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Equidae
Equidae is the family of horse-like animals, which belong to the order Perissodactyla. It is sometimes known as the horse family. Apart from the horse, other extant equids include assorted subspecies of donkey or ass, and the zebras. All of these are in the genus Equus.
CharacteristicsEquids are medium to large mammals, with long heads, and necks with a mane. Their legs are slender and end in a single, unguligrade toe, protected by a horny hoof. They have long, slender, tails, either ending in a tuft, or entirely covered in flowing hair. They are adapted to generally open terrain, from plains and savannas, to mountains or deserts. 
The range of equid monocular vision. Shaded areas represent blind spots. Equids are herbivores, and feed predominantly on tough, fibrous food, such as grasses and sedges. When in need, they will also eat other vegetable matter, such as leaves, fruits, or bark, but are normally grazers, not browsers. Unlike ruminants, with their complex stomachs, equids break down cellulose in the "hindgut" or cecum, a part of the colon. Their dentition is almost complete, with cutting incisors to crop food, and grinding molars set well back behind a diastema. The dental formula for equids is: 
A feral horse herd in the western United States Females, usually called mares in horses and zebras, or, in the case of asses and donkeys, jennys, usually bear a single foal, after a gestation period of approximately 11 months. Young equids are able to walk within an hour of birth, and are weaned after four to thirteen months (animals living in the wild naturally wean foals at a later date than those under domestication). Depending on species, living conditions and other factors, females in the wild may give birth every year or every other year.[1][2] Equids who are not in foal generally have a seasonal estrous cycle, from early spring into autumn. Most females enter an anestrus period during the winter and thus do not cycle in this period. The reproductive cycle is controlled by the photoperiod (length of the day), with estrus triggered when the days begin to lengthen. Anestrus prevents the female from conceiving in the winter months, as that would result in her foaling during the harshest part of the year, a time when it would be more difficult for the foal to survive.[3] However, equids who live near the equator, where there is less change in length of day from season to season, have no anestrus period, at least in theory.[4] Further, for reasons that are not clear, about twenty percent of domestic mares in the Northern Hemisphere will cycle the year round.[5] Evolution
Hyracotherium, also called "eohippus". The group became relatively large during the Miocene, with many new species appearing. By this time, equids were more truly horse-like, having developed the typical body shape of the modern animals. Many of these species bore the main weight of their bodies on their central, third, toe, with the others becoming reduced, and barely touching the ground, if at all. The surviving modern genus, Equus, had evolved by the early Pleistocene, and spread rapidly though the world.[7] Classification
Przewalski's horse, the only remaining type of "wild" horse that has never been domesticated 
A domesticated horse 
A donkey 
An onager, one type of wild ass 
A pair of Kiangs 
Plains zebra
Cross-breedsDifferent species of equidae can crossbreed, though the ensuing offspring are usually infertile. Some hybrid equidae include: 
a mule
Any equid with partial zebra ancestry is also called a zebroid. See alsoReferencesSources
an:Equidae bg:???? ca:Èquid cs:Ko?ovití da:Hestefamilien de:Pferde et:Hobuslased el:??????? es:Equidae eo:Ekvedoj fr:Equus (genre) gl:Équido ko:?? hr:Konji id:Equidae it:Equus he:?????? la:Equidae lb:Päerd lt:Arkliai lij:Equus hu:Lófélék nl:Paardachtigen ja:??? no:Hester oc:Equidae pl:Koniowate pt:Equus ro:Equidae ru:?????? simple:Equidae sk:Equus (rod) sr:???? fi:Hevoseläimet sv:Hästdjur ta:???????? ??????? vi:H? Ng?a tr:Atgiller zh:?? Source: Wikipedia | The above article is available under the GNU FDL. | Edit this article
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