Temporal range: Early Eocene - present
Spaulding et al., 2009
Ruminantia is a taxon within the order Artiodactyla that includes many of the well-known large grazing or browsing mammals: among them cattle, goats, sheep, deer, and antelope. All members of the Ruminantia employ foregut fermentation and are ruminants: they digest food in two steps, chewing and swallowing in the normal way to begin with, and then regurgitating the semidigested cud to rechew it and thus extract the maximum possible food value.
Ruminantiamorpha is a total clade of artiodactyls defined, according to Spaulding et al., as "Ruminantia plus all extinct taxa more closely related to extant members of Ruminantia than to any other living species." Spaulding grouped some genera of the family Anthracotheriidae within Ruminantiamorpha (but not in Ruminantia), but placed others within Ruminantiamorpha's sister clade, Cetancodontamorpha.
Not all ruminants belong to the Ruminantia.[verification needed]Tylopoda (such as camels, which chew a cud) and Hippopotamidae (such as hippopotami, which do not chew a cud) are classified as pseudoruminants. A number of other large grazing mammals, e.g. horses and kangaroos, employ hindgut fermentation as an adaptation for surviving on large quantities of low-grade food.