The systematic relationships of artiodactyls are still being worked out;
many early fossil artiodactyls are not easy to place in standard
classifications. Artiodactyls have traditionally been classified according to the scheme
outlined below.
- Palaeodonta
- Various primitive, extinct artiodactyl groups, mostly small in size. Includes the
oreodonts. This is almost certainly a paraphyletic assemblage.
- Suina
- Includes Suidae (pigs and warthogs), Tayassuidae (peccaries), and Hippopotamidae (hippopotami),
plus several extinct families. Characterized by a simple stomach, omnivorous diet, and relatively
unspecialized teeth. The giant hippopotamus is the only aquatic artiodactyl, spending most of its
time in water.
- Tylopoda
- Includes Camelidae (camels, llamas, alpacas, etc.) plus several extinct families. Extinct
members of the Tylopoda had small hooves, but in living camels the hooves have been lost and
replaced by pads. Living tylopods have a chambered stomach, albeit not as well developed as that
seen in the Pecora.
- Tragulina
- Includes two genera: Hyemoschus, the African chevrotain, and Tragulus, the Asian
"mouse deer." These are the smallest of all artiodactyls; the smallest species, the lesser Malay
mouse deer, is only 40 cm long no bigger than a rabbit.
- Pecora
- Includes most living artiodactyls, such as Giraffidae (giraffes and okapi), Cervidae (deer,
elk, caribou, etc.), Bovidae (cows, buffalo, sheep, goats, antelope), Moschidae (musk deer), and
Antilocapridae (American pronghorn "antelope" which is not a true antelope) Typical
pecorans have well-developed, four-chambered ruminant stomachs, and most have paired horns on
the head.
DeerNet, at the University of Alberta, has a
list
of living ungulates, including photographs. And be sure to check out The Ultimate Ungulate.
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