Wednesday, 20 January 2016

A new Welsh dinosaur - a basal most neotheropod

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0145713

Whilst exchanging emails with my PhD supervisor Dave Martill regarding the final submission of my Aerodactylus paper with PLoS one I received an email that was a bit of an unexpected segue. It read to the effect of "well done" for submitting the paper and "do you have a dinosaur data matrix in your computer? Particularly, one of the several theropod matrices that are kicking around". "Intriguing" I thought.

So it was April 2014 and I found myself being suitably distracted from my primary work on pterosaur cladistics by some photographs taken in a living room of grey blocks of rock containing what look like dinosaur bones. The kind of awful scraps of bone scattered across blocks that I've come to expect from British palaeontology. As we flicked through more and more photos though, it became a little less typical as it became clear that there was a lot of this animal. Even better, there was still preparatory work to be carried out to reveal more of the bones. This was quite a complete little dinosaur.

When we started to get to know the collectors, Rob and Nick Hanigan, that were responsible for its collection and documentation it became clear that this dinosaur was even more important than we had previously thought. The dinosaur was from Lavernock Point near Cardiff. A place not often associated with fossils, let alone dinosaurs. However, what Lavernock is known for is its exposure of the Rhaetian Bone Bed and the Psiloceras beds that mark the beginning of the Jurassic. This dinosaur was found in an almost unbroken sequence of rocks between the last definitive occurrence of the Triassic and the first definitive marker of the Jurassic.

Ordinarily, straddling a geological age or epoch even isn't going to be a big deal, but this is the end Triassic. Which means the end Triassic extinction. This is the dinosaur that came out the other side of a mass extinction and lived to tell the tale.
Pencil sketch by Bob Nicholls
 The dinosaur was very young and as a result many of its bones, especially in the skull, hadn't fused up. The animal sat on the sea floor after being washed out and sinking, where many animals including echinoderms (sea urchins) picked over the bones, scattering them. Despite this scattering of disarticulated bones there is still ~40% of the animal preserved. Thanks to symmetry and comparative anatomy this means we know around 80% of the animals anatomy.

Reconstruction / Jurassic World parody by Steven Vidovic

The dinosaur is a theropod, which is the fast, agile, fearsome type of dinosaur we know from books, TV and film. This is obvious to most seasoned palaeontologists, given that it has a specialized ankle for being a biped and dagger-like teeth with serrations. More specifically it is a neotheropod and most basal (primitive - if that was an acceptable word) coelophysoid.
Water colour of Dracoraptor by Steven Vidovic


So thanks to this discovery in Wales we know that small 2-3 meter dinosaurs like Coelophysis were surviving the extinction event, and it was their common ancestor with dinosaurs like Dilophosaurus gave rise to T. rex, Velociraptor and modern birds among others.

We let the original discoverers name the dinosaur as a nice gesture. They named it Dracoraptor hanigani.



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