 In more derived forms like "Lycorhinus" and "Heterodontosaurus", the teeth were chisel-shaped, with much higher crowns and no cingula, so that there was no difference in width between the crowns and the roots.These derived cheek teeth were overlapping, so that their crowns formed a continuous surface on which food could be chewed.The tooth rows were slightly inset from the side of the mouth, leaving a space outside the teeth that may have been bounded by a muscular cheek, which would have been necessary for chewing.