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.

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.

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