Description

Desmostylus hesperus

Middle Miocene

Temblor Formation

Coalinga, CA USA.

44mm molar.

Mammal.  Desmostylia.

Desmostylus is a genus of extinct mammal that lived during the Middle to Late Miocene.  It’s known from sites in California, Oregon, and Japan.

Desmostylus has no modern relatives but its skeleton suggests a hippo-like herbivore in form and behavior. It has been considered a shoreline grazer since its remains are found in marine deposits but an analysis of its tooth enamel concluded that it fed on freshwater plants so it might have frequented estuaries.  Its distinctive, multi-cusped teeth are also unlike those of any mammal today.