Hipparion

"Hipparion" in sensu lato The genus "Hipparion" was used for over a century as a form classification to describe over a hundred species of Holartic hipparionines from the Pliocene and Miocene eras that had three toes and isolated protocones. Since then, groups such as the genera Cormohipparion and Neohipparion were proposed to further sort these species, typically based on differences in skull morphology. These species are now known as "Hipparion" in sensu lato (s.l.), or a broad sense. Hipparion in sensu stricto Hipparion in sensu stricto (s.s.), or a strict sense, describes the genus of Old World hipparionines from remains found in Eurasia (France, Greece, Turkey, Iran, and China) from the Late Miocene era (~10-5 Ma, or million years ago). The assignment of remains from elsewhere to the genus, such as North America and Africa, is uncertain. ==Morphology==

Hipparion generally resembled a smaller version of the modern horse, but was tridactyl, or three-toed. It had two vestigial outer toes on each limb in addition to its hoof. Hipparion was typically medium in size, at about 1.4 m (4.6 ft) tall at the shoulder. The estimated body mass of Hipparion depends on the species, but ranges from about 135 to 200 kg (about 298 to 441 lbs). Hipparion had hypsodont dentition (high-crowned teeth) for its premolars and molars, with a crown height of about 60 mm (2.36 in). Hipparion had isolated protocones in the upper molars, meaning a cusp of the teeth called a protocone was not connected to a tooth crest called a protoloph. == Paleobiology and paleoecology ==

Hipparion lived in the Old World Savannah Biome, or OWSB, consisting of woodlands to grasslands.'' == Evolution and extinction ==

Hipparion likely evolved from a species of Cormohipparion during the Late Miocene, about 11.4–11.0 Ma. This species, C. occidentale, came to Eurasia and Africa from North America. In the Old World, Hipparion experienced population decline and extinction down a North to South gradient, as did many other Miocene vertebrates. This trend is believed to be due to environmental changes caused by global cooling and decreasing carbon dioxide levels in the atmosphere. == In culture ==

Bones and teeth of Hipparion were widely historically excavated in China as "dragon bones" to be used as ingredients in Traditional Chinese Medicine, under the belief the represented the remains of Chinese dragons. ==Species==