Parasaurolophus is a genus of dinosaur that lived in what is now North America during the Late Cretaceous Period, about 75 million years ago. A member of the Hadrosaurid or duck-billed dinosaurs, it was a plant-eater that walked on two legs or all four. Three species are recognized: P. walkeri, P. tubicen, and the short-crested P. cyrtocristatus. Remains are known from Alberta, New Mexico, and Utah. It is known for its large, elaborate cranial crest, which forms a long curved tube projecting upwards and back from the skull. The crest's purpose has been debated by scientists; possible functions include thermoregulation, visual recognition of both species and sex, and trumpeting. The genus was first described in 1922 by William Parks from a skull and partial skeleