Edaphosaurus

Edaphosaurus was a primitive, herbivorous pelycosaur. Along with the Diadectidae, Edaphosaurus is one of the earliest known plant-eating tetrapods (land-living vertebrates). It had a remarkably small, short and shallow skull, a wide body and thick tail. On its back is a sail, different in shape to that of its contemporary Dimetrodon, the vertebral spines being shorter and heavier and bearing numerous small cross bars.

The earliest known species are known from fragmentary remains of small animals from late Carboniferous. Successive species increased in size during the Early Permian period, until they attained about 3.2 meters in length, as represented by the species Edaphosaurus cruciger and Edaphosaurus pogonias. These large species are distinguished by the cervical and anterior thoracic neural spines bearing large club-like sidebars.

Edaphosaurus pogonias is also the type species, a large Early Permian form whose fossils are known from the Permian red beds of Texas. This genus is also known from the Czech Republic (Nýřany near Plzeň, and Zbýšov near Brno). However it is not known for certain if all these species attributed to this genus actually belong there. The name Naosaurus claviger is given to an earlier smaller species that is usually included under Edaphosaurus.