‘Incredibly rare’ giant flying squirrel fossil found in Tennessee — with ‘puzzling’ past

Scientists had an idea of what prehistoric Appalachia looked like: alligators coexisting with tapirs, turtles and carnivores that resemble modern-day red pandas.

Now, they are adding giant flying squirrels to the picture.

Researchers discovered a partial fossil of a giant flying squirrel estimated to be about 5 million years old at the Gray Fossil Site at East Tennessee State University, giving scientists more clues about how the creatures made their way to North America.

The finding of the species, part of the extinct Miopetaurista genus of flying squirrel, was “puzzling” to scientists, who published their research on the fossil discovery in the Journal of Mammalian Evolution on Feb. 21.

“Finding Miopetaurista in North America was quite unexpected as this genus is only known from Eurasia,” study author Isaac Casanovas-Vilar told ETSU. “There had been some uncertain reports from Florida, but the specimen of the Gray Fossil Site provided new information and helped to confirm that somehow these giant flying squirrels crossed the Bering Land Bridge alongside other mammals about 5 million years ago.”

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.

The squirrels settled in the wet and temperate forests of Appalachia about 4.5 million to 5 million years ago, researchers say. They are believed to be the youngest — and final — members of the Miopetaurista flying squirrel family.

“As the climate cooled over time, the Pleistocene Ice Ages led to the isolation of these giant flying squirrels in warmer refuges like Florida, and ultimately contributed to their extinction,” author Montserrat Grau-Camats told ETSU. “The last American Miopetaurista lived millions of years after all Eurasian species of this genus had disappeared, meaning at the time they were ‘living fossils.’”

Only one species from the Miopetaurista genus has ever been found in North America, the “incredibly rare” Miopetaurista webbi that’s been documented just twice, both times in very small fragments from Florida, the researchers said. According to ETSU, the prehistoric squirrels weighed about 3 pounds.

The creatures are believed to be related to the Petaurista family, which includes a living group of large flying squirrels in Asia.

In 25 years, nearly 200 species of plants and animals have been discovered in the sinkhole lake ecosystem at the Gray Fossil Site. The site was discovered by accident by a road construction crew in 2000.

This story was originally published February 25, 2025 at 1:41 PM with the headline "‘Incredibly rare’ giant flying squirrel fossil found in Tennessee — with ‘puzzling’ past."