Eobasileus fossil map
Where fossils of Eobasileus 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 | Uintatheriidae |
| Named by | Cope 1872 |
| Fossil records | 10 occurrences at 3 locations (PBDB) |
| Found in | United States |
| Rock formations | Uinta, Washakie |
About Eobasileus
Eobasileus ("dawn-king") is a genus of dinoceratan mammal in the family Uintatheriidae. One species is currently considered valid, E. cornutus, though it has been suggested that the closely related Tetheopsis may also belong to this genus. The first specimen of Eobasileus, consisting of a skull, several vertebrae, and bones associated with the limbs, was collected from Haystack Mountain, from strata belonging to the Washakie Formation. The species became the subject of various letters written by Edward Drinker Cope (its describer) and Othniel Charles Marsh, and their disagreements over its taxonomy and anatomy contributed to the beginning of the Bone Wars.
Text in “About” is quoted from the Wikipedia article Eobasileus (revision 1370052435), 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: Q137787.
