Researchers at the Gray Fossil Site and Museum in northeastern Tennessee, have recently uncovered the remains of a 4.9-million-year-old giant flying squirrel (Miopetaurista webbi).

The site, which has already yielded an impressive range of prehistoric creatures, including red pandas, rhinoceroses, and even the world’s largest known collection of tapir fossils, continues to surprise scientists with its potential for revealing new insights into ancient life.

A Prehistoric Squirrel From Eurasia

While the genus has a longstanding presence in Eurasia, researchers were taken aback by the discovery of this specimen in North America. Prior to this find, there had only been some uncertain reports of flying squirrels in Florida, but they lacked the concrete evidence needed to confirm the species’ presence.

This fossil, however, provides definitive proof that these giant flying squirrels, which weighed about 1.4 kg—three times heavier than today’s typical gray squirrels—once roamed North America.

This discovery is particularly significant because it suggests that these creatures crossed the Bering Land Bridge, which once connected Asia and North America, around 5 million years ago.

Dr. Isaac Casanovas-Vilar, from the Institut Català de Paleontologia in Spain, noted that ” 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 Giant Flying Squirrel: A Master Of The Treetops

These ancient gliders, though seemingly similar to the smaller squirrels we see today, were uniquely adapted to life in the treetops. The giant flying squirrels had large, expansive gliding membranes that allowed them to travel great distances through the air, a feature that helped them escape predators and navigate the dense, humid forests of their time.

The Miopetaurista webbi was well-suited to the warm climate that prevailed in the region during the Pliocene epoch. This period was significantly warmer than today, creating the ideal environment for the ancestors of these giant squirrels to spread into North America.

The Ice Age’s Impact On Extinction

However, as the climate gradually cooled during the Ice Ages, the world underwent significant environmental changes, which affected species distribution.

According to Montserrat Grau-Camats, also from the Institut Català de Paleontologia,“ 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,”.

The last Miopetaurista species in North America lived long after the genus disappeared from Eurasia, effectively becoming “living fossils.” This observation highlights the impact of climate change on the survival of species, and how rapidly shifting conditions can lead to the disappearance of even the most well-adapted creatures.

The Ongoing Significance of the Gray Fossil Site

The Gray Fossil Site, managed by East Tennessee State University’s Don Sundquist Center of Excellence in Paleontology, continues to be a vital resource for understanding the prehistoric past of Appalachia.

In addition to the giant flying squirrel, many other significant fossils have been found here, including the remains of a bone-crushing dog, ancient plants, and other animal species.

Dr. Joshua Samuels, a researcher from East Tennessee State University, expressed his excitement about the discovery. “It is amazing to imagine these giant flying squirrels gliding over rhinos and mastodons living in the forests of Tennessee 5 million years ago,” he explained.