Eating with dinosaurs

A new study shows that microscopic analysis of scratches on teeth can shed light on the past and has, in fact, shown that a species of dinosaur from the Cretaceous period chewed in a unique way.

The study, led by the University of Leicester and working with researchers from the Natural History Museum, used a new approach to analyse the feeding mechanisms of dinosaurs and understand their place in the ecosystems of tens of millions of years ago.

Palaeontologist Mark Purnell of the University of Leicester Department of Geology, who led the research, said: ‘For millions of years, until their extinction at the end of the Cretaceous period, duck-billed dinosaurs – or hadrosaurs – were the world’s dominant herbivores. They must have been able to break down their food somehow, but without the complex jaw joint of mammals they would not have been able to chew in the same way, and it is difficult to work out how they ate.

‘Our study uses a new approach based on analysis of the microscopic scratches that formed on hadrosaur’s teeth as they fed, tens of millions of years ago. The scratches have been preserved intact since the animals died. They can tell us precisely how hadrosaur jaws moved, and the kind of food these huge herbivores ate, but nobody has tried to analyse them before.’

The researchers say that the scratches reveal that the movements of hadrosaur teeth were complex and involved up and down, sideways and front to back motion. According to Paul Barrett, a palaeontologist at the Natural History Museum: ‘This shows that hadrosaurs did chew, but in a completely different way to anything alive today. Rather than a flexible lower jaw joint, they had a hinge between the upper jaws and the rest of the skull. As they bit down on their food the upper jaws were forced outwards, flexing along this hinge so that the tooth surfaces slid sideways across. One of the big surprises of this study is that so much information about such large animals can be gleaned from such a tiny patch of tooth.

‘By looking at the pattern of scratches in an area that is only about as wide as a couple of human hairs we can work out how and what these huge herbivores were eating,’ notes Vince Williams of the University of Leicester. ‘And because we can analyse single teeth, rather than whole skeletons, the technique has the potential to tell us a lot more about dinosaur feeding and the ecosystems in which they lived.’

The results have been published in the Proceedings of the National Academy of Sciences.