artiodactyls

Artiodactyls, or even-toed ungulates, are a diverse order of mammals defined by having an even number of toes on each foot. In most species the weight is borne by the third and fourth digits, while the other toes are reduced. This contrasts with the odd-toed ungulates (perissodactyls).

The order includes many familiar mammals, such as cattle, sheep, goats, antelopes, deer (Bovidae, Cervidae, and related families), camels and llamas (Camelidae), pigs and peccaries (Suidae and Tayassuidae), and the giraffe and its relatives (Giraffidae). Tragulids (chevrotains) represent some of the most primitive artiodactyls, and the pronghorn (Antilocapridae) is a notable North American lineage. Hippos are also artiodactyls by classification in many systems, and whales and dolphins are now considered close relatives within the broader clade Cetartiodactyla.

Artiodactyls are distributed worldwide and inhabit most ecosystems. They range in size from small chevrotains to large ungulates such as moose or bison. Their diets are largely herbivorous, though pigs are omnivorous. Many artiodactyls are ruminants, possessing a multi-chambered stomach that hosts microbial fermentation of plant material; this enables efficient extraction of nutrients from fibrous vegetation.

Fossil artiodactyls first appeared in the early Eocene, about 50 million years ago, and the group diversified through the Cenozoic into numerous lineages. Today, artiodactyls play major roles in ecosystems and human economies.