Ornithopod
They reached their apex in the duck-bills, before they were wiped out by the Cretaceous–Tertiary extinction event with all other non-avian dinosaurs. Members are known from all seven continents, although the Antarctic remains are unnamed, and they are generally rare in the Southern Hemisphere. They are the sister group to the horned dinosaurs (Ceratopsia) and the hard-headed dinosaurs (Pachycephalosauria).