Three perissodactyl species (clockwise from left): plains zebra (Equus quagga), Indian rhinoceros (Rhinoceros unicornis) and South American tapir (Tapirus terrestris)

Perissodactyla is an order of placental mammals composed of odd-toed ungulates – hooved animals which bear weight on one or three of their five toes with the other toes either present, absent, vestigial, or pointing backwards. Members of this order are called perissodactyls, and include rhinoceroses, tapirs, and horses. They are primarily found in Africa, southern and southeastern Asia, and Central America, and are found in a variety of biomes, most typically grassland, savanna, inland wetlands, shrubland, and desert. Perissodactyls range in size from the 1.8 m (6 ft) long Baird's tapir to the 4 m (13 ft) long white rhinoceros. Over 50 million domesticated donkeys and 58 million horses are used in farming worldwide, while four species of perissodactyl have potentially fewer than 200 members remaining. Three subspecies of the black rhinoceros, the Syrian wild ass subspecies of the onager, and the tarpan subspecies of the wild horse have gone extinct in the last 200 years.

The eighteen extant species of Perissodactyla are divided into two suborders: Ceratomorpha, containing the families Rhinocerotidae and Tapiridae, and Hippomorpha, containing the family Equidae. Rhinocerotidae contains five species of rhinoceroses split into four genera, Tapiridae contains four species of tapir in a single genus, and Equidae contains nine species in a single genus, including horses, donkeys, and zebras. Over 75 extinct Perissodactyla species have been discovered, though due to ongoing research and discoveries the exact number and categorization is not fixed.^[1]

Conventions

Conservation status codes listed follow the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Range maps are provided wherever possible; if a range map is not available, a description of the bovid's range is provided. Ranges are based on the IUCN Red List for that species unless otherwise noted. All extinct species or subspecies listed alongside extant species went extinct after 1500 CE, and are indicated by a dagger symbol "†".

Classification

The order Perissodactyla consists of two suborders, Ceratomorpha and Hippomorpha. Ceratomorpha contains the five species in four genera of the Rhinocerotidae family as well as the five species in one genera of the Tapiridae family. Hippomorpha contains a single family, Equidae, in turn containing nine species in a single genus. Many of these species are further subdivided into subspecies. This does not include hybrid species such as the mule, hinny, or zebroid, or extinct prehistoric species. Several perissodactyla subspecies have gone extinct in modern times, namely the southern black rhinoceros, north-eastern black rhinoceros, and western black rhinoceros subspecies of the black rhinoceros, the Syrian wild ass subspecies of the onager, and the tarpan subspecies of the wild horse.

Perissodactyls

The following classification is based on the taxonomy described by Mammal Species of the World (2005), with augmentation by generally accepted proposals made since using molecular phylogenetic analysis.^[2]

Suborder Ceratomorpha

Rhinocerotidae

Main article: Rhinocerotidae

Genus Ceratotherium – Gray, 1868 – one species

Common name	Scientific name and subspecies	Range	Size and ecology	IUCN status and estimated population
White rhinoceros	C. simum (Burchell, 1817) Two subspecies C. s. cottoni (Northern white rhinoceros) C. s. simum (Southern white rhinoceros)	Central and southern Africa (Northern subspecies in orange)	Size: 370–400 cm (146–157 in) long, plus 28 cm (11 in) tail[3] Habitat: Savanna, shrubland, and grassland[4] Diet: Grass[3]	NT  10,000 [4]

Genus Dicerorhinus – Gloger, 1841 – one species

Common name	Scientific name and subspecies	Range	Size and ecology	IUCN status and estimated population
Sumatran rhinoceros	D. sumatrensis (Fischer von Waldheim, 1814) Three subspecies D. s. harrissoni (Bornean rhinoceros) D. s. lasiotis (Northern Sumatran rhinoceros) D. s. sumatrensis (Western Sumatran rhinoceros)	Scattered Sumatra and Borneo (former range in orange)	Size: 236–318 cm (93–125 in) long[5] Habitat: Forest[6] Diet: Twigs, leaves, fruit, and shoots[7]	CR  30 [6]

