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Dinohippus (Greek: "Terrible horse") is an extinct equid which was endemic to North America from the late Hemphillian stage of the Miocene through the Zanclean stage of the Pliocene (10.3—3.6 mya) and in existence for approximately 6.7 million years.[1][2] Fossils are widespread throughout North America, being found at more than 30 sites from Florida to Alberta and Panama (Alajuela Formation).

Dinohippus
Temporal range: Late Miocene-Late Pliocene
(Hemphillian-Blancan)
~10.3–3.6 Ma
Dinohippus leidyanus 3.JPG
Dinohippus leidyanus skeleton
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Equidae
Subfamily: Equinae
Tribe: Equini
Genus: Dinohippus
Quinn 1955
Type species
Pliohippus leidyanus
Species
  • D. edensis Frick 1924
  • D. interpolatus Cope 1893
  • D. leardi Drescher 1941
  • D. leidyanus Osborn 1918
  • D. mexicanus Lance 1950
  • D. osborni Frick 1924
  • D. pachyops Cope 1893
  • D. subvenus Quinn 1955

TaxonomyEdit

 
Skull

Quinn originally referred "Pliohippus" mexicanus to Dinohippus, but unpublished cladistic results in an SVP 2018 conference abstract suggest that mexicanus is instead more closely related to extant horses than to Dinohippus.[3]

DescriptionEdit

Dinohippus was the most common horse in North America and like Equus, 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.[4] Dinohippus was originally thought to be a monodactyl horse, but a 1981 fossil find in Nebraska shows that some were tridactyl.[5] The species D. leidyanus had an estimated body mass of approximately 200 kilograms (440 lb).[6]

 
Foot bones

ReferencesEdit

  1. ^ Paleobiology Database: Dinohippus basic info.
  2. ^ Bruce J. MacFadden: Cenozoic Mammalian Herbivores from the Americas: Reconstructing Ancient Diets and Terrestrial Communities. Annual Review of Ecology and Systematics, Vol. 31, (2000), pp. 33-59
  3. ^ http://vertpaleo.org/Annual-Meeting/Annual-Meeting-Home/SVP-2018-program-book-V4-FINAL-with-covers.aspx
  4. ^ Florida Museum of Natural History
  5. ^ Horse Ecology
  6. ^ 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