Prehistoric Life Prehistoric Secrets in Stone The Earliest Fossils The Silurian Reef Trilobites Fish The Coal Forests Early Reptiles and Amphibians Sea Reptiles Flying Reptiles The Teeming Seas Hunting Dinosaurs Biggest Dinosaurs Two-Footed Plant Eaters Plated and Armoured Dinosaurs Horned Dinosaurs The Mammal Age Dawns Grassland Mammals The Ice Age	Corythosaurus This was a large duckbill with a hollow crest like an ancient Greek helmet. The tubes in the crest could have helped it to make loud calls.   Previous: Back Book: Prehistoric Life Section: Prehistoric Chapter: Two-Footed Plant Eaters