Academic journal article Science Scope

A Breath Away from Extinction

Academic journal article Science Scope

A Breath Away from Extinction

Article excerpt

University of Utah scientists discovered that air flows in one direction as it loops through the lungs of alligators, just as it does in birds. The study suggests this breathing method may have helped the dinosaurs' ancestors dominate Earth after the planet's worst mass extinction 251 million years ago.

Before and until about 20 million years after the great extinction, mammal-like reptiles known as synapsids were the largest land animals on Earth. The extinction killed 70 percent of land life and 96 percent of sea life. As the planet recovered during the next 20 million years, archosaurs (Greek for "ruling lizards") became Earth's dominant land animals. They evolved into two major branches on the tree of life: crocodilians, or ancestors of crocodiles and alligators, and a branch that produced flying pterosaurs, dinosaurs, and eventually birds, which technically are archosaurs.

By demonstrating one-way or "unidirectional" airflow within the lungs of alligators, the new study suggests that such a breathing pattern likely evolved before 246 million years ago, when crocodilians split from the branch of the archosaur family tree that led to pterosaurs, dinosaurs, and birds. …

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