''Protohippus'' is an extinct three-toed
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...
.
It was roughly the size of a modern donkey. Fossil evidence suggests that it lived during the Late Miocene (
Clarendonian
The Clarendonian 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 13,600,000 to 10,300,000 years BP, a period of .
It is u ...
to
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 ...
), from about 13.6 Ma to 5.3 Ma.
Analysis of ''Protohippus'' skull and teeth suggests that it is most closely related to the genus ''
Calippus''.
Species include:
* ''P. vetus''
* ''P. perditus''
* ''P. supremus'' (also ''P. simus'')
* ''P. gidleyi''
See also
* ''
Eohippus
''Eohippus'' is an extinct genus of small equid ungulates. The only species is ''E. angustidens'', which was long considered a species of ''Hyracotherium''. Its remains have been identified in North America and date to the Early Eocene (Ypresian ...
''
* ''
Mesohippus
''Mesohippus'' (Greek: / meaning "middle" and / meaning "horse") is an extinct genus of early horse. It lived 37 to 32 million years ago in the Early Oligocene. Like many fossil horses, ''Mesohippus'' was common in North America. Its shoulder hei ...
''
References
{{Taxonbar, from=Q3408120
Miocene horses
Prehistoric placental genera
Miocene mammals of North America
Clarendonian
Hemphillian
Fossil taxa described in 1858
Taxa named by Joseph Leidy