Monday, January 14, 2008

Baryonyx (with a fish)

From the press release:

The unusual skull of Baryonyx is very elongate, with a curved or sinuous jaw margin as seen in large crocodiles and alligators. It also had stout conical teeth, rather than the blade-like serrated ones in meat-eating dinosaurs, and a striking bulbous jaw tip (or ‘nose’) that bore a rosette of teeth, more commonly seen today in slender-jawed fish eating crocodilians such as the Indian fish-eating gharial. Baryonyx walkeri is an early Cretaceous dinosaur, around 125 million years old, and belongs to a family called spinosaurs.

Baryonyx snout bone is transparent brown; the teeth (yellow) had extremely deep roots; Baryonyx independently evolved a bony palate (the pink structure), also seen in crocodilians. Credit: Emily Rayfield

Rayfield used computer modelling techniques to show that while Baryonyx was eating, its skull bent and stretched in the same way as the skull of the Indian fish-eating gharial
– a crocodile with long, narrow jaws. The results wer published in the latest JVP.

Dr Rayfield said: “On excavation, partially digested fish scales and teeth, and a dinosaur bone were found in the stomach region of the animal, demonstrating that at least some of the time this dinosaur ate fish. Moreover, it had a very unusual skull that looked part-dinosaur and part-crocodile, so we wanted to establish which it was more similar to, structurally and functionally – a dinosaur or a crocodile.

The results showed that the eating behaviour of Baryonyx was markedly different from that of a typical meat-eating theropod dinosaur or an alligator, and most similar to the fish-eating gharial. Since the bulk of the gharial diet consists of fish, Rayfield’s study suggests that this was also the case for Baryonyx back in the Cretaceous.