Researchers have found the 4.9-million-year-old remains of a giant flying squirrel (Miopetaurista webbi) at the Gray Fossil Site and Museum in north-east Tennessee, US.
Gray Fossil Site – an ancient pond that formed within a sinkhole – has yielded many discoveries since it was unearthed in 2000 during the construction on Tennessee State Route 75, including new species of red panda, rhinoceros, pond turtle and hickory tree, as well as the world's largest known collection of tapir fossils – and now a giant flying squirrel.
The researchers, who published the latest discovery in the Journal of Mammalian Evolution, say that “finding Miopetaurista in North America was quite unexpected as this genus is only known from Eurasia."
“There had been some uncertain reports from Florida," says Dr Isaac Casanovas-Vilar from the Institut Català de Paleontologia in Spain, "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.”
According to the study, "the new specimen may represent the oldest record of the Miopetaurista genus in North America."
Prehistoric gliders
Although these ancient gliders may seem similar to the squirrels seen in the Appalachian woodlands today, their closest relatives are actually the giant flying squirrels of Japan, China and Indonesia.
Weighing around 1.4kg (3lb) – that's roughly three times as heavy as a grey squirrel (Sciurus carolinensis) – they were lightweight for their size, yet agile, perfectly adapted to life in the treetops.
When they first arrived in what is now Tennessee, the climate was much warmer than today, creating ideal conditions for their ancestors to spread into North America. They likely thrived in the dense, humid forests that once covered the region, much like the ancient woodland preserved at the Gray Fossil Site.
But as the Ice Ages took hold, dramatic environmental changes reshaped the landscape, explains Montserrat Grau-Camats (from the Institut Català de Paleontologia in Spain).
“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," says Grau-Camats.
"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'.”
Gray Fossil Site - an ancient treasure trove
Managed by the Don Sundquist Center of Excellence in Paleontology at East Tennessee State University, the Gray Fossil Site continues to transform our understanding of Appalachia’s prehistoric past, say the researchers.
The fossils found here, including that of the giant flying squirrel, are those of the ancient plants and animals that lived and died in and around the sinkhole.
The discovery of this giant flying squirrel adds to an impressive list of finds, including the formidable bone-crushing dog.
“It is amazing to imagine these giant flying squirrels gliding over rhinos and mastodons living in the forests of Tennessee 5 million years ago," says Dr Joshua Samuels from East Tennessee State University.
“This really points to the potential of the Gray Fossil Site to keep surprising us after 25 years.”
Main image: the giant flying squirrel once soared through the ancient forests of what is now the southern Appalachian Mountains/Getty
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