A Miopetaurista (Sciuridae, Rodentia) cranium from the middle Miocene of Bavaria (Germany) and brain evolution in flying squirrels

Flying squirrels (Sciurinae, Pteromyini) are the most successful group of gliding mammals. However, their fossil record mostly consists of isolated dental remains which provide very limited insights into their paleobiology and evolution. Only recently, the first skeleton of a fossil flying squirrel, belonging to the species Miopetaurista neogrivensis, has been described. It presents all the diagnostic gliding-related postcranial features of its extant relatives and shows that this group has undergone very little morphological change for almost 12 million years. However, the associated cranium is badly crushed, so particular details of the cranial morphology cannot be described. Here we describe a well-preserved cranium of the closely-related Miopetaurista crusafonti from 12.5–12.0 Ma from Bavaria (Germany). Its cranial morphology is found to be almost identical to extant large flying squirrels, even in details such as the position of the foramina. The virtual endocast also shows close a...