Coryphodon, a hoofed herbivore with large canine teeth, Paleocene and Eocene

Coryphodon was a hoofed herbivore that lived during the Paleocene to toward the end of the Eocene (approximately 60 to 35 m.y. ago). In the Paleocene, they lived only in Asia. In the Eocene, they only lived in North America.

They belong to the pantodont ambylpods (amblypod = “slow footed”) that had a long (2.25 m = 7.4 ft.), heavy body (1,100 lbs.) with a large head, massive neck muscles, and canine tusks used for uprooting swamp plants.  Pantodonts were among the first great wave of diversification of placental herbivores. Coryphodon was the biggest known mammal of its time. It was probably a slow and clumsy animal. It ate leavers, young shoots, and flowers. It had one of the smallest brain/body ratios of any mammal, living or extinct. Its brain weighed only 3.2 oz.

Coryphodon (original sketch and painting by R. Squires, May, 2015).

Three canine teeth of Coryphodon. The smallest tooth is 4.5 cm length and 2.5 cm width.
The largest tooth is 7.2 cm length and 2 cm width.

Its semi-aquatic lifestyle of living in marshes and swamps was likely similar to that of a hippopotamus although Coryphodon was not closely related to modern hippos or any other animal known today. Fossils found on Ellesmere Island, near Greenland, indicate that Coryphodon once lived there in warm swampy forests of huge trees, much like the modern cypress swamps of southern Florida.