The postorbital processs are well developed, and the distance between the orbits is considerable. The jugals are long, and their anterior ends contact the frontals . The palate appears broad and relatively short, ending at about the same level as the molar row. Bullae are relatively large but not inflated. The remaining cheekteeth, which are always rooted, usually have well-developed transverse ridges.
Squirrels generally eat nuts and seeds, but fungi, insects and young birds are sometimes taken.
Ground squirrels eat mostly green plant material. Squirrels that live in temperate areas often cache or bury nuts and seeds for use during the winter. This caching behavior makes squirrels an important disperser of plant seeds, as buried seeds are often not found and may germinate. Many ground squirrels hibernate and some store food in underground burrows. Some northern species of squirrels are hunted for their soft, thick fur, and many of the larger species are hunted for food.