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New test bolsters theory dinosaurs spawned birds
Researchers find that T. rex leg proteins are extraordinarily similar to modern chickens'.
By ASSOCIATED PRESS
Published April 13, 2007
WASHINGTON - Researchers have decoded proteins from a 68-million-year-old Tyrannosaurus rex, the oldest such material ever found. The unprecedented step, once thought impossible, adds weight to the idea that today's birds are descendants of the mighty dinosaurs. Scientists used a new, highly sensitive medical analyzer on the fossilized bones to unlock the dinosaur protein's molecular code. The feat, long presumed impossible because so little protein is present in dinosaur remains, opens the door to a redrawing of the evolutionary tree - one based on molecular evidence instead of the crude comparisons of bone shapes and sizes that experts now rely on. The results, described in today's issue of Science, show that the collagen protein in T. rex bone is extraordinarily similar to that of the modern chicken, confirming current thinking that dinosaurs' nearest cousins are birds. The new approach promises to settle far more contentious debates about the relationships among various extinct and surviving species, scientists said. Those links until now have been impossible to verify because DNA is degraded beyond recognition in remains that are more than a few tens of thousands of years old. By contrast, the new work unexpectedly shows that protein - a passable substitute for DNA for determining evolutionary relatedness - can survive reasonably intact for tens of millions of years. "This interplay between the fossil record and the molecular record will be more and more useful for understanding the evolution of life on this planet," said Mary Schweitzer of North Carolina State University in Raleigh, who led the studies with John Asara of Harvard Medical School and Beth Israel Deaconess Medical Center. Information from the Associated Press and Washington Post was used in this report.
[Last modified April 13, 2007, 01:41:27]
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