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Temporal range: Late Eocene–Early Miocene
Metamynodon planifrons skeleton
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Amynodontidae
Genus: Metamynodon
Scott & Osborn, 1887
Type species
Metamynodon planifrons
  • M. planifrons
  • M. chadronensis
  • M. mckinneyi

Metamynodon is an extinct genus of amynodont perissodactyls, and is among the longest lived genera of amynodonts, having first appeared during the late Eocene, and becoming extinct during the early Miocene, when it was supplanted by the semiaquatic rhinoceros, Teleoceras. Its fossils have been discovered in the United States (White River Fauna), Mongolia and China.


Restoration by Charles R. Knight
Restoration by Heinrich Harder

Metamynodon planifrons, the largest species, was about 4 metres (13 ft) in body length with a weight up to 1.99 tons, and, although it was distantly related to the modern rhinoceros, looked more like a hippopotamus.[1] Its front legs had four toes instead of the three found in modern rhinos. Although it was a herbivore (as indicated by its teeth), its skull had a bony ridge typically associated with carnivorous mammals. It probably fed on tough plant material, and the jaw muscles were attached to this ridge. Metamynodon would have used its enlarged canines to search for food in river banks, and may also have had highly flexible lips. Its eyes were placed high on the skull, meaning that it would have been able to see while almost fully submerged, much like a hippopotamus or crocodile.[2]


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  2. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 264. ISBN 1-84028-152-9.