Beaks evolved in some dinosaurs in order to stabilise their skulls while gobbling down food, scientists say.
A new study has found that keratinous beaks played an important role in stabilising the skeletal structure during feeding, making the skull less susceptible to bending and deformation.
Beaks are a typical hallmark of modern birds and can be found in a huge variety of forms and shapes.
However, it is less well known that keratin-covered beaks had already evolved in different groups of dinosaurs during the Cretaceous Period.
Employing high-resolution X-ray computed tomography (CT scanning) and computer simulations, an international team of palaeontologists used digital models to take a closer look at these dinosaur beaks.
The focus of the study was the skull of Erlikosaurus andrewsi, a 3-4 metres large herbivorous dinosaur called a therizinosaur, which lived more than 90 million years ago during the Cretaceous Period in what is now Mongolia, and which shows evidence that part of its snout was covered by a keratinous beak.
"It has classically been assumed that beaks evolved to replace teeth and thus save weight, as a requirement for the evolution of flight.
"Our results, however, indicate that keratin beaks were in fact beneficial to enhance the stability of the skull during biting and feeding," Lead author Dr Stephan Lautenschlager of University of Bristol's School of Earth Sciences said.
"Using Finite Element Analysis, a computer modelling technique routinely used in engineering, we were able to deduce very accurately how bite and muscle forces affected the skull of Erlikosaurus during the feeding process," co-author Dr Emily Rayfield, Reader of Palaeobiology at Bristol said.
"This further allowed us to identify the importance of soft-tissue structures, such as the keratinous beak, which are normally not preserved in fossils," said Rayfield.
"Beaks evolved several times during the transitions from dinosaurs to modern birds, usually accompanied by the partial or complete loss of teeth and our study now shows that keratin-covered beaks represent a functional innovation during dinosaur evolution," co-author Lawrence Witmer from the Ohio University Heritage College of Osteopathic Medicine said.
The study was published in the journal Proceedings of the National Academy of Sciences (PNAS).
