Corythosaurus (/kəˌrɪθəˈsɔːrəs/; lit. 'helmeted lizard') is a genus of hadrosaurid "duck-billed" dinosaur from the Upper Cretaceous Period, about 77–75.7 million years ago. It lived in what is now North America. Its name means "helmet lizard", derived from Greek κόρυς. It was named and described in 1914 by Barnum Brown. Corythosaurus is now thought to be a lambeosaurine, related to Nipponosaurus, Velafrons, Hypacrosaurus, and Olorotitan. Corythosaurus has an estimated length of 7.7–9 metres (25–30 ft), and has a skull, including the crest, that is 70.8 centimetres (27.9 in; 2.32 ft) tall.