Galve: giant mystery crocodyliforms and, yay, more istiodactylids

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).

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).

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.

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.