Squirrels belong to the family Sciuridae of small or medium-sized rodents. They are original from America, Eurasia, and Africa (although they first appeared 40 years ago in Eocene). Squirrels are not big animals, but there is a wide range of sizes along them: the smallest one is up to 10 cm on length and weights around 10g, and the biggest one can be up to 73cm of length and 8 kg of weight. Squirrels are herbivorous, although some of them eat small insects, and diurnal (except the flying squirrels).