Desmostylus hesperus
Desmostylus hesperus.jpg
Name Desmostylus hesperus
Order Desmostylia
Family Hippopotamidae
Class Mammalia
Name Translation Chain Pillar
Period Oligocene-Miocene epochs of the Cenozoic Era
Location North America, Japan (Asia)
Diet Herbivore
Length 1.8 metres (6 feet) long

Desmostylus is a monotypic extinct genus of herbivorous mammal of the family Desmostylidae living from the Chattian stage of the Late Oligocene subepoch through the Late Miocene subepoch (28.4 mya—7.250 mya) and in existence for approximately 21.2 million years.


Desmostylus was a large, a hippopotamus-ofabout 1.8 metres (6 ft) long which weighed about 200 kilograms (440 lb). It had a short tail and powerful legs with four hooves. Both the creature's jaws were elongated and sported forward-facing tusks, which were elongated canines and incisors.

Most likely amphibious, Desmostylus is thought to have lived in shallow water in coastal regions. Some paleontologists have argued it may have fed on seaweed during low tide. However, recent isotope work indicates that Demostylus more likely lived in freshwater or estuary ecosystems and ate aquatic freshwater plants.


D. hesperus (syn. D. japonicus, D. watasei, D. cymatias, D. californicus, D. mirabilis, D. minor, Desmostylella typica)

Sister Genera and Fossil Distribution

Behemotops, Cornwallius, Kronokotherium, Paleoparadoxia

Fossils have been discovered from along the northern Pacific Rim from Baja, Mexico northward along the coast of California, Oregon, Washington and west to Sakhalin Island, Hokkaido, Japan, and south to the Shimane Prefecture, Japan.


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