Tianyulong (Age of the Dinosaurs by PNSO)4.1 (13)
A lot of ornithischian dinosaurs lacked teeth in the front of the mouth, having only cheek teeth that ground up food, and often a beak for clipping vegetation. The family Heterodontosauridae (“different-toothed lizards”) was unusual among ornithischians in having three different kinds of teeth in different parts of the mouth. Having different teeth to divide the labor of food processing...