Stratigraphic chart of the lower Permian (partial)
Content updated October 16, 2005
RICHARDS SPUR UNIDENTIFIED
SPHENACODONTID
Synapsida-Eupelycosauria-Sphenacodontidae
Above: pictures of the same dorsal vertebra: anterior and posterior view. From Richards Spur (Dolese Quarry) - Comanche Co. Oklahoma. Lower Permian.