Discovery: giant flying squirrels once lived in North America 🐿️

About 5 million years ago, a giant flying squirrel, the size of a cat, glided over the forests of what is now Tennessee, alongside rhinos and mastodons. This unexpected discovery sheds light on the mysteries of prehistoric biodiversity in North America.


The Gray fossil site in northeastern Tennessee continues to reveal paleontological treasures. Among them, the remains of a giant flying squirrel, Miopetaurista webbi, have recently been identified. This specimen, weighing approximately 3 lbs (1.4 kg), is three times heavier than modern gray squirrels.

A surprising migration from Eurasia

The genus Miopetaurista was previously known mainly in Eurasia, where its fossils have been widely documented. Its presence in North America, confirmed by the fossil discovered at the Gray site, suggests a migration via the Bering Land Bridge about 5 million years ago. The subsequent period, warmer than today, allowed these animals to adapt to the humid forests of Tennessee, where they coexisted with a diverse fauna.

Researchers were particularly surprised by this discovery, as previous evidence of flying squirrels in North America was rare and uncertain. Before this find, only a few vague mentions in Florida hinted at their existence. The Gray fossil, however, provides solid confirmation, showing that these animals did indeed live on the continent.

This migration is part of a broader movement of fauna between Asia and North America during the Pliocene. Favorable climatic conditions allowed many species, including Miopetaurista, to cross the Bering Land Bridge. This discovery highlights the importance of biological exchanges between continents in the evolution of prehistoric ecosystems.

A master of gliding flight

These giant squirrels were perfectly adapted to arboreal life, thanks to their large flight membranes, called patagia. These structures, stretched between their limbs, allowed them to glide over long distances. This ability was essential for escaping predators and moving efficiently through the dense forests of the time.

Their agility in the trees made them privileged inhabitants of the humid Pliocene forests. Their diet, likely composed of fruits, nuts, and leaves, was well-suited to this vegetation-rich environment. Their relative lightness, despite their imposing size, allowed them to move effortlessly through the canopy.

However, climate changes eventually overcame their adaptations. The glaciations of the Pleistocene gradually isolated these animals in warmer refuges, such as Florida, before leading to their extinction. This disappearance illustrates the impact of climatic variations on the survival of species, even those best adapted to their environment.