Named By: O. C. Marsh. - 1876.
Synonyms: Eohippus validus, Hyracotherium angustidens, H. a. angustidens, H. a. etsagicum, H. vasacciensis, H. v. vasacciensis, H. cusptidatum, H. seekinsi, H. loevii, Orohippus angustidens, Orohippus cuspidatus, Orohippus vasacciensis, Lophiotherium vasacciense.
Classification: Chordata, Mammalia, Perissodactyla, Equidae.
Species: E. angustidens (type).
Size: About 30 centimetres high at the shoulder.
Known locations: Mexico. USA.
Time period: Ypresian of the Eocene.
Fossil representation: Numerous individuals of varying levels of completeness.
is a classic prehistoric mammal, dubbed as one of the earliest and
smallest horses ever to live. There has in the past been some
taxonomic confusion over the validity of the genus, and at one time
Eohippus was actually regarded as belonging to
another genus named
Later thought has cast doubt upon the correctness of
such thinking, and now once again Eohippus is
regarded as being
distinct from Hyracotherium.
Eohippus was tiny, and most individuals seem to have averaged a size of about thirty centimetres high at the shoulder. Most early horses seem to have fed as browsers, selectively feeding upon low growing plants. Such an environment and small size would have meant that Eohippus could hide amongst the undergrowth to try and avoid the eyes of hungry predators such as creodonts and early nimravids.
- Notice of new Tertiary mammals. V. - American Journal of Science 12(71):401-404. - O. C. Marsh. - 1876.
- Quo vadis eohippus? The systematics and taxonomy of the early Eocene equids (Perissodactyla). - Zoological Journal of the Linnean Society. 134 (2): 141–256. - D. J. Froehlich - 2002.
- Fossil Horses--Evidence for Evolution. - B. J. MacFadden - 2005.