Lambdotherium fossil map
Where fossils of Lambdotherium 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 | 56–45.9 million years ago (Ypresian to Lutetian) |
| Periods | Paleogene |
| Family | Brontotheriidae |
| Named by | Cope 1880 |
| Fossil records | 162 occurrences at 19 locations (PBDB) |
| Found in | United States, Canada |
| Rock formations | Wind River, Wasatch, DeBeque, Willwood, Green River, Huerfano |
About Lambdotherium
Lambdotherium ("lambda beast") is a genus of North American perissodactyl from the lower Eocene. The genus is currently monospecific, containing only the species L. popoagicum. Lambdotherium is traditionally interpreted as a close relative of the brontotheres; some studies propose alternate placements, such as Lambdotherium being a primitive palaeothere or a close relative of that group.
Text in “About” is quoted from the Wikipedia article Lambdotherium (revision 1368824409), 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: Q937158.
