New find: Tyrannosaurus rex relationship to birds

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New find: Tyrannosaurus rex relationship to birds

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Date: 6/2/05 at 7:50PM

Mood: Thinking Playing: I’m a little dinosaur, by Jonathan Richman

June 2, 2005 WASHINGTON – A Tyrannosaurus rex dinosaur that died 68 million years ago has provided some of the strongest evidence yet that birds are the closest-living relatives of dinosaurs, scientists said Thursday.

Soft tissue found in the animal’s thighbone strongly suggests it was a female, and just about to lay eggs, the researchers report in Friday’s issue of Science.

The bone tissue is strongly similar to that made inside the bones of female birds — and no other living type of animal — when they are producing the hard shells of eggs just before they lay them, said Mary Higby Schweitzer of North Carolina State University in Raleigh.

“In addition to demonstrating gender, it also links the reproductive physiology of dinosaurs to birds very closely.

It indicates that dinosaurs produced and shelled their eggs much more like modern birds than like modern crocodiles,” Schweitzer told reporters in a telephone briefing.

Female birds produce a layer of bone tissue called medullary bone when they are laying eggs.