T. rex: a new link to birds

Analysis of proteins in the soft tissues of an amazingly well preserved specimen of Tyrannosaurus rex indicates the animal's closest living relatives are not reptiles, but birds. The evidence comes from a femur discovered in 2003 in the famous Hell Creek Formation in the north-central United States. The analysis was led by John Asara of Beth Israel Deaconess Medical Center and Harvard Medical School, who reports, "We determined that T. rex, in fact, grouped with birds – ostrich and chicken – better than any other organism that we studied. We also show that it groups better with birds than modern reptiles, such as alligators and green anole lizards."