Equidae is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. The family evolved more than 50 million years ago, in the Eocene epoch, from a small, multi-toed ungulate into larger, single-toed animals. All extant species are in the genus Equus, which originated in North America. Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families. It is more specifically grouped within the superfamily Equoidea, the only other family being the extinct Palaeotheriidae.
Perissodactyla, or odd-toed ungulates, is an order of ungulates. The order includes about 17 living species divided into three families: Equidae, Rhinocerotidae (rhinoceroses), and Tapiridae (tapirs). They typically have reduced the weight-bearing toes to three or one of the five original toes, though tapirs retain four toes on their front feet. The nonweight-bearing toes are either present, absent, vestigial, or positioned posteriorly. By contrast, artiodactyls bear most of their weight equally on four or two of the five toes: their third and fourth toes. Another difference between the two is that perissodactyls digest plant cellulose in their intestines, rather than in one or more stomach chambers as artiodactyls, with the exception of Suina, do.
The donkey or ass is a domesticated equine. It derives from the African wild ass, Equus africanus, and may be classified either as a subspecies thereof, Equus africanus asinus, or as a separate species, Equus asinus. It was domesticated in Africa some 5000–7000 years ago, and has been used mainly as a working animal since that time.
The onager (Equus hemionus), also known as hemione or Asiatic wild ass, is a species of the family Equidae native to Asia. A member of the subgenus Asinus, the onager was described and given its binomial name by German zoologist Peter Simon Pallas in 1775. Six subspecies have been recognized, two of which are extinct.
Equus is a genus of mammals in the family Equidae, which includes horses, asses, and zebras. Within the Equidae, Equus is the only recognized extant genus, comprising seven living species. Like Equidae more broadly, Equus has numerous extinct species known only from fossils. The genus originated in North America and dispersed into the Old World and South America during the Early and Middle Pleistocene. Equines are odd-toed ungulates with slender legs, long heads, relatively long necks, manes, and long tails. All species are herbivorous, and mostly grazers, with simpler digestive systems than ruminants but able to subsist on lower-quality vegetation.
The kiang is the largest of the Asinus subgenus. It is native to the Tibetan Plateau in Ladakh India, northern Pakistan, Tajikistan, China and northern Nepal. It inhabits montane grasslands and shrublands. Other common names for this species include Tibetan wild ass, khyang and gorkhar.
The Mongolian wild ass, also known as Mongolian khulan, is the nominate subspecies of the onager. It is found in southern Mongolia and northern China. It was previously found in eastern Kazakhstan and southern Siberia before being extirpated there through hunting. As of 2015, the Mongolian wild ass is listed as Near Threatened by the IUCN. Current population estimates are approximately 42,000 individuals in Mongolia and around 5,000 individuals in Northern China.
The African wild ass or African wild donkey is a wild member of the horse family, Equidae. This species is thought to be the ancestor of the domestic donkey, which is sometimes placed within the same species. They live in the deserts and other arid areas of the Horn of Africa, in Eritrea, Ethiopia and Somalia. It formerly had a wider range north and west into Sudan, Egypt, and Libya. It is Critically Endangered, with about 570 existing in the wild.
The European wild ass or hydruntine is an extinct equine from the Middle Pleistocene to Late Holocene of Europe and West Asia, and possibly North Africa. It is a member of the subgenus Asinus, and closely related to the living Asiatic wild ass. The specific epithet, hydruntinus, means from Otranto.
The Yotvata Hai-Bar Nature Reserve is a 3,000-acre (12 km2) breeding and reacclimation center administered by the Israel Nature Reserves & National Parks Authority, situated in the Southern Arava near Yotvata.
The Syrian wild ass, less commonly known as a hemippe, an achdari, or a Mesopotamian or Syrian onager, is an extinct subspecies of onager native to the Arabian Peninsula and surrounding areas. It ranged across present-day Iraq, Palestine, Israel, Iran, Jordan, Saudi Arabia, Syria, and Turkey.
The Indian wild ass, also called the Indian wild donkey, Indian onager or, in the local Gujarati language, Ghudkhur and Khur, is a subspecies of the onager native to South Asia.
The Atlas wild ass, also known as Algerian wild ass, is a purported extinct subspecies of the African wild ass that was once found across North Africa and parts of the Sahara.
The evolution of the horse, a mammal of the family Equidae, occurred over a geologic time scale of 50 million years, transforming the small, dog-sized, forest-dwelling Eohippus into the modern horse. Paleozoologists have been able to piece together a more complete outline of the evolutionary lineage of the modern horse than of any other animal. Much of this evolution took place in North America, where horses originated but became extinct about 10,000 years ago, before being reintroduced in the 15th century.
Feral donkeys were first brought to Australia as pack animals to replace horses, which had succumbed to native poisonous plants. Now numbering 5 million, they have been declared a pest, owing to their damage to vegetation and erosion of soil. Culling is mainly carried out by marksmen in helicopters, and experiments are being made in fertility control.
The Turkmenian kulan, also called Transcaspian wild ass, Turkmenistani onager or simply the kulan, is a subspecies of onager native to Central Asia. It was declared Endangered in 2016.
The Persian onager, also called the Persian wild ass or Persian zebra, is a subspecies of onager native to Iran. It is listed as Endangered, with no more than 600 individuals left in the wild.
The Badghyz and Karabil semi-desert ecoregion covers the hills north of the central mountain ranges of Afghanistan, southeast Turkmenistan, and portions of Uzbekistan and Tajikistan. The landscape has been described as "savannah-like" and reminiscent of Africa, with desert sedges (Carex) and stands of wild pistachio trees. The area supports high biodiversity and a number of rare and endemic species, such as the endangered Turkmenian kulan (Equus hemionus kulan).
