With fossils found from the Kasimovian (Missourian) stage of the Late Carboniferous of Pennsylvania, Colorado, and New Mexico in the United States,[1] Desmatodon is the oldest known diadectid.

The cheek teeth are robust and spade-shaped with several cusps on their surfaces.

In both species, the lower jaw is deep and possesses a ridge that may have aided in chewing plant material.

Some specimens that are thought to belong to young individuals have fewer, more widely spaced teeth with no wear facets.

[2] Like most other diadectids, Desmatodon was a terrestrial herbivore that consumed high-fiber plants.