A team of paleontologists from East Tennessee State University (ETSU) and the Autonomous University of Barcelona found a fossil of a giant flying squirrel at the Gray Fossil Site in Tennessee, dating back approximately 4.7 million years, according to IFLScience.
The specimen, identified as Miopetaurista webbi, represents the latest find from the Gray Fossil Site, a rich paleontological site in Washington County, Tennessee, which formed a sinkhole that filled with water around 5 million years ago, creating a pond that preserved many ancient species. The site has yielded numerous discoveries, including a species of powerful, bone-crushing dog found in 2022.
"Miopetaurista webbi were cat-sized squirrels that easily moved through the treetops, just as their modern relatives do in Asia," said researchers. These giant flying squirrels once glided through the landscape of Southern Appalachia around 4.7 million years ago, coexisting with rhinos, mastodons, and red pandas.
"It is amazing to imagine these giant flying squirrels gliding over rhinos and mastodons living in the forests of Tennessee 5 million years ago," said Dr. Joshua Samuels, a researcher at ETSU, according to IFLScience.
Miopetaurista webbi are more closely related to giant squirrels found in Japan, China, and Indonesia than to any squirrels living in Appalachia today. Despite their larger size, they weighed only about 1.3 kilograms (3 pounds), making them agile and well-adapted for gliding through dense forests.
Researchers state that the discovery confirms these mammals migrated to North America approximately five million years ago, likely crossing the Bering Land Bridge. "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," said Dr. Isaac Casanovas-Vilar of the Autonomous University of Barcelona, according to Greekreporter.com.
According to IFLScience, during the period when Miopetaurista webbi crossed into North America, the climate was warmer than it is today, which facilitated their migration through dense, humid forests. Flying squirrels vanished from the North American fossil record during the Late Miocene, around 9 million years ago, but reappeared during the Pliocene and Pleistocene epochs, approximately 5.3 and 2.6 million years ago.
Over time, as the climate cooled during the Pleistocene Ice Ages, these squirrels were forced into smaller, warmer regions like Florida, contributing to their eventual extinction. "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," said Montserrat Grau-Camats, a researcher at the Catalan Institute of Paleontology in Spain and study co-author, according to Live Science.
"This really points to the potential of the Gray Fossil Site to keep surprising us after 25 years," said Dr. Samuels.
Other fossils from the Gray Fossil Site reveal that the region was teeming with unusual wildlife when Miopetaurista webbi was alive, including rhinos, mastodons, red pandas, and bone-crushing dogs.
The findings related to the giant flying squirrel were published in the Journal of Mammalian Evolution, contributing to an understanding of the evolutionary history of these mammals.
Researchers are still learning about the history of flying squirrels, which have a spotty fossil record. The research team included Montserrat Grau-Camats and Dr. Isaac Casanovas-Vilar from Spain, Dr. Joshua Samuels from ETSU, and Cheyenne Crowe, a former ETSU paleontology student, according to Greekreporter.com.
"Miopetaurista webbi is potentially the oldest fossil of this genus ever found in North America, making it a significant find," researchers noted.
The Gray Fossil Site, managed by the Don Sundquist Center of Excellence in Paleontology at ETSU, continues to reveal new insights into Appalachia's ancient past. The site is up to a million years older than the two fossils found in Florida, offering a window into the region's prehistoric ecosystems.
The article was written with the assistance of a news analysis system.