Fingernails, Bird Beaks and Dinosaurs Have Keratin Connection

Keratin, the substance our fingernails and rhinoceroses' horns are made of, has been a feature on the appendages of animals dating at least as far back as the Cretaceous Period some 90 million years ago, according to a research team that has found evidence of keratin-covered dinosaur beaks in fossils unearthed in Mongolia.

Writing in the Proceedings of the National Academy of Sciences, researchers detail their analysis of the skull of a large herbivorous dinosaur called a therizinosaur (Erlikosaurus andrewsi), showing that part of its snout was covered in keratin. What's more, the researchers concluded that the keratin played an important role in stabilizing the dinosaur's skeletal structure during feeding, which they contend made the skull less susceptible to bending and deformation.

It might not be readily apparent, but modern bird's beaks are an evolutionary carryover from dinosaurs.

"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," said Stephan Lautenschlager of the University of Bristol's School of Earth Sciences.

Lautenschlager and his research colleagues, including Bristol's Emily Rayfield, Perle Altangerel of the National University of Ulaanbaatar in Mongolia and Lawrence Witmer of Ohio University, used high-resolution X-ray CT scans and computer simulations to carry out their research.

"Using Finite Element Analysis, a computer modeling 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," the paleobiologist Rayfield 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."

Witmer, who is a professor of paleontology at Ohio University, noted the evolutionary significance of his team's find.

"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," he said.