Edaphosaurus
The roof of the mouth and the inside of the lower jaw had batteries of peglike teeth. They were a crushing and grinding surface. Early descriptions suggested that Edaphosaurus fed on molluscs, which it crushed with its teeth plates. However, paleontologists now think that Edaphosaurus ate plants. Lack of wear on the teeth suggests "limited processing of food". Earlier members of the Edaphosauridae  lacked tooth plates, and ate insects.