any of a family (Hadrosauridae) of large, duck-billed ornithopod dinosaurs of the Cretaceous Period
See hadrosaur in American Heritage Dictionary 4
(hădˈrə-sôrˌ)
noun
Any of various amphibious dinosaurs of the genus Anatosaurus and related genera that had webbed feet and a ducklike bill. Also called duckbill, duck-billed dinosaur.