Altacreodus fossil map
Where fossils of Altacreodus have been found, shown on the Earth as it looked about 66 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 66 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 | 72.2–66 million years ago (Maastrichtian) |
| Periods | Cretaceous |
| Named by | Fox 2015 |
| Fossil records | 20 occurrences at 8 locations (PBDB) |
| Found in | United States, Canada |
| Rock formations | Scollard, Hell Creek, Lance, Frenchman |
About Altacreodus
Altacreodus ("creodont from Alberta") is an extinct genus of eutherian mammals. Fossils have been found in North America where they first appeared during the Late Cretaceous, and they died out prior to the start of the Paleocene. It is possibly one of the earliest known placental mammals in the fossil record.
The type species is "Cimolestes" magnus, which was renamed Altacreodus magnus in 2015. Based on the dimensions of its preserved remains, its size was comparable to the large metatherian Didelphodon. Recent phylogenetic analyses suggests that genus Altacreodus is a member of clade Pan-Carnivora and the closest known sister taxon to order Hyaenodonta, based on anatomy of its teeth. In some studies its position as a crown-group placental has been equivocal.
Text in “About” is quoted from the Wikipedia article Altacreodus (revision 1313946145), 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: Q55603737.
