May 23, 2016

By Katie Pavid

CT scans of the Stegosaurus stenops specimen have helped researchers piece together the eating habits of different herbivores. The specimen - the most complete stegosaur in the world - was acquired by the Museum in 2014. New research, published in Scientific Reports, compares the dinosaur's skull to those of Plateosaurus and Erlikosaurus. The skulls of the three dinosaurs look remarkably similar, but scientists found that each one ate in a very different way. Professor Paul Barrett, a Museum palaeobiologist who leads the research team working on the Stegosaurus, says: 'Our key finding really surprised us. We expected that many of these dinosaur herbivores would have skulls that worked in broadly similar ways. 'Instead, we found that even though the skulls were fairly similar to each other in overall shape, the way they worked during biting was substantially different in each case. 'This information allows us to understand more about their different feeding specialisms.' Plant eaters Several groups of dinosaurs developed plant-based diets independently of each other, despite being unrelated and having very different body shapes. Some walked on all fours, others on their hind limbs only, and others developed long necks.

However, many of these herbivores had long, narrow skulls, scissor-like jaw actions and similar arrangements of teeth. The study investigated the skulls of specimens from three groups - sauropodomorphs, theropods, and ornithischians. The Museum's Stegosaurus stenops specimen represented the ornithischians. Barrett says, 'Although Stegosaurus has been known about for more than 130 years, not much is known about its biology. 'Because the Museum's skeleton is almost complete - and three-dimensional - we can do a lot of things that have not been possible until now. 'The bones in our specimen's skull are separated from each other, so we can see how the skull fits together in 3D. We can then use this information to see how the skull would work as a chewing machine.' A powerful bite Digital models were made of the skulls and lower jaws, using CT scans of the original specimens. The results show that, despite their similar skulls and teeth, the biomechanical behaviours of the dinosaurs are notably different.

Their biomechanics probably reflect dietary specialisations and differing feeding habits. In turn, these distinct feeding habits might reflect the vegetation available in their local environment. Researchers found that Stegosaurus had a particularly powerful bite for a herbivorous dinosaur. Barrett said, 'The high bite force of Stegosaurus was another surprise. It was much stronger than previously suspected. 'We found that far from being feeble, Stegosaurus actually had a bite force within the range of living herbivorous mammals, such as sheep and cows.' More on the menu The shape of the Stegosaurus skull allowed for more jaw muscle mass than the other herbivores. This meant a more efficient conversion of muscle strength into the force of the bite. The research shows that Stegosaurus would have been capable of foraging on a wide variety of plants, including ferns and cycads. It probably had access to a wider range of potential food sources than Plateosaurus, which would have relied on more tender vegetation. Erlikosaurus had a skull that was specialised to exploit its beak-like tip. Barrett said, 'It is very tempting to assume that because the skulls of these dinosaurs were very similar, their feeding habits were also the same. But our data indicate this was not the case. 'These computer-based methods give us detailed insights into dinosaur biology that were not previously possible, and this represents the first ever detailed study of feeding in Stegosaurus.'

http://www.nhm.ac.uk/our-science/science-news/2016/may/dinosaur-eating-habit-insights-stegosaurus-stenops.html