(Near The Tallest Lizard)
Hy-pa-cro-saur-us. More than 45 different types of duck-billed dinosaurs roamed the Earth during the Jurassic and Late Cretaceous Periods of the Mesozoic Era. Like Corythosaurus, it had a tall, hollow rounded crest above its head. It was an obscure type of duckbilled dinosaur until the discovery in the 1990s of nests, eggs, and hatchlings. Found with fossilized regurgitations from the mothers, these duckbill dinosaurs, once hatched, would not leave the nest until they were capable of finding and chewing their own vegetation. Hypacrosaurus is distinguished from other hollow-crested duckbills (lambeosaurines) by its tall neural spines and the form of its crest. The neural spines, which project from the top of the vertebrae, give it a tall back in profile and acts as protection from predators. The skull’s hollow crest is like that of Corythosaurus and used for communication and thermal regulation.