Parasaurolophus was a long-crested, duck-billed dinosaur. Its extremely long, backward leaning, hollow, bony crest was as bigger than the rest of its skull and may have been used to produce a very loud sound. 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. Parasaurolophus grew to be about 22 ft (7 m) long and 8 feet (2.8 m) tall at the hips. It weighed about 2 tons. It had 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 hands were used for swimming. Its sight and hearing were keen, but it had no natural defenses. It had a toothless, horny beak and numerous cheek teeth. Parasaurolophus lived during the late Cretaceous period, about 76-65 Million years ago, toward the end of the Mesozoic era. Its main predators were the Albertosaurus, the relatives of the Tyrannosaurus rex. It was mainly Bipedal but sometimes also walked on all fours.