Parasaurolophus was one of the largest known duck-billed dinosaurs from North America. The tube-like, bony crest on its head may have produced loud trumpeting sounds. This peaceful plant-eater walked on four legs most of the time but could rear up and run on two legs when it was in a hurry. It occupied Canada during the Cretaceous Period about 75 million years ago. History: The stunning crest of Parasaurolophus has generated much speculation over the years. When Parasaurolophus was first discovered, it was presumed to be amphibious, and so some paleontologists suggested it could use its hollow crest as a snorkel. However, the tip of the crest is completely closed, so this theory has been generally dismissed. Alternatively, it is possible that the hollow crest was used as a resonating chamber to generate loud bellowing sounds. Scientific Name: Parasaurolophus walkeri Characteristics: There is no mistaking Parasaurolophus’ distinctive crest, which is long, tubular.