Edaphosauridae

The Edaphosauridae are a family of mostly large (up to 3 meters or more) advanced, Late Pennsylvanian to Early Permian pelycosaurs.

They were the earliest known herbivorous amniotes, and along with the Diadectidae the earliest known herbivorous tetrapods. The head is small in relation to the bulky body, and there is a tall sail along the back, which may have functioned as a thermoregulatory device. The advanced genus Edaphosaurus was unique in that its "sail" possessed short bony cross bars.

Edaphosaur fossils are so far known only from North America and Europe.