Pliohippus fossil map
Where fossils of Pliohippus have been found, shown on the Earth as it looked about 15 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 15 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Early mammals |
|---|---|
| Lived | 23.04–2.58 million years ago (Aquitanian to Piacenzian) |
| Periods | Neogene |
| Family | Equidae |
| Named by | Marsh 1874 |
| Fossil records | 314 occurrences at 68 locations (PBDB) |
| Found in | United States, Mexico |
| Rock formations | txn:42984, MR Caliente, Valentine, Ash Hollow, NS Caliente, Hungry Valley |
About Pliohippus
Pliohippus (from Ancient Greek πλείων (pleíon), meaning "more", and ἵππος (híppos), meaning "horse") is an extinct genus of Equidae, the horse family. Pliohippus arose in the middle Miocene, around 15 million years ago. The long and slim limbs of Pliohippus reveal a quick-footed steppe animal. While some specimens have one toe per leg, others have three (the main toe and two non-functional side toes).
Because of its many anatomical similarities, Pliohippus was initially believed to be the ancestor of the present-day horse and its relatives in Equus. Although Pliohippus clearly is an equid and thus related to Equus, its skull had deep facial fossae, a feature not found in any member of Equus. Additionally, its teeth were strongly curved, unlike the very straight teeth of modern horses. Consequently, it is unlikely to be the ancestor of the modern horse; instead, it is likely to be the ancestor of Astrohippus. Pliohippus stood approximately 1.25 metres, similar to the modern horse. Also like the modern horse, Pliohippus was a grazer that fed on steppe grasses of the North American plains it inhabited.
Text in “About” is quoted from the Wikipedia article Pliohippus (revision 1309948147), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 23 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q612924.
