Protohippus

Protohippus is an extinct three-toed genus of horse.^[3] It was roughly the size of a modern donkey. Fossil evidence suggests that it lived during the Late Miocene (Clarendonian to Hemphillian), from about 13.6 Ma to 5.3 Ma.^[4]

Protohippus Temporal range: Clarendonian-Hemphillian ~13.6–5.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Protohippus simus skeleton
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Perissodactyla
Family:	Equidae
Subfamily:	Equinae
Tribe:	Equini
Genus:	†Protohippus Leidy, 1858[1][2]
Type species
Equus (Protohippus) perditus Leidy, 1858

Analysis of Protohippus' skull and teeth suggests that it is most closely related to the genus Calippus.^[4]

Fetus

Skull

P. simus. This animal died from a breech birth, where the hind feet instead of the head of the foal emerges first. As the foal did not fully emerge, infection may have ensued, killing the mother. From Cherry County, Nebraska. At the AMNH.

Protohippus foot.

Species

• P. vetus
• P. perditus
• P. supremus (also P. simus)
• P. gidleyi

See also

• Eohippus
• Mesohippus