The Gray Fossil Site was once an ancient sinkhole lake surrounded by a dense forest of hickory, oak and pine trees, scientists say. The giant flying squirrels may have migrated east on the land bridge that connected Eurasia to North America, alongside saber-toothed cats, deer, shrews and a host of other animals, according to the study.

A giant flying squirrel, roughly the size of a house cat, once soared through the forests of what is now Southern Appalachia. Gliding above mastodons, rhinos, and red pandas, these agile creatures thrived millions of years ago before vanishing during the Ice Ages.

A giant flying squirrel—about the size of today's house cats—once soared through the skies over what is now Southern Appalachia, gliding above rhinos, mastodons and red pandas.

These giant flying squirrels had a lightweight build, weighing around three pounds – and were quite agile in the treetops.”

Researchers at East Tennessee State University found fossilized remains of a giant flying squirrel at the Gray Fossil Site, an unexpected discovery linking prehistoric ecosystems in North America and Eurasia.