Slaugenhopia was found from the San Angelo Formation within the Kahn Quarry of Driver Ranch in
Knox County, Texas. Although it was known only from fragments, paleontologist
Everett C. Olson reconstructed the entire skull when he named the genus in 1962. He placed the genus in the dvinosaur family Trimerorhachidae and thought that it was intermediate between the dvinosaurs
Trimerorhachis and
Dvinosaurus based on the shape of the skull. A mandible that was found earlier in
Little Croton Creek was also referred to
Slaugenhopia.
Slaugenhopia continued to be classified as a trimerorhachid until 1999 when a new dvinosaur called
Thabanchuia was named from
South Africa.
Thabanchuia is a member of the family Tupilakosauridae and shares many similarities with
Slaugenhopia. Because of these similarities,
Slaugenhopia is now considered a tupilakosaurid. Defining characteristics of
Slaugenhopia include a notch in the pterygoid bone of the
palate called the pterygoid incisure; the wideness of a projection of bone in the palate called the
cultriform process, a wide contact between the
parasphenoid and
basisphenoid bones on the underside of the skull, and uniquely L-shaped
postparietal bones at the back of the skull. Another Early Permian dvinosaur called
Kourerpeton is also known from Texas and may be related to
Slaugenhopia. Both dvinosaurs have an enlarged
postorbital bone and a small
postfrontal bone near the eye sockets. They also have similar vertebrae, with ring-like
intercentra and small, crescent-shaped
pleurocentra. While the posterior margin of the skull is relatively straight in
Slaugenhopia, the same margin is curved and irregular in
Kourerpeton.
Kourerpeton also lacks the pterygoid incisure of
Slaugenhopia, which is characteristic of other tupilakosaurids as well. Based on these differences,
Kourerpeton is probably a basal relative of tupilakosaurids, including
Slaugenhopia. ==References==