Hypacrosaurus

Hypacrosaurus (meaning "almost the largest lizard") was a large, plant-eating, hollow-crested duck-billed dinosaur similar to Corythosaurus. 

The adults were about 30 feet (9 m) long. Their teeth were continually replacing, and packed into dental batteries that contained hundreds of teeth. Only a relative handful of teeth were in use at any one time. They had a short toothless beak. 

A row of long spines from their vertebrae formed a high fin along the back. The fossils are dated as 75 to 67 million years ago. 

Remains have been found of two species in the Upper Cretaceous of Alberta, Canada, and Montana, United States. It is the latest hollow-crested duckbill known from good remains in North America. In the 1990s nests, eggs, and hatchlings of one of the species was found.

 References 

category:Hadrosauridae