Hypacrosaurus ("very-high-lizard") is a hadrosaur similar in look to Corythosaurus. Like Corythosaurus, it has a domed crest, although at the time it was named its skull was unknown. This crest differs from that of Corythosaurus in that it is narrower, lower, and less curved in shape. A large hadosaur, it proceedings approx. 9 meters in length. It is recognized from the Early Maastrichtian (late Cretaceous) of Canada and Montana.

The new species Hypacrosaurus stebingeri was named for a variety of hatchlings with associated eggs and nests establish in the Two Medicine Formation in Glacier Creek, Montana. These stand for the largest collection of baby skeletal material of any single species of hadrosaur known.