The T-Rex protein was taken from a thigh bone discovered in the US in 2003 and the study adds further weight to the argument that some dinosaurs evolved into birds.

Dr Chris Organ, the lead researcher in the project, said: "Even though we only had six peptides – 89 amino acids – from T-Rex, we were able to establish the relationship with a relatively high degree of support.

"With more data, we'd likely see the T-Rex branch on the tree between alligators, chickens and ostriches."

Science magazine said the fearsome dinosaur was closer to a chicken than a modern alligator in its molecular build-up.

Researchers used an analytical technique called mass spectroscopy to compare collagen from the T-Rex and a range of animal species, including birds and reptiles.

Dr John Asara, the project's director of spectroscopy, said: "We determined that T-Rex grouped with birds – ostrich and chicken – better than any other organism that we studied."