- An order of herbivorous dinosaurs with birdlike attributes into the skeleton, esp. in pelvis and hind feet, which in some genera had just three useful toes, and supported the body in walking as in Iguanodon. See Illust. in Appendix.
- An order of Dinosauria, containing extinct herbivorous dinosaurs whose hind foot many nearly approached those of wild birds in framework and purpose.
- extensive team including duck-billed dinosaurs and their early family members (hadrosaurs, trachodon and iguanodon)