Corythosaurus are hadrosaurs ('duck-billed dinosaurs') once living in North America. They are herbivores that lived in herds. They were one of the larger types of hadrosaurs. Their heads had crests, with nasal passages, and are similar in structure to that of the cassowary. This was most likely used for vocalisation. Their name means 'Corinthian-crested Lizard' in reference to this crest. The crests also show dimorphism between the genders, with males believed to have the larger crests for competing with mates.