Protein scraps help fill in dino family tree

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - Scraps of protein from the bones of a 68 million-year-old dinosaur and a mastodon carcass confirm their places in the family tree of life on Earth, researchers reported on Thursday.

The same team that established Tyrannosaurus rex is a distant relative of chickens filled in more gaps, showing that the dinosaur was far more closely related to living birds than to alligators.

And a 500,000-year-old mastodon is clearly a close relative of elephants, John Asara and colleagues at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston reported.

They said their analysis of the ancient preserved proteins can be used to fill in all sorts of gaps in the tree of evolution. But it also shows that classical methods, based on studying an animal's bones and other physical structures, are accurate.

"If you ... just use molecular data, you can come to the same conclusion," Asara said in a telephone interview.

Asara's team used collagen taken from a remarkable find -- the leg bone of a T. rex sealed in stone and broken when researchers had no other way of removing it.

Mary Schweitzer of North Carolina State University was able to get soft tissue and then protein out of the bone in 2005 -- something previously considered impossible. She also got protein out of the much younger mastodon bone.

Asara's team looked at the protein on a molecular level and designed a computer program to analyze it. A year ago, they established that the Tyrannosaurus was related to modern chickens and ostriches and that the mastodon was related to living mammals.