Corythosaurus is a genus of hadrosaurid (i.e. 'duck-billed') dinosaurs, planet eaters, that lived in what is now North America towards the end of the Cretaceous period, roughly 75 million years ago. The name comes from the crest on its head, which suggested to its discoverer the helmet of a Corinthian soldier. Some scientists speculate that the crest acted as a kind of resonance chamber that permitted the animal to emit amplified, low-pitched cries, perhaps to warn others of danger or to point out sources of food.