More Evidence for Dinosaur / Bird Link (broadcast Friday, April 25th, 2008)

T rex femur bone. Image © Science

In recent years, the link between ancient dinosaurs and present-day birds has become fairly widely accepted among paleontologists. Now, analysis of proteins found in a scrap of collagen from a 68-million-year-old Tyrannosaurus rex leg bone provides strong evidence for the idea that dinosaurs are the ancestors of modern-day birds. Researchers compared collagen-protein sequences from 21 living organisms to proteins recovered from mastodon and T. rex fossils, and used the data to help draw a molecular family tree showing the relationships between dinosaurs and modern animals.

“We determined that T. rex, in fact, grouped with birds – ostrich and chicken – better than any other organism that we studied," said John Asara, one of the authors of a paper on the analysis published this week in the journal Science. "We also show that it groups better with birds than modern reptiles, such as alligators and green anole lizards.” In this segment, Ira talks with researchers on the project about the work and what it means for our understanding of evolution.