The Sphenacodontidae are a family of small to large, advanced, carnivorous, Late Pennsylvanian to middle Permian pelycosaurs. Primitive forms (Haptodus, etc) were generally small in size (60 cm to 1 meter), but during the later part of the early Permian these animals grew progressively larger (up to 3 meters or more), to become the top predators of their environments. The skull's long, deep and narrow, an adaptation for strong jaw muscles. The front teeth are large and dagger-like, whereas the… (More on Sphenacodontidae)