Evolution Diary

A 68-million-year-old collagen sample yields evidence that the reptiles’ descendants are feathered.

Foghorn Leghorn would be proud.

The cantankerous Loony Tunes rooster and his brethren appear to be the closest living descendants of the ferocious Tyrannosaurus rex that ruled the world of dinosaurs.

That’s the conclusion of a team of researchers who analyzed a remarkable 68-million-year-old sample of T. rex tissue.

It began two years ago when paleontologist Mary H. Schweitzer and colleagues at North Carolina State University announced they had found bits of soft tissue inside a fossilized T. rex bone excavated from the Hell Creek Formation of Montana.

Researchers wouldn’t have known about the tissue except that they had to break the massive bone to load it into a helicopter. Inside, they found brownish oblong cells and translucent vessels so elastic they could still be stretched like rubber bands.

At the time, no detailed tests had been conducted on the material.

The new findings, reported today by Schweitzer’s team in the journal Science, show that part of the tissue is collagen, the fibrous protein forming the scaffolding that supports the minerals in bone.

Spectroscopist John M. Asara of Beth Israel Deaconess Medical Center in Boston then used technology developed to identify minute traces of proteins in tumors. He broke the collagen down into seven short fragments and analyzed the sequence of the 15 to 20 amino acids in each fragment.

Comparing those seven sequences with established genomes of modern species, they found three that matched chickens, one that matched a frog and another that matched a newt. The protein reacted to antibodies against chicken collagen.

The finding supports the theory that birds evolved from dinosaurs — an idea that until now had been largely based on comparing bone structures.

“This allows you to get the chance to say, ‘Wait, they really are related because their sequences are related,’ ” Asara said. “We didn’t get enough sequences to definitively say that, but what sequences we got support that idea.”

Reposted from LA Times