Hypacrosaurus

Hypacrosaurus altispinus

Hypacrosaurus (meaning "near the highest lizard" [from Ancient Greek ὑπο- hypo- "less" and ἄκρος akros "high"], because it was almost but not quite as large as Tyrannosaurus) is an extinct genus of duckbill dinosaur similar in appearance to Corythosaurus. Like Corythosaurus, it had a tall, hollow rounded crest, although not as large and straight. It is known from the remains of two species that spanned 75.0 to 69.5 million years ago, in the Late Cretaceous of Alberta, Canada, and Montana, United States, and is the latest hollow-crested duckbill known from good remains in North America. It was an obscure genus until the discovery in the 1990s of nests, eggs, and hatchlings belonging to H