Pteromyinae

a subfamily of rodents of the family Sciuridae, commonly called flying squirrels; they are frequently distinguished as a separate family.

In contrast to true squirrels, flying squirrels have loose membranes extending from the sides of the body to the limbs, which permit the animals to glide. Body length, up to 60 cm; tail, up to 40 cm. The fine thick fur is grayish or brownish. There are ten or 12 genera comprising about 30 species.

Flying squirrels live in forests of the temperate zone throughout the northern hemisphere and in the tropical zones of Asia. There is one species, Pteromys volans, in the USSR; it inhabits mixed forests and, beyond the Urals, forest steppes. The squirrels are active throughout the year, leaping easily from tree to tree and gliding over distances reaching 50 m. They feed on the buds, leaves, and roots of deciduous trees primarily, but also of pines and larches. They live in tree hollows and apparently bear a single litter annually of three or four young. The first fossil remains are from the Miocene period.