Stratigraphic chart of the lower Permian (partial)
Content updated October 16, 2005
DIMETRODON
Synapsida-Eupelycosauria-Sphenacodontidae
Above: pictures of a sphenacodontid partial braincase (probably of a Dimetrodon) in ventral and lateral views . From Ryan Sandstone, Wellington Formation, near Waurika, Jefferson Co. Oklahoma.
Abbreviations: bpt, basipterygoid process; bsp, fused basisphenoid-parasphenoid; cf, carotid foramen; , ds, dorsum sellae; p, pituitary fossa; pp, parasphenoid pocket; v, venous notch; VII, foramen for palatine branch of facial nerve