Odd-toed ungulate

Odd-toed ungulates are the Perissodactyla, an order of mammals.

Odd-toed ungulates Temporal range: Late Palaeocene – Recent
Rhinoceros
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Eutheria
Superorder:	Laurasiatheria
Order:	Perissodactyla Owen, 1848

Odd-toed ungulates have an uneven number of toes: Horses have only one toe, rhinoceros have three toes, and tapirs have four toes on the front feet and three toes on the hind feet.

Their digestive system is more basic than the even-toed ungulates. A key difference between the two is that odd-toed ungulates digest plant cellulose in their intestines rather than in one or more stomach chambers as the even-toed ungulates do.

Horses, for example, get much less nutrition out of grass than bovines do. This has the consequence that horses have to stop and feed more often, which in turn makes them more liable to predators. However, horses are very well-adapted for running, more so than many oxen or other Artiodactyls.

The living ungulates are a much-reduced group: the horses (including zebras), the tapirs and the rhinoceros.

Taxonomy

• Order Perissodactyla
  • Family Rhinocerotidae
  • Family Tapiridae
  • Family Equidae

Odd-toed Ungulate Media

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  The white rhinoceros is the largest living perissodactyl

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  Tapirs are the only extant group of perissodactyls with a trunk.

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  Restriction of their habitat and poaching threaten the survival of most rhino species, including the Indian rhinoceros shown here

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  A young Brazilian tapir

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  Restoration of Palaeotherium, a palaeothere genus first formally described in 1804

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  Live reconstruction of chalicothere Anisodon grande (formerly Chalicotherium grande)

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  Eohippus, an early relative of the horse, is one of the oldest-known perissodactyls

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  Portrait of English anatomist and palaeontologist Richard Owen with the skull of a crocodile. Albumen print from wet collodion on glass negative, 1856.