Corythosaurus is a genus of hadrosaurid dinosaur in the subfamily Lambeosaurinae. It originally lived during the Campanian age of the Cretaceous period, between 77 and 75.7 million years ago. Corythosaurus fossils have been found in western North America. The type species is Corythosaurus casuarius. There is also a second species, Corythosaurus intermedius, which lived slightly more recently in time and had a smaller crest.