''Pliohippus'' (Greek (, "more") and (, "horse")) is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of Equidae, the "horse family". ''Pliohippus'' arose in the middle Miocene, around 15 million years ago. The long and slim limbs of ''Pliohippus'' reveal a quick-footed

steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without trees apart from those near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the temperate grasslands, ...

animal. While some specimens have one toe per leg, others have three (the main toe and two non-functional side toes). Until recently, because of its many anatomical similarities, ''Pliohippus'' was believed to be the ancestor of the present-day horse and its relatives in ''

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 ...

''. Although ''Pliohippus'' clearly is an

equid Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus'', w ...

and thus related to ''Equus'', its skull had deep facial ''fossae'', a feature not found in any member of ''Equus''. Additionally, its teeth were strongly curved, unlike the very straight teeth of modern horses. Consequently, it is unlikely to be the ancestor of the modern horse; instead, it is likely to be the ancestor of '' Astrohippus''.MacFadden, B. J. (1984). "Astrohippus and Dinohippus". ''J. Vert. Paleon''. 4(2):273-283. ''Pliohippus'' stood approximately 1.25 metres, similar to the modern horse. Also like the modern horse, ''Pliohippus'' was a grazer that fed on steppe grasses of the North American plains it inhabited. Fossils of ''Pliohippus'' have been found at many late Miocene localities in Colorado, the Great Plains (Nebraska, including Ashfall Fossil Beds and the Dakotas) and also Canada. ''Pliohippus'' has been found beside '' Neohipparion''. File:Pliohippus 01.jpg, Specimen at American Museum of Natural History File:Pliohippus pernix Wikipedia Juandertal.jpg, Life reconstruction of P. pernix

References

{{Taxonbar, from=Q612924 Miocene horses Pliocene horses Prehistoric placental genera Transitional fossils Neogene mammals of North America Barstovian Clarendonian Hemphillian Fossil taxa described in 1874 Taxa named by Othniel Charles Marsh