Flying squirrels the size of cats soared over prehistoric Appalachia

Recently analyzed fossils finally confirm a longtime paleontological theory: Flying squirrels the size of domesticated cats glided across the Bering Land Bridge roughly 5 million years ago. Although no longer native to North America, the ancestors to today’s aerodynamic rodents likely made the most of the Early Pliocene’s warmer climate.

The new findings come from an international research team collaborating between East Tennessee State University and Spain’s Institut Català de Paleontologia, and are described in a study published on February 21 in the Journal of Mammalian Evolution. The discovery of a Miopetaurista webbi specimen at the Gray Fossil Site in Washington County, Tennessee, surprised paleontologists given what they previously understood about the creature’s evolutionary journey.

“Finding Miopetaurista in North America was quite unexpected as this genus is only known from Eurasia,” Isaac Casanovas-Vilar, a study co-author and Institut Català de Paleontologia researcher, said in a statement. “There had been some uncertain reports from Florida, but the specimen of the Gray Fossil Site provided new information.”

Modern Southern Appalachia was much warmer during the Pliocene epoch, which lured  prehistoric mammal species east after crossing the Bering Land Bridge. Due to its Eurasian origins, the Miopetaurista that eventually soared through the trees of Tennessee all the way down to Florida were more closely related to today’s flying squirrels in China, Japan, and Indonesia than any North American squirrels.

While roughly the size of a cat, Miopetaurista webbi only weighed about 3 pounds.

Miopetaurista species are previously documented in areas of China, France, and Germany during both the Miocene (23-5.3 million years ago) and Pliocene (5.3–2.5 million years ago) epochs. But the discovery and dating of the Tennessee Miopetaurista webbi now means those flying squirrels were some of the last of their kind.

“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,” study co-author Montserrat Grau-Camats said. “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.'” This also meant the flying squirrels lived beside some unexpected neighbors.

“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 study co-author Joshua Samuels.

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