By William Mullen | Chicago Tribune reporter
September 30, 2008
Fossils of a 33-foot-long, previously unknown meat-eating dinosaur discovered in South America are delivering insights to scientists on the long-suspected evolutionary relationship between dinosaurs and modern birds.
The team that found the fossils, a joint American-Argentinian expedition led by University of Chicago paleontologist Paul Sereno, says the dinosaur breathed 85 million years ago the same way as birds do today: with a unique, bellows-like system.
The find suggests many dinosaur species likely were breathing in this manner even before this dinosaur came along and bolsters decades of paleontological research indicating birds originally evolved from dinosaurs.
Found in the Patagonian badlands of Argentina in 1996 and studied in the dozen years since, the dinosaur was introduced to the scientific literature Monday in the online journal Public Library of Science ONE.
Its name tells much of the story; the dinosaur was dubbed Aerosteon riocoloradensis, or "air bones" from the Rio Colorado. Though the size of an elephant, Aerosteon (air-AHHS-tee-on) had many lightweight, hollow, birdlike bones—and that birdlike system of breathing.
"In breathing, bird lungs don't expand and contract," Sereno said by telephone from Mendoza, Argentina, where he is attending an international paleontological meeting. "Instead birds have a system of bellows–air sacs–that shunt air through the bird's 'rigid' lungs."
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