Stegosaurus had bite like a sheep

By Matthew Stock

Dinosaur experts have conducted the first detailed study of the Stegosaurus skull and found that it had a more powerful bite than its tiny, peg-shaped, teeth suggested.

The scientists used digital models and computer simulations to compare the Natural History Museum’s Stegosaurus fossil with the Plateosaurus and Erlikosaurus; two other herbivorous dinosaurs with similar shaped skulls and a scissor-like jaw action.

Professor Paul Barrett, dinosaur researcher at London’s Natural History Museum, said advanced technology has given exciting new insights into dinosaur biology – something that would not have been possible several years ago.

“Stegosaurus was actually an animal that could get up to 9 metres in length and weigh several tonnes,” Barrett said while holding a Stegosaurus tooth. “This is the average size tooth for a Stegosaurus; pretty tiny with a business end, the crown, that’s really only a few millimetres across. So using these very tiny feeble teeth to fuel that big body has always been a bit of a mystery.”

The study was recently published in the journal Nature Scientific Reports.

Lead author Dr Stephan Lautenschlager, a post-doctoral researcher at the University of Bristol, used engineering software to give the digital skulls the material properties to match as closely as possible to the real thing. By attaching muscles to the 3D models, he was able to examine the forces that the jaws could produce and the subsequent stresses on the skulls.

Lautenschlager told Reuters that once the bones were placed in a CT scanner and accurate computer models made of each, they were ‘stitched’ together via computer software to make a model of the skull.

He added: “We then wanted to tell what the jaw muscles looked like, and we did that by comparing the jaws of living crocodiles and birds and lizards; and working out from those features what dinosaurs would have had. So working backward from what we know about living animals and applying them to the dead ones.”

Barrett worked with Lautenschlager in the research, along with other scientists from Manchester and Birmingham.

A key finding from the study showed that, despite having broadly similar shaped skulls, the way each dinosaur’s jaw worked while biting differed in each case. For Stegosaurus, the research found that it had a stronger bite than previously thought; suggesting its diet could have been quite different.

“Stegosaurus has always been thought to have a very weak bite and maybe just fed on soft pulpy vegetation. It turns out it actually has quite a strong bite very similar to that of a living cow or sheep; which doesn’t sound very much but actually if you’re a plant that’s a pretty bad thing to be bitten by. So they probably could have eaten plants that were much tougher and stronger than we used to think, and that has some big implications for how we imagine their ecology to be,” added Barrett.

Stegosaurus lived around 150 million years ago during the Jurassic period and needed to eat a lot of plants to sustain its large size. Modern grass didn’t exist then, so it would have fed on plants such as ferns and horsetails. But this new research suggests they may have had a wider diet of prehistoric flora; potentially playing a more important role in dispersal of plant seeds than previously believed.

“Instead of just feeding on mushy ferns or low-growing horsetails, it means they might have been much more important in munching tough plants like conifers or cycads, which suggests they may have been feeding on quite different things, maybe living in different environments from time to time, and even potentially acting as vectors for moving seeds and fruits around for those different types of plants,” said Barrett.