Protein retrieved from a 68-millon-year-old Tyrannosaurus rex bone closely resembles the main protein in chicken and ostrich bones and is only distantly related to lizards', strengthening the popular idea that birds, and not reptiles, are the closest living descendants of dinosaurs.
The new work builds on a 2007 analysis showing remarkably close similarities between T. rex collagen and collagen from modern-day chickens, but that work did not include comparisons to other living species. Collagen is the primary protein in bones.
"We had made a very loose connection at first," said John Asara of Harvard Medical School and Beth Israel Deaconess Medical Center, who led both studies. "Now we're able to make out robust evolutionary relationships and, with very high confidence, basically group the T. rex dinosaur with birds."
More is at stake than T. rex's prehistoric pedigree. Asara and his colleagues say their novel approach has the potential to redraw the evolutionary tree based on molecular data instead of the traditional comparisons of skeletal remains. Bones can be deceiving, because unrelated animals can have similar structures.
WASHINGTON POST
