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''Orohippus'' (from the Greek , 'mountain' and , 'horse') is an extinct 
It is believed to have evolved from equids such as '' Eohippus'', as the earliest evidence for ''Orohippus'' appears about 2 million years after the first appearance of ''Eohippus''. The anatomical differences between the two are slight: they were the same size, but ''Orohippus'' had a slimmer body, a more elongated head, slimmer forelimbs and longer hind legs, all of which are characteristics of a good jumper. Its teeth were brachydont in height, but the development of flattened surfaces and shearing lophs on their molars suggests they were more a browser than a
Orohippus, Index Fossils and the Tertiary
National Center for Science Education
Eocene horses Eocene odd-toed ungulates Eocene mammals of North America Paleogene United States Prehistoric placental genera Extinct mammals of North America Eocene genus first appearances Eocene genus extinctions Fossil taxa described in 1872 {{horse-stub
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 ...
that lived in the Eocene (about 50 million years ago).
It is believed to have evolved from equids such as '' Eohippus'', as the earliest evidence for ''Orohippus'' appears about 2 million years after the first appearance of ''Eohippus''. The anatomical differences between the two are slight: they were the same size, but ''Orohippus'' had a slimmer body, a more elongated head, slimmer forelimbs and longer hind legs, all of which are characteristics of a good jumper. Its teeth were brachydont in height, but the development of flattened surfaces and shearing lophs on their molars suggests they were more a browser than a frugivore
A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance an ...
.Kitts, D. B. 1957. A Revision of the Genus Orohippus (Perissodactyla, Equidae). American Museum Novelties, 1864:1–40. The outer toes of ''Eohippus'' are no longer present in ''Orohippus'', hence on each forelimb there were four fingers (toes) and on each hind leg three toes.
Species of ''Orohippus'' has also been referred to ''Protorohippus
''Protorohippus'' (Latin: "before" (pro), + Greek: "mountain" (oros), "horse" (hippos)) is an extinct equid that lived in the Eocene of North America.
image:F John Series 2 Protorohippus card 5.jpg, left, Restoration
See also
* Evolution of th ...
''.
See also
* Evolution of the horse * HorseNotes
References
* MacFadden, B.J., 1998. Equidae. pp. 537–559 ''in'' C.M. Janis, K.M. Scott, and L.L. Jacobs (''eds.'') ''Evolution of Tertiary Mammals of North America'' Cambridge University Press, Cambridge.Orohippus, Index Fossils and the Tertiary
National Center for Science Education
Eocene horses Eocene odd-toed ungulates Eocene mammals of North America Paleogene United States Prehistoric placental genera Extinct mammals of North America Eocene genus first appearances Eocene genus extinctions Fossil taxa described in 1872 {{horse-stub