BOSTON -- In a venture once thought to lie outside the reach of science, researchers from Harvard Medical School and Beth Israel Deaconess Medical Center have captured and sequenced tiny pieces of collagen protein from a 68 million-year-old Tyrannosaurus rex. The protein fragmentsseven in allappear to most closely match amino acid sequences found in collagen of present day chickens, lending support to a recent and still controversial proposal that birds and dinosaurs are evolutionarily related. The HMS and BIDMC researchers, working with scientists at North Carolina State University, report their findings in the April 13 Science.
"Most people believe that birds evolved from dinosaurs, but thats all based on the architecture of the bones," said John Asara, director of the mass spectrometry core facility at Beth Israel Deaconess Medical School and HMS instructor in pathology, who sequenced the protein fragments over the course of a year and a half using highly sensitive mass spectrometry methods. "This allows you to get the chance to say, Wait, they really are related because their sequences are related. We didnt get enough sequences to definitively say that, but what sequences we got support that idea."
In another study appearing in the same issue of Science, Mary Schweitzer, of North Carolina State University, and colleagues found that extracts of T. rex bone reacted with antibodies to chicken collagen, further suggesting the presence of birdlike protein in the dinosaur bones.
The mere existence of such exceedingly ancient protein defies a longstanding assumption. When an animal dies, protein immediately begins to degrade and, in the case of fossils, is slowly replaced by mineral. This substitution process was thought to be complete by one million years.
"For centuries it was believed that the process of fossilization destroyed any original material, consequently no one looked carefully at really old bones," said Schweitzer
Contact: John Lacey
Harvard Medical School