Uintaceras fossil map
Where fossils of Uintaceras have been found, shown on the Earth as it looked about 45 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 45 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 | 45.9–39.7 million years ago (Lutetian to Bartonian) |
| Periods | Paleogene |
| Family | Rhinocerotidae |
| Named by | Holbrook and Lucas 1997 |
| Fossil records | 4 occurrences at 2 locations (PBDB) |
| Found in | United States |
| Rock formations | Uinta, Washakie |
About Uintaceras
Uintaceras is an extinct genus of medium-sized early rhinocerotoids that lived in North America (Wyoming and Utah) during the Middle Eocene, with only the type species U. radinskyi, named in 1997, currently contained within the genus. Traditionally considered the oldest and most primitive species of the Rhinocerotidae, it may instead have been a close relative of the Asian Paraceratheriidae. The dubious species Forstercooperia (Hyrachyus) grandis (Radinsky, 1967; Peterson, 1919) is also possibly the same animal as Uintaceras, although the Asian material of F. grandis was assignable to Forstercooperia confluens.
Uintaceras weighed about 220 kilograms (490 lb) when fully grown. It was a relatively slender animal and Uintaceras resembled a typical hyracodontid (e.g. Hyracodon), but differed from the hyracodonts due to the presence of a primitive four-fingered hand and a number of other features of the structure of the legs, which were clearly not intended for fast and long running.
Text in “About” is quoted from the Wikipedia article Uintaceras (revision 1369645097), 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: Q2474277.
