Temporal range: Upper Cretaceous
Like other hadrosaurs, it had a hollow, bony crest on top of its long head in the shape of a helmet flattened on the sides (Corythosaurus means "helmet lizard"). Its likely functions were sound projection and recognition. Males had larger crests than females and juveniles.
Corythosaurus was like other hadrosaurids, and could move on both two legs and all fours, as shown by footprints of related animals. It had a long tail stiffened by bony tendons that stopped it from drooping. The hands had four fingers, lacking the innermost finger of the hand. The second, third, and fourth fingers were bunched together and bore hooves, suggesting the animal could have used the hands for support. The fifth finger was free and could be used to manipulate objects. Each foot had only the three central toes.