Fossil shows that chickens are descended from T Rex

Protein resembling that found in chicken has been extracted from a 68-million-year-old Tyrannosaurus rex bone, providing further evidence of the evolutionary link between dinosaurs and birds.

The collagen tissue was removed from a fossilised thigh bone belonging to one of the giant predator dinosaurs. Analysis showed it was structurally similar to chicken protein.

The bone was unearthed in 2003 in the American state of Montana. Two years later, the find hit the headlines with the discovery that it seemed to contain soft tissues, including blood vessels.

Writing yesterday in the journal Science, researchers at North Carolina State University confirmed they had found fragments of the protein collagen preserved in the fossil. Mary Schweitzer, who led the US team, said: "For centuries it was believed that the process of fossilisation destroyed any original material, consequently no one looked carefully at really old bones."

The researchers used mass spectrometry to show the Tyrannosaurus fossil contained sequences of amino acids - protein building blocks - typical of collagen. The pattern looked like that of chicken collagen, and there were also similarities with frog and newt protein. "The similarity to chicken is definitely what we would expect given the relationship between modern birds and dinosaurs," said Dr Schweitzer.

"This data will help us learn more about dinosaurs' evolutionary relationships, about how preservation happens, and about how molecules degrade over time, which could also have some important medical implications for treating disease."