Genus Diceros – Gray, 1821 – one species

Common name	Scientific name and subspecies	Range	Size and ecology	IUCN status and estimated population
Black rhinoceros	D. bicornis (Linnaeus, 1758) Eight subspecies D. b. bicornis (Southern black rhinoceros)† D. b. brucii (North-eastern black rhinoceros)† D. b. chobiensis (Chobe black rhinoceros) D. b. ladoensis (Uganda black rhinoceros) D. b. longipes (Western black rhinoceros)† D. b. michaeli (Eastern black rhinoceros) D. b. minor (South-central black rhinoceros) D. b. occidentalis (South-western black rhinoceros)	Southern Africa (extant in green, reintroduced extant in yellow, former range in red)	Size: 290–310 cm (114–122 in) long, plus 60 cm (24 in) tail[3] Habitat: Savanna, shrubland, and desert[8] Diet: Twigs, woody shrubs, small trees, legumes, and grass[9]	CR  3,100 [8]

Genus Rhinoceros – Linnaeus, 1758 – two species

Common name	Scientific name and subspecies	Range	Size and ecology	IUCN status and estimated population
Indian rhinoceros	R. unicornis Linnaeus, 1758	Scattered northern Indian subcontinent	Size: 330–350 cm (130–138 in) long, plus 66 cm (26 in) tail[7] Habitat: Forest, grassland, and inland wetlands[10] Diet: Grass, fruit, leaves, branches, aquatic plants, and cultivated crops[11]	VU  2,100–2,200 [10]
Javan rhinoceros	R. sondaicus Desmarest, 1822 Three subspecies R. s. annamiticus (Vietnamese Javan rhinoceros) R. s. inermis (Lesser Indian rhinoceros) R. s. sondaicus (Indonesian Javan rhinoceros)	Western tip of Java (former range in orange)	Size: 300–350 cm (118–138 in) long[7] Habitat: Forest[12] Diet: Bamboo as well as parts of fig trees and guest trees[13]	CR  18 [12]

Tapiridae

Main article: Tapiridae

Genus Tapirus – Brisson, 1762 – four species

Common name	Scientific name and subspecies	Range	Size and ecology	IUCN status and estimated population
Baird's tapir	T. bairdii (Gill, 1865)	Central America	Size: 180–250 cm (71–98 in) long, plus 5–13 cm (2–5 in) tail[14] Habitat: Forest, shrubland, grassland, and inland wetlands[15] Diet: Leaves as well as fruit, twigs, flowers, sedges, and grass[14]	EN  Unknown [15]
Malayan tapir	T. indicus (Desmarest, 1819) Two subspecies T. i. brevetianus T. i. indicus	Scattered southeastern Asia	Size: 250–300 cm (98–118 in) long, plus up to 10 cm (4 in) tail[16] Habitat: Forest, grassland, and inland wetlands[17] Diet: Leaves, buds, growing twigs, bark, herbs, low growing succulents, shrubs, fruit, club moss, grass, tubers, and aquatic plants[18]	EN  2,500 [17]
Mountain tapir	T. pinchaque (Roulin, 1829)	Andes mountains in northwestern South America	Size: 180–200 cm (71–79 in) long, plus up to 10 cm (4 in) tail[16] Habitat: Forest, shrubland, grassland, and inland wetlands[19] Diet: Shrub leaves[20]	EN  2,500 [19]
South American tapir	T. terrestris (Linnaeus, 1758) Four subspecies T. t. aenigmaticus T. t. colombianus T. t. spegazzinii T. t. terrestris	Northern and eastern South America	Size: 190–240 cm (75–94 in) long, plus up to 10 cm (4 in) tail[16] Habitat: Forest, savanna, shrubland, grassland, and inland wetlands[21] Diet: Fruit, leaves, and other plant material[22]	VU  Unknown [21]

Suborder Hippomorpha

Equidae

Main article: Equidae

Genus Equus – Linnaeus, 1758 – nine species

Common name	Scientific name and subspecies	Range	Size and ecology	IUCN status and estimated population
African wild ass	E. africanus (Heuglin, Fitzinger, 1866) Two subspecies E. a. africanus (Nubian wild ass) E. a. somalicus (Somali wild ass)	Scattered northeastern Africa	Size: 230–250 cm (91–98 in) long, plus 40–45 cm (16–18 in) tail[23] Habitat: Shrubland, grassland, and desert[24] Diet: Grass as well as shrubs[24]	CR  20–200 [24]
Donkey	E. asinus Linnaeus, 1758	Worldwide	Size: 190–200 in (4,826–5,080 mm) long, plus 40–50 cm (16–20 in) tail[25] Habitat: Desert[26] Diet: Grass, as well as shrubs and desert plants[26]	NE  Unknown (about 50.4 million used in farming, not including 8.5 million mules)[27]
Grévy's zebra	E. grevyi Oustalet, 1882	Scattered eastern Africa	Size: 250–300 cm (98–118 in) long, plus 38–60 cm (15–24 in) tail[28] Habitat: Shrubland and grassland[29] Diet: Grass[28]	EN  2,000 [29]
Horse	E. caballus Linnaeus, 1758	Worldwide	Size: 220–280 cm (87–110 in) long[30] Habitat: Grassland, savanna, inland wetlands, and shrubland Diet: Grains, grass, and shrubs[30]	NE  Unknown (58 million used in farming)[31]
Kiang	E. kiang Moorcroft, 1841 Three subspecies E. k. holdereri (Eastern kiang) E. k. kiang (Western kiang) E. k. polyodon (Southern kiang)	Central Asia	Size: 182–214 in (4,623–5,436 mm) long, plus 32–45 cm (13–18 in) tail[32] Habitat: Shrubland, grassland, and desert[33] Diet: Grass as well as sedges[33]	LC  60,000–70,000 [33]
Mountain zebra	E. zebra Linnaeus, 1758 Two subspecies E. z. hartmannae (Hartmann's mountain zebra) E. z. zebra (Cape mountain zebra)	Scattered southern Africa	Size: 210–260 cm (83–102 in) long, plus 40–55 cm (16–22 in) tail[34] Habitat: Savanna, shrubland, and grassland[35] Diet: Grass[35]	VU  35,000 [35]
Onager	E. hemionus Pallas, 1775 Five subspecies E. h. hemionus (Mongolian wild ass) E. h. hemippus (Syrian wild ass)† E. h. khur (Indian wild ass) E. h. kulan (Turkmenian kulan) E. h. onager (Persian onager)	Central Asia and scattered western Asia	Size: 200–250 cm (79–98 in) long, plus 30–49 cm (12–19 in) tail[28] Habitat: Savanna, shrubland, grassland, and desert[36] Diet: Grass and succulent plants[28]	NT  28,000 [36]
Plains zebra	E. quagga Boddaert, 1785	Southern and southeastern Africa	Size: 220–250 cm (87–98 in) long, plus 47–56 cm (19–22 in) tail[28] Habitat: Savanna, shrubland, and grassland[37] Diet: Grass, as well as leaves and buds[28]	NT  150,000–250,000 [37]
Wild horse	E. ferus Boddaert, 1785 Two subspecies E. f. ferus (Tarpan)† E. f. przewalskii (Przewalski's horse)	Central Asia	Size: 220–260 cm (87–102 in) long, plus 80–110 cm (31–43 in) tail[28] Habitat: Grassland and desert[38] Diet: Grass, leaves, and buds[28]	EN  200 [38]

References

Sources