Hairy Museum of Natural History

Dilophosaur Edition

200,000,000 years ago, this snaggletoothed critter was at the top of the foodchain in the American Southwest. Dilophosaurus wetherelli (Wetherell’s Double-Crested Reptile) is known from fairly complete skeletal remains from the Early Jurassic of Arizona.

Dilophosaurus was one of the first large theropods (meat-eating dinosaurs), growing to a respectable length of 20 feet or so. It appears to be closely related to the smaller theropod Coelophysis, well-known from the Late Triassic of New Mexico. Features present in little Coelophysis are greatly exaggerated in its bigger cousin, like the unusual kink (or subnarial gap) that separates the tip of its snout from its upper jaw. Barely noticeable in the smaller version, it is a defining characteristic of Dilophosaurus.

Even its unusual crests have precedents in Coelophysis. One species that lived in Jurassic Arizona alongside of Dilophosaurus, called Coelophysis kayentakatae (formerly Syntarsus kayentakatae), bore two small, ridged crests above its snout. Dilophosaurus sported a much larger pair of these crests. They might have been used to impress other dilophosaurs, although it has been suggested that they were cooling devices to keep its brain from overheating.

The teeth of Dilophosaurus are much longer and more slender than in most other theropods, and are somewhat unusual in that they sat rather loosely in their sockets. This, combined with its unusually-shaped snout, has caused some speculation about its possible feeding habits. For the first large meat-eating dinosaur, it seems ill-equipped to bite into large prey. Its mouth does seem to be well-adapted to nip and grab, so it might have specialized in snagging small, fast animals. This corresponds nicely to what we know about the diet of its Coelophysis relatives.

Creationists often cite the mysterious teeth and fragile crests of Dilophosaurus as “proof” that meat-eating dinosaurs were so poorly designed for carnivory that they ate plants in Eden’s early paradise. I think, however, that an honest examination of the mouths of these animals would quickly dispel any notion that Dilophosaurus was sucking cycads alongside Adam and Eve.

More animal interactions available at this week’s Friday Ark.

—Matt Celeskey.

File under: Dinosaurs, Jurassic.