Cows, Goats and Sheep
Cows, goats, sheep and antelopes (Family Bovidae) are also ungulates with an even number of toes, two on each foot touching the ground and two vestigial toes that do not contact the ground. They are ruminants, which means that they have stomachs with multiple chambers (four), which allows them to chew, digest, regurgitate and chew their food some more. Compared with other ruminants, these animal have true horns on their heads. Horns consist of a bone core covered with a keratin outer layer. These horns are permanent, never shed. This group includes about 146 species.
Cows are classified as bovines (SubFamily Bovinae), while goats and sheep are classified as caprines (SubFamily Caprinae). Various types of bovines include domestic cows, African buffalo, water buffalo, and American bison. The animal called a muskox is actually a caprine, more closely related to goats than cows. Thus, goats and sheep are related closely.
The antelopes belong to several SubFamilies in this group. Some, such as elands, kudus, sitatunga and bushbucks are very closely related to the cows and belong to the same SubFamily. They typically have spiraled horns. The true antelopes (SubFamily Antilopinae) include the springbok and several small antelopes such as the steenbok and dik-dik. Various antelopes can be identified by the unique shapes of their horns. Impalas (SubFamily Aepycerotinae) have tall horns, while waterbucks and kob (SubFamily Reduncinae) have horns that curve. Duikers (SubFamily Cephalophinae) have crests on their heads. Their close relatives, the wildebeest, hartebeest and topi (SubFamily Alcephalopinae) have shorter, bowed horns. The grazing antelopes such as the oryx, sable antelope and addax (SubFamily Hippotraginae) have bodies with a shape reminiscent of horses and very long horns.
Pronghorns are also shown here. Sometimes mistakenly called antelopes, the pronghorn has its own family (Family Antilocapridae). There used to be many more species of pronghorns with varying numbers of spiky projections on their heads, but the pronghorn in western North America is now the only living member of the family. The projections on their heads are also called a “pronghorn”. Those consist of a bony core like the cows and goats. However, the outer layer of keratin is shed and regrown every year, not permanent, which makes the pronghorns unique compared with the bovines.