They have two incisors in the upper and lower jaw which grow continually and must be kept short by gnawing.
The lagomorphs comprise two families, Leporidae (hares and rabbits), and Ochotonidae (pikas).
They differ from rodents in a number of physical characteristics, such as having four incisors in the upper jaw rather than two.
The bats' most distinguishing feature is that their forelimbs are developed as wings, making them the only mammals capable of flight.
There are about 220 artiodactyl species, including many that are of great economic importance to humans.