''Dinohippus'' (

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

: "Terrible horse") is an extinct

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 ...

which was endemic to

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

from the late

Hemphillian The Hemphillian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 10,300,000 to 4,900,000 years BP. It is usually considered ...

stage of the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

through the

Zanclean The Zanclean is the lowest stage or earliest age on the geologic time scale of the Pliocene. It spans the time between 5.332 ± 0.005 Ma (million years ago) and 3.6 ± 0.005 Ma. It is preceded by the Messinian Age of the Miocene Epoch, and fol ...

stage of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58mya Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...

) and in existence for approximately . Fossils are widespread throughout North America, being found at more than 30 sites from

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

and

Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...

(

Alajuela Formation The Alajuela Formation, originally Alhajuela Formation (Tau),Geologic Map, 1980 is a Miocene, Late Miocene (Tortonian, Hemphillian, Early Hemphillian or Clarendonian, Latest Clarendonian in the North American land mammal age, NALMA classification) ...

Taxonomy

Quinn originally referred ''"Pliohippus" mexicanus'' to ''Dinohippus'', but unpublished cladistic results in an SVP 2018 conference abstract suggest that ''mexicanus'' is instead more closely related to extant horses than to ''Dinohippus''.

Description

''Dinohippus'' was the most common horse in North America and like ''

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 ...

'', it did not have a dished face. It has a distinctive passive " stay apparatus" formed from bones and tendons to help it conserve energy while standing for long periods. ''Dinohippus'' was the first horse to show a rudimentary form of this character, providing additional evidence of the close relationship between ''Dinohippus'' and ''Equus''. ''Dinohippus'' was originally thought to be a

monodactyl In biology, dactyly is the arrangement of wikt:digit, digits (fingers and toes) on the hands, feet, or sometimes wings of a tetrapod animal. It comes from the Greek (language), Greek word δακτυλος (''dáktylos'') = "finger". Sometimes t ...

horse, but a 1981 fossil find in Nebraska shows that some were tridactyl. The species ''D. leidyanus'' had an estimated body mass of approximately .M. Mendoza, C. M. Janis, and P. Palmqvist. 2006. Estimating the body mass of extinct ungulates: a study on the use of multiple regression. Journal of Zoology Dinohippus leidyanus foot bones

References

{{Taxonbar, from=Q252178 Miocene horses Miocene odd-toed ungulates Pliocene horses Prehistoric placental genera Messinian life Tortonian life Piacenzian extinctions Miocene mammals of North America Pliocene mammals of North America Blancan Hemphillian Neogene Costa Rica Fossils of Costa Rica Neogene Mexico Fossils of Mexico Neogene Panama Fossils of Panama Neogene United States Fossils of the United States Fossil taxa described in 1955