The Tyrannosaurus rex terrorised the ancient world for 85 million years but its closest living relative turns out to be the chicken, research suggests.

The dinosaur may have been armed with 60 dagger-like teeth and boasted the biggest bite of any land animal but analysis of a fossilised bone shows close similarities with modern-day chickens.

Researchers established the link after discovering that a small quantity of soft tissue had been preserved in a 68-million-year-old bone.

Chemical analysis of protein extracted from the fossil showed it to be collagen, the material that gives bone its structure and flexibility.

Further tests using mass spectrometry identified amino acids, which, when compared with those in modern animals, found them to be most closely related to those in chicken bones.

It is the first time that protein has been extracted from fossilised dinosaur remains.

Success in extracting and identifying dinosaur protein opens up the possibility that the evolution of ancient animals could be traced through chemical analysis.

The newly developed techniques involved in identifying the amino acids will have applications in medical research.

In one of two reports outlining the findings, published in the journal Science, the researchers said the same approach could be applied to identify protein sequences in living organisms and “to discover mutations in diseased tissues such as cancers”.

The soft tissue preserved in a T. rex leg bone found at the Hell Creek Formation in Montana was discovered by Mary Schweitzer of North Carolina State University. She was convinced that protein remained preserved in the fossil but was able to confirm it only after a series of experiments.

The link was not a surprise to researchers because birds are believed by palaeontologists to be descended from dinosaurs.

Dr Schweitzer said that the similarity with the chicken was what they expected.

She added: “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 medical implications for treating disease.”

Dr Schweitzer said that her team had searched for collagen because it was easy to identify and was unlikely to have been produced by microbes in the rock the bone was found in.

It had previously been deemed impossible for organic materials to survive for more than about a million years.

The amino acid sequencing technique was also applied to a fossilised mastodon, estimated to be about half a million years old. It was found to be more closely related to dogs, cattle, humans and elephants than any nonmammalian species.

John Asara, of the Beth Israel Deaconess Medical School in Boston, who led the sequencing study, said that they did not have enough sequences to make a definitive link between the T. rex and the chicken, but the sequences that they did obtain supported the theory.

Meet the family

— Researchers discovered a small quantity of collagen protein in a fossilised Tyrannosaurus rex femur, above, 68 million years old

— Connective tissue from a mastodon between 160,000 and 600,000 years old has also been found

— Analysis of the protein sample shows that modern chickens are the nearest living ancestors to T. rex

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