Ungulates are mammals with hooves. Reindeer, moose, elk, deer, horses, cows, sheep and pigs are examples of ungulates.Perissodactyls (Greek perissos-uneven, and dactylus-finger or digit) are ungulates with an odd numbers of toes and even-toed ungulates are called artiodactyls (Greek artio-even, and dactylus-finger or digit). Artiodactyls are the cloven-hoofed mammals.
Deer are artiodactyls more closely related to pigs than to perissodactyles such as horses, which, in turn, are more closely related to rhinos.
Both groups of ungulates first appeared in the Eocene, over 50,000,000 years ago. Fossils of the largest land mammal ever found were from Oligocene (35,000,000 yrs. ago) rhinos that approached 11 tons in weight and stood 19 feet at the shoulder.
