Pachyaena fossil map
Where fossils of Pachyaena have been found, shown on the Earth as it looked about 56 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 56 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 | 61.66–37.71 million years ago (Selandian to Bartonian) |
| Periods | Paleogene |
| Family | Mesonychidae |
| Named by | Cope 1874 |
| Fossil records | 150 occurrences at 52 locations (PBDB) |
| Found in | United States, China, France, Canada, Mongolia, United Kingdom |
| Rock formations | Willwood, Wasatch, DeBeque, Nongshan, Vaugirard, San Jose |
About Pachyaena
Pachyaena (literally, "thick hyena") was a Paleocene genus of heavily built, relatively short-legged mesonychids. The genus may be paraphyletic or monophyletic. Mesonychids were part of a now extinct order of mammals known as Mesonychia, an early group that evolved before modern ungulates or carnivorans, had some similar features to both, and may have been the first large mammals to regularly eat meat.
The genus first appeared in East Asia during the Gashatan ALMA (Asian Land Mammal Age) of the Late Paleocene. Pachyaena would disperse into North America via the Bering land bridge. From North America, it would disperse into Northwestern Europe via the North Atlantic land bridge. However, its presence in Europe was notably short, lasting only 500,000 years. The genus disappears from the fossil record following a faunal turnover event, and was later replaced by Hyaenodictis. In North America, Pachyaena would go extinct around 52.8 Ma. The last population of Pachyaena so far discovered is in the Lushi Formation, which dates to the Irdinmanhan faunal stage (47.8–42.7 Ma).
Text in “About” is quoted from the Wikipedia article Pachyaena (revision 1380945043), 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: Q254141.
