The skulls of three hadrosaur dinosaurs, Lambeosaurus lambei (top left), Gryposaurus notabilis (top right), and Parasaurolophus walkeri (lower).
Albert Prieto-Márquez.
The duck-billed hadrosaurs walked the Earth over 90-million years ago and were one of the most successful groups of dinosaurs. But why were these 2-3 tonne giants so successful? A new study, published in Paleobiology, shows that their special adaptations in teeth and jaws and in their head crests were crucial, and provides new insights into how these innovations evolved. Called the 'sheep of the Mesozoic' as they filled the landscape in the Late Cretaceous period, hadrosaurs walked on their hind legs and were known for their powerful jaws with multiple rows of extremely effective teeth. They also had hugely varied head display crests that signalled which species each belonged to and were used to attract mates. Some even trumpeted and tooted their special call, using nasal passages through the head crests. Researchers from the Universities of Bristol and the Catalan Institute of Paleontology in Barcelona used a large database describing morphological variety in hadrosaur fossils and computational methods that quantify morphological variety and the pace of evolution. Dr Tom Stubbs , lead author of the study and a researcher from Bristol's School of Earth Sciences, said: "Our study shows that the unique hadrosaur feeding apparatus evolved fast in a single burst, and once established, showed very little change.
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