Every breath you take traces back to a deep evolutionary past. The steady rise of your chest, the muscles between your ribs expanding outward, and the flow of air into your lungs feel routine. Yet this familiar process has ancient origins. A small, mummified reptile that died in an Oklahoma cave around 289 million years ago has revealed the earliest known example of this breathing system in amniotes – a group that includes reptiles, birds, mammals, and their shared ancestors, some of the first animals to fully adapt to life on land.

Ancient Fossil Reveals Early Breathing System
In a study published in Nature, researchers describe the remarkable preservation of Captorhinus aguti, a small reptile from the early Permian period. Though only a few inches long, this fossil contains far more than bones. It preserves three-dimensional skin, calcified cartilage, and even traces of proteins. These protein remnants are nearly 100 million years older than any previously identified in fossils.

“Captorhinus is an interesting lizard-looking critter that is critical to understanding early amniote evolution,” said Ethan Mooney, who co-led the study while a student at the University of Toronto in co-author Professor Robert R. Reisz’s lab and is now a PhD candidate in the Department of Organismic and Evolutionary Biology at Harvard University where he works with paleontologist Professor Stephanie Pierce. These early reptiles ranged in size from just a few centimeters to several feet and were among the first to explore life on land. They were widespread and successful during their time.