(Above) Teeth from the lower jaw of a hadrosaur, Edmontosaurus, showing its multiple rows of leaf-shaped teeth. The worn, chewing surface of the teeth is towards the top. Photo Vince Williams, University of Leicester.
In a discovery that could help unlock the eco systems of the dinosaurs, scientists say they have revealed how – and what – duck billed dinosaurs of the Cretaceous period ate.
65-68 million years ago, until their extinction, duck-billed dinosaurs – or hadrosaurs - were the World’s dominant herbivores. Now research, undertaken by the University of Leicester and the Natural History Museum, has found evidence that the giant 13 metre-high, three-tonne plant eaters had a unique way of eating, unlike any living creature today.
By studying the microscopic scratches preserved on a fossilised hadrosaur’s teeth, the team has found that the movements of its jaw were complex and involved up and down, sideways and front to back motion.
(Above) Teeth from the upper jaw of a hadrosaur, Edmontosaurus. The specimen was moulded and coated with gold for examination using a Scanning Electron Microscope to give high power magnification of the microscopic scratches. Photo: Vince Williams, University of Leicester.
According to Paul Barrett, palaeontologist at the Natural History Museum, the discovery, “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,” he said. “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 each other, grinding and shredding food in the process.”
The resulting microscopic scratches from this unusual action cover an area only as wide as two human hairs but have offered vital clues as to the type of food the big hadrosaurs ate.
Electron Microscope view of the surface of one of the hadrosaur teeth, showing the scratches created about 67 million years ago by tooth movements and feeding. The small black boxes show the areas, each less than half a millimetre wide, in which scratches were analysed. Photo: Vince Williams, University of Leicester.
“We can tell from the scratches that the hadrosaur’s food either contained small particles of grit, normal for vegetation cropped close to the ground, or, like grass, contained microscopic granules of silica,” added Vince Williams of the University of Leicester.
“We know that horsetails were a common plant at the time and have this characteristic; they may well have been an important food for hadrosaurs.”
Scientist now think the research could have the potential to tell us a lot more about dinosaur feeding and the ecosystems in which they lived.
