Tyrannosaurus rex just got a firm grip on the animal kingdom’s family tree, right next to chickens and ostriches. New analyses of soft tissue from a T.rex leg bone re-confirm that birds are dinosaurs’ closest living relatives.
“We determined that T. rex, in fact, grouped with birds – ostrich and chicken – better than any other organism that we studied,” said researcher John Asara of Beth Israel Deaconess Medical Center and Harvard Medical School. “We also show that it groups better with birds than [with] modern reptiles, such as alligators and green anole lizards.”
Scientists long suspected non-avian dinosaurs were most closely related to modern-day birds. This idea initially rested largely on similarities between the outward appearances of bird and dinosaur skeletons. Later, further evidence on the close evolutionary relationships among birds and non-avian dinosaurs accumulated.
A leg bone full of key gunk
The latest evidence comes from an ancient femur bone unearthed in 2003 by Jack Horner of the Museum of the Rockies in the Hell Creek Formation, a fossil-packed area that spans Montana, Wyoming and North and South Dakota.
It seems some 68 million years ago, a teenage T. rex died and left behind a drumstick-shaped femur bone that today still contains intact soft tissue and the oldest preserved proteins discovered to date.
Though no genetic material was preserved, researchers were able to extract the proteins from the collagen tissues.