Parasaurolophus (name meaning "Near-Crested Lizard") is a genus of herbivorous ornithopod hadrosaur dinosaur that lived in what is now North America during the Late Cretaceous period, about 77–65 MYA. It was related to Iguanodon and Edmontosaurus. It walked both on all four legs and ran on just two. Parasaurolophus had a long crest on its head and grew to 10 meters long - medium-sized by dinosaur standards, so it lived in herds to protect it from predators such as Deinosuchus and Albertosaurus.
Parasaurolophus lived during the Late Cretaceous in North America from 76-65 million years ago, living up until the dinosaurs died out. They shaired their environments with other hadrosaurus, like Edmontosaurus, the ceratopcian dinosaurs, Ankylosaurus, and was also preyed upon by the raptor dinosaurs, Deinosuchus, and the large Tyranosaur family. Parasaurolophus was first described in 1922 by William Parks.
Parasaurolophus were relatively large dinosaurs, with. adults measuring around 30–36 feet (9–11 m) in length and weighing in at 5-6 tons. The cones, or crests, on top of their heads were brightly colored and Parasaurolophus used them for display.
As another member of the hadrosaur family, a common group of dinosaurs at the end of the Late Cretaceous, Parasaurolophus was a herbivore that walked both as a biped and a quadruped. Parasaurolophus spent most of their time on all four legs and ran very fast on just two legs and only ran bipedally to move fast in order to get away from danger. Like their Asian cousin Saurolophus, they had got duck bills for grinding vegetation.
Parasaurolophus is known for its large, elaborate cranial crest, which at its largest forms a long curved tube projecting upwards and back from the skull. The crest has been much discussed by scientists; the consensus is that major functions included visual recognition of both species and sex, acoustic resonance, and thermoregulation. It is one of the rarer hadrosaurids, known from only a handful of good specimens.
Like all hadrosaurs and other herbivorous dinosaurs, Parasaurolophus lived in large herds of dozens, even hundreds of individuals. They were said to use their long crests as to form communication between members of the herd.