Did T. rex roar — or cluck instead?

WASHINGTON — It looks like chickens deserve more respect.

Scientists are fleshing out the proof that today's broiler-fryer is descended from the mighty Tyrannosaurus rex.

And, not a surprise, they confirmed a close relationship between mastodons and elephants.

Fossil studies have long suggested modern birds were descended from T. rex, based in similarities in their skeletons. Now, bits of protein obtained from connective tissues in a T. rex fossil show a relationship to birds including chickens and ostriches, according to a report in today's edition of the journal Science.

"These results match predictions made from skeletal anatomy, providing the first molecular evidence for the evolutionary relationships of a nonavian dinosaur," Chris Organ, a postdoctoral researcher in biology at Harvard University, said in a statement.

Co-author John Asara of Harvard reported last year that his team had been able to extract collagen from a T. rex and that it most closely resembled the collagen of chickens.

They weren't able to recover dinosaur DNA, the genetic instructions for life, but DNA codes for the proteins they studied.

While the researchers were able to obtain just a few proteins from T. rex, they have now been able to show the relationships with birds. With more data, Organ said, they would probably be able to place T. rex on the evolutionary tree between alligators and chickens and ostriches.

"We also show that it groups better with birds than modern reptiles, such as alligators and green anole lizards," Asara added.

The dinosaur protein was obtained from a fossil found in 2003 by John Horner of the Museum of the Rockies in a barren, fossil-rich stretch of land that spans Wyoming and Montana.

Mary Schweitzer of North Carolina State University and the North Carolina Museum of Natural Sciences discovered soft-tissue preservation in the T. rex bone in 2005.

The research of Organ and Asara indicates that the protein from the fossilized tissue is authentic, rather than contamination from a living species.

The researchers also studied material recovered from a mastodon fossil and determined it was related to modern elephants.

Their research was funded by the National Institutes of Health, National Science Foundation, Paul F. Glenn Foundation and the David and Lucile Packard Foundation.