|
LIST OF THE RICHARDS SPUR (FORT SILL) TETRAPOD PALEOFAUNA Stratigraphic chart of the lower Permian (partial) Content updated April 10, 2006
|
DIMETRODON Synapsida-Eupelycosauria-Sphenacodontidae
Dimetrodon is a medium to large size synapsid eupelycosaur sphenacodontid and one of the most common tetrapod of the lower Permian of North America. It is characterized by reduction of quadratojugal, a well developed retroarticular process and a reflected lamina of angular, these characters are shared with therapsids and make sphenacodontids the sister group of therapsid and the mammals. The teeth are square in cross section near the base with anterior and posterior serrated cutting ridges. the vertebrae have sharp keeled centra with deep excavated neural arches at the base of the long neural spines, the zygapophyses are tilted and not extend, laterally, beyond the margin of the centra. 1) Dimetrodon: maxilla fragment 2) Dimetrodon: partial braincase 3) Dimetrodon: basioccipital/exoccipital 4) Dimetrodon: cervical vertebra 5) Dimetrodon: base of neural spine (lateral) 6) Dimetrodon: base of neural spine (frontal) 7) Dimetrodon: neural spine fragment (lateral) 8) Dimetrodon: neural spine fragment (frontal) |