page_title: Even-toed ungulate
section_title: Limbs
hierarchical_section_title: Even-toed ungulate / Anatomy / Limbs
caption_attribution_description: English: Figure from Meyers Lexicon Conversion 1888 – Skeletons of mammalian hands. Hands of even-toed ungulates are highlighted. From left to right: Orangutan; Dog; Swine; Cattle; Tapir; Horse Abbreviations: R, Radius; U, Ulna; A-G, Cc, P, carpals; A, Scaphoideum; B, lunar; C, "Triquetum"; D, trapezium; E, trapezoids; F, Capitatum; G, Hamatum; P, Pisiform; Cc, central carpal; M, metacarpal; 1-5, thumb and digits two to five.
context_page_description: The even-toed ungulates are ungulates – hoofed animals – which bear weight equally on two of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing posteriorly. By contrast, odd-toed ungulates bear weight on one of the five toes: the third toe. Another difference between the two is that even-toed ungulates digest plant cellulose in one or more stomach chambers rather than in their intestine as the odd-toed ungulates do.
  The aquatic cetaceans evolved from even-toed ungulates, so modern taxonomic classification combines the two under the name Cetartiodactyla.
  The roughly 270 land-based even-toed ungulate species include pigs, peccaries, hippopotamuses, antelopes, mouse deer, deer, giraffes, camels, llamas, alpacas, sheep, goats, and cattle. Many of these are of great dietary, economic, and cultural importance to humans.
context_section_description: Even-toed ungulates bear their name because they have an even number of toes (two or four) – in some peccaries, the hind legs have a reduction in the number of toes to three. The central axis of the leg is between the third and fourth toe. The first toe is missing in modern artiodactyls, and can only be found in now-extinct genera. The second and fifth toes are adapted differently between species: 
  When camels have only two toes present, the claws are transformed into nails (while both are made of keratin, claws are curved and pointed while nails are flat and dull). These claws consist of three parts: the plate (top and sides), the sole (bottom), and the bale (rear). In general, the claws of the forelegs are wider and blunter than those of the hind legs, and the gape is farther apart. Aside from camels, all even-toed ungulates put just the tip of the foremost phalanx on the ground.
  In even-toed ungulates, the bones of the stylopodium (upper arm or thigh bone) and zygopodiums (tibia and fibula) are usually elongated. The muscles of the limbs are predominantly localized, which ensures that artiodactyls often have very slender legs. A clavicle is never present, and the scapula is very agile and swings back and forth for added mobility when running. The special construction of the legs causes the legs to be unable to rotate, which allows for greater stability when running at high speeds. In addition, many smaller artiodactyls have a very flexible body, contributing to their speed by increasing their stride length.
caption: Diagrams of hand skeletons of various mammals, left to right: orangutan, dog, pig, cow, tapir, and horse. Highlighted are the even-toed ungulates pig and cow.
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