Secodontosaurus willistoni
Early Permian
Arroyo formation
Haskell county
Texas, USA.

Secodontosaurus was a carnivorous member of the sphenacodontid group, closely related to the better known Dimetrodon. Its specialized teeth were adapted for capturing prey, reflecting the development of advanced predatory features among early synapsids.
Excellent 10mm pelycosaur tooth.