Thaindian News

Washington, Jan 15 (IANS) Birds’ breathing method may have helped their dinosaur forefathers dominate earth after its worst mass extinction 251 million years ago.
The extinction wiped out 70 percent of land life and 96 percent of marine life. As the planet recovered during the next 20 million years, archosaurs (Greek for “ruling lizards”) became Earth’s dominant land animals.

Before and until about 20 million years after the extinction - called “the Great Dying” or the Permian-Triassic extinction - mammal-like reptiles known as synapsids were the largest land animals on Earth, says a University of Utah (UU) release.

They evolved into two major branches on the tree of life: crocodilians, or ancestors of crocs and alligators, and a branch that produced flying pterosaurs, dinosaurs and eventually birds, which technically are archosaurs.

University of Utah (UU) scientists discovered that air flows in one direction as it loops through the lungs of alligators, just as it does in birds. Their study shows how such a breathing pattern evolved more than 246 million years ago.

“The real importance of this air-flow discovery in gators is it may explain the turnover in fauna between the Permian and the Triassic, with the synapsids losing their dominance and being supplanted by these archosaurs,” says C.G. Farmer, the principal study author.

Even with much less oxygen in the atmosphere, “many archosaurs, such as pterosaurs, apparently were capable of sustaining vigorous exercise,” adds Farmer, UU assistant professor of biology.

The findings were published in the Friday issue of Science.