax mucofloris.

  12. #12 Dr Vector
    May 26, 2007

    I get very annoyed with Pro-taxon and Eo-taxon that a few years down the line somewhat inevitably turn out to be completely unrelated to the taxon they were named for (Procompsognathus, Protoaves etc.).

    Ha! You’ll be happy to hear, then, that one of the names we considered and abandoned for Sauroposeidon was Proteleosaurus. We ditched it because we didn’t want anyone to think our giant sauropod was a primitive marine crocodile. But we liked proteles enough to save it for the specific epithet.

    I filled a couple of notebook pages with possibilities before hitting on Sauroposeidon. I ought to dig those out and blog about them one of these days. I really liked some of them.

    The published record usually only gives you one version of the story. I am always interested in the other versions–the observations, intepretations, figures, and names that didn’t quite make it (or got axed during peer review!).

    That brings up a question. Have you ever cut an especially good chunk of text from one manuscript because of a pissy review, only to transfer it intact into another, later manuscript? And if you’ve done that more than once, does that mean that your papers are all too alike? Yikes! I rambled until I scared myself, so I’ll shut up now.

The site is currently under maintenance and will be back shortly. New comments have been disabled during this time, please check back soon.