Parasaurolophus

Parasaurolophus was a long-crested, duck-billed dinosaur.

Description
Its extremely long, backwards-leaning, hollow, bony crest was as bigger than the rest of its skull and may have been used to produce a low-frequency, foghorn-like sound, enhance its sense of smell, and/or used in courtship displays. The Parasaurolophus' nostrils (at the end of its snout) went up through the crest and back down it, forming four tubes. The crest was up to 6 feet (1.8 m) long. Its snout was narrow and shorter than other hadrosaur snouts. There may have been sex differences in the length of the crest; males may have had longer crests. Parasaurolophus also had a notch in its back, right where the crest would touch the back when its head leaned backwards. Parasaurolophus grew to be about 33 ft (10 m) long and 8 feet (2.8 m) tall at the hips. It weighed about 2 tons. It had pebbly-textured skin, a spoon-shaped beak, and a pointy tail. It may have had webbed fingers, giving it a mitten-like hand, but some paleontologists argue that the web-like fossilized hands are an artifact of the fossilization process. Its sight and hearing were keen, but it had no natural defenses. It had a toothless, horny beak and numerous cheek teeth. Parasaurolophus may have been a herding animal; it may have migrated from shorelines to higher ground to reproduce. There is no evidence that Parasaurolophus spent much time in the water. It used to be thought that its crest was used as a snorkel-like device, indicating that the animal spent much time in the water, but since the crest has no nostril at the top, this theory has been dismissed. Also, fossilized stomach contents have been found, consisting mostly of land plants. Again, this indicates that Parasaurolophus spent most of its time on land.

Parasaurolophus lived during the late Cretaceous period, about 76-65 Million years ago, toward the end of the Mesozoic, the Age of Reptiles. Among the contemporaries of Parasaurolophus in the late-Cretaceous (in North America) were Albertosaurus, Nanotyrannus, Lambeosaurus (another hadrosaur), Euoplocephalus, Kritosaurus, and Pachyrhinosaurus. Parasaurolophus was an herbivore, eating pine needles, leaves, and twigs. Fossilized stomach contents have been found, consisting mostly of land plants. Parasaurolophus was an ornithopod, whose intelligence (as measured by its relative brain to body weight, or EQ) was midway among the dinosaurs. Parasaurolophus walked and ran on two legs, and was a relatively fast dinosaur. It probably went on all fours to forage for plants. It may have spent some time in the water. Parasaurolophus was described and named by Dr. William A. Parks in 1922 from an almost complete skeleton found in Alberta, Canada. Many fossils have been found in North America (in Alberta, Canada and New Mexico and Utah in the USA).