Gliding between continents: A review of the North American record of the giant flying squirrel Miopetaurista (Rodentia, Sciuridae) with the description of new material from the Gray Fossil Site (Tennessee)

Flying squirrels (Rodentia, Sciuridae, Sciurinae, Pteromyini) have a long and complex history in North America. First recorded during the Late Eocene, they vanished during the early Late Miocene (at about 9 Ma) only to re-appear in the Pliocene and Pleistocene. The first flying squirrels to be recorded after this Late Miocene gap are surprisingly attributed to the Eurasian genus of giant flying squirrel Miopetaurista . These are just two specimens from Florida that purportedly belong to Miopetaurista webbi , an endemic species. In this work we review these occurrences and further describe a new specimen from the Early Pliocene (latest Hemphillian or early Blancan) Gray Fossil Site in Tennessee, which may represent the oldest record of the genus in North America. We validate their attribution to Miopetaurista webbi and found this species to be probably closely related to Miopetaurista thaleri , the only known Pliocene Eurasian species. The occurrence of Miopetaurista in eastern North America is puzzling, as it is set far away from the known geographical range of the genus and of that of its sister taxon, the extant Petaurista . We hypothesize that Miopetaurista , which was linked to warm forested environments, dispersed into North America via the Bering Land Bridge during the warm phases of the Early Pliocene in the frame of a major faunal dispersal involving many other taxa. Later climatic cooling isolated these squirrels in warmer refuges, such as Florida, until they finally became extinct during the Pleistocene.