**Hadrosaur: The Duck-Billed Dinosaur of the Cretaceous Era**
Hadrosaurs are known as the duck-billed dinosaurs of the Cretaceous period. They lived from 75 to 65 million years ago. The family Hadrosauridae is divided into two categories: those with hollow cranial crests that may have used to blast auditory signals, and those without. Hadrosaurs were fast running herbivores that dwelled on land and had evolved a unique way of chewing their food.
Hadrosaur anatomy has been frequently well-preserved. Hadrosaurs are found in North America, Europe, and Asia. They are Ornithchians (meaning bird-hipped), and have Iguanodont ancestors that emerged in the Middle Jurassic era.