Similarly, it was speculated that one-way airflow may have helped the ancestors of dinosaurs roam the Earth beginning roughly 251 million years ago, after the Permian-Triassic mass extinction that wiped out up to 70 percent of terrestrial vertebrate species. Following the devastating extinction event, which formed the boundary between the Permian and Triassic periods, the level of atmospheric oxygen was thought to be significantly lower than today's levels.
In 2010, Farmer published a study detailing similar unidirectional airflow in alligators, which suggests the breathing pattern likely evolved about 250 million years ago, when the ancestors of alligators and crocodiles split from the ancient archosaurs, the group that led to the evolution of dinosaurs, flying pterosaurs and eventually birds.
But now, the discovery of one-way airflow in monitor lizards indicates the breathing method may have evolved even earlier -- about 270 million years ago -- among cold-blooded diapsids, which were the common, cold-blooded ancestors of present-day lizards and snakes, Farmer said.
"We need to look at other animals in different ecological niches, but I would not be surprised to find that this is very common in other cold-blooded vertebrates," she said.
The detailed findings of the study were published online today (Dec. 11) in the journal Nature.
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