Perissodactyla is an

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

of placental

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s 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 The Baird's tapir (''Tapirus bairdii''), also known as the Central American tapir, is a species of tapir native to Mexico, Central America, and northwestern South America. It is the largest of the three species of tapir native to the Americas, as ...

to the 4 m (13 ft) long white rhinoceros. Over 50 million domesticated

donkey The domestic donkey is a hoofed mammal in the family Equidae, the same family as the horse. It derives from the African wild ass, ''Equus africanus'', and may be classified either as a subspecies thereof, ''Equus africanus asinus'', or as a ...

s 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 A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species ...

and

Tapiridae Tapirs ( ) are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South and Central America, with one species inhabi ...

, and Hippomorpha, containing the family Equidae. Rhinocerotidae contains five species of rhinoceroses split into four

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

, 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.

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 Hybrid speciation is a form of speciation where hybridization between two different species leads to a new species, reproductively isolated from the parent species. Previously, reproductive isolation between two species and their parents was tho ...

such as the

mule The mule is a domestic equine hybrid between a donkey and a horse. It is the offspring of a male donkey (a jack) and a female horse (a mare). The horse and the donkey are different species, with different numbers of chromosomes; of the two pos ...

, hinny, or zebroid, or extinct prehistoric species. Several perissodactyla subspecies have gone extinct in modern times, namely the

southern black rhinoceros The southern black rhinoceros, southern hook-lipped rhinoceros or Cape rhinoceros (''Diceros bicornis bicornis'') is an extinct subspecies of the black rhinoceros that was once abundant in South Africa from the Cape Province to Transvaal, southern ...

, 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. Suborder Ceratomorpha * Family

(rhinoceros) ** ''

Ceratotherium ''Ceratotherium'' (Greek: "horn" (keratos), "beast" (therion)) is a genus of the family Rhinocerotidae, consisting of a single extant species, the white rhinoceros The white rhinoceros, white rhino or square-lipped rhinoceros (''Ceratotherium ...

'': 1 species ** '' Dicerorhinus'': 1 species ** ''

Diceros ''Diceros'' (Greek: "two" (dio), "horn" (keratos)) is a genus of rhinoceros containing the living black rhinoceros ''(Diceros bicornis)'' and at least one extinct species. Taxonomy ''Diceros'' is generally believed to have branched off from an ...

'': 1 species ** '' Rhinoceros'': 2 species * Family

(tapir) ** '' Tapirus'': 4 species Suborder Hippomorpha * Family Equidae (horse, donkey, zebra) ** ''

Equus Equus may refer to: * ''Equus'' (genus), a genus of animals including horses, donkeys and zebras * ''Equus'' (play), a play by Peter Shaffer * ''Equus'' (film), a film adaptation of the Peter Shaffer play * Equus (comics), a comic book characte ...

'': 9 species

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.

Conventions

Classification

Perissodactyls

Suborder Ceratomorpha

Rhinocerotidae

Tapiridae

Suborder Hippomorpha

Equidae

References

Sources