People, ideas, and discoveries that impact North Carolina and the world

May 2008

Tyrannosaurus is Cousin to Modern-Day Chickens

T. Rex
The king of dinosaurs isn't so scary when you find out he's related to the chicken family.

By Tracey Peake 

Was the king of dinosaurs nothing more than a big chicken? You wouldn't say it to his face, but when it comes to the Tyrannosaurus rex family tree, it turns out that modern-day chickens can call the T. rex "cousin."

A group of researchers, including North Carolina State University paleontologist Dr. Mary Schweitzer, have used protein sequences from 68 million-year-old dinosaur collagen to determine the evolutionary relationships of T. rex. The results appear in the April 24 edition of Science.

Scientists Sequence Protein Found in Dino Bone 

Schweitzer, associate professor of paleontology at NC State with a joint appointment at the N.C. Museum of Natural Sciences, had previously discovered soft tissue in the leg bone of a T. rex recovered in 2003 from the Hell Creek formation in Montana.

She provided samples of collagen from the bone to her colleagues Dr. John Asara at Harvard Medical School and Beth Israel Deaconness Medical Center, and Dr. Chris Organ of the department of organismic and evolutionary biology at Harvard. Asara sequenced the protein, and found similarities between the peptides extracted from T. rex collagen protein fragments and those of modern-day chickens. However, these initial sequences were not analyzed phylogenetically, or in terms of where they might place T. rex within the evolutionary "family tree."

Family Tree Includes Gators and Chickens

The researchers then conducted multiple phylogenetic analyses by comparing the sequence data from T. rex and a mastodon fossil, to a database of sequence data from 19 animals, including living animals. The results place the non-avian T. rex within the class Archosauria between the ancestors of modern-day alligators and their avian relatives, the modern-day chicken. The mastodon, as expected, was found to be a relative of modern elephants, proving that the genetic material was authentic, and that trait evolution can be traced at the molecular level.

"The really interesting thing here is that we have hard evidence that it is possible to trace evolutionary traits of extinct animals through molecular analysis," Schweitzer says. "This will give us greater insight into the ways in which species evolve over time."