Mesohippus

Superregnum: Eukaryota
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Ordo: Perissodactyla
Familia: Equidae
Subfamilia: †Anchitheriinae
Genus: Mesohippus
Species: M. bairdi - M. barbouri - M. braquistylus - M. cuneatus - M. equiceps - M. exoletus - M. intermedius - M. longiceps - M. metulophus -M. montanensis - M. obliquidens - M. proteulophus

Name

Mesohippus Marsh, 1875

Synonyms

* Palaeotherium Leidy, 1850
* Anchitherium Leidy, 1852
* Miohippus Hay, 1902, in partim
* Pediohippus Schlaikjer, 1935, in partim

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Mesohippus (Greek: μεσο/meso meaning "middle" and ιππος/hippos meaning "horse") is an extinct genus of early horse. It lived some 40 to 30 million years ago from the late Eocene to the mid-Oligocene. Like many fossil horses, Mesohippus was common in North America.
Mesohippus had longer legs than its predecessor Hyracotherium and stood about 60 centimetres (10 h) tall. It had also lost a toe and stood predominantly on its middle toe, although the other two were also used.[1] The face of Mesohippus was longer and larger than earlier equids. It had a slight facial fossa, or depression, in the skull. The eyes were rounder, and were set wider apart and farther back than in Hyracotherium.
Mesohippus bairdii skull

Unlike earlier horses, its teeth contained a single gap behind the front teeth, where the bit now rests in the modern horse. In addition, it had another grinding tooth, making a total of six. Mesohippus was a browser that fed on tender twigs and fruit[1]. The cerebral hemisphere, or cranial cavity, was notably larger than that of its predecessors; its brain was similar to that of modern horses.

References

1. ^ a b Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 255. ISBN 1-84028-152-9.