Metamynodon fossil map
Where fossils of Metamynodon 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 | 48.07–31.8 million years ago (Lutetian to Rupelian) |
| Periods | Paleogene |
| Family | Amynodontidae |
| Named by | Scott and Osborn 1887 |
| Fossil records | 46 occurrences at 16 locations (PBDB) |
| Found in | United States, Myanmar, China |
| Rock formations | Pondaung, Brule, Colmena Tuff, Devil's Graveyard, txn:43168, Byram |
About Metamynodon
Metamynodon is an extinct genus of amynodont that lived in North America from the Middle Eocene to the Middle Oligocene. Metamynodon was a large, robust, and semiaquatic animal that displayed a suite of adaptations towards an amphibious lifestyle. Many of these features showcase convergent evolution with the modern hippopotamus, though Metamynodon is most closely related to rhinoceroses.
Fossils of Metamynodon were first discovered in the late 20th century. The type species of Metamynodon, M. planifrons, is known from near-complete fossils and is thus relatively well understood anatomically. Two additional species based on more fragmentary remains are often recognized, M. chadronensis and M. mckinneyi, though their taxonomic validity has been questioned since the 1980s. M. planifrons was the largest species, about the same size as large modern rhinoceroses. The largest M. planifrons measured up to 4.3 metres (14 ft) long and weighed about 1,800 kilograms (4,000 lb). The skull of Metamynodon was broad and flat. Dentally, it was characterized by large and tusk-like canines, and high-crowned cheek teeth. The body was stout and barrel-shaped, and the legs were relatively short.
Text in “About” is quoted from the Wikipedia article Metamynodon (revision 1379475527), 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: Q2145432.
