Palaeosyops fossil map
Where fossils of Palaeosyops 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 | 56–45.9 million years ago (Ypresian to Lutetian) |
| Periods | Paleogene |
| Family | Brontotheriidae |
| Named by | Leidy 1870 |
| Fossil records | 130 occurrences at 16 locations (PBDB) |
| Found in | United States |
| Rock formations | Bridger, Huerfano, Wasatch, Aycross, Green River, Willwood |
About Palaeosyops
Palaeosyops (lit. 'ancient boar face') is an extinct genus of primitive brontothere that lived in Asia and North America during the Early to Middle Eocene. Palaeosyops was among the first brontotheres to be described scientifically, and is known from a large number of fossils, particularly from the Bridger Formation in the Green River Basin in the western United States.
The largest Palaeosyops were about the size of small cattle, exceeding 400 kilograms (880 lb) in weight. Palaeosyops was the largest mammal in its environment, and markedly larger in size than its ancestors and the more basal brontothere Eotitanops. Palaeosyops had a relatively robust skull, and is unique among the brontotheres for its quite extreme brachycephaly (a short and broad head). Gracile Palaeosyops skulls were once classified as the separate genus Limnohyops, but are now interpreted as showing sexually dimorphic differences. The dentition, overall anatomy, and inferred paleoenvironment (semitropical forests) of Palaeosyops all indicate that it had a diet and lifestyle similar to modern-day tapirs, though unlike tapirs Palaeosyops did not have a prehensile upper lip.
Text in “About” is quoted from the Wikipedia article Palaeosyops (revision 1376825638), 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: Q149549.
