Stratigraphic chart of the lower Permian (partial)
Content updated October 16, 2005
EDAPHOSAURUS
Synapsida-Eupelycosauria-Edaphosauridae
Above: picture of Edaphosaurus basioccipital in ventral view, showing the presence of the medial ridge that arises from the ventral lip of the condyle and merges anteriorly with the body of the basioccipital. From Ryan Sandstone, Wellington Formation, near Waurika - Jefferson Co. Oklahoma Lower Permian.