(pronounced ig-WAHN-oh-DON-tids) Iguanodontids (family Iguanodontidae, also called Iguanodonts) were large, plant-eating, ornithischian ornithopods who lived from the late Jurassic to the late Cretaceous periods. These dinosaurs had a thumb spike, a toothless beak, a long snout, long toes, and a bulky tail. Altirhinus, Iguanodon , Camptosaurus , Ou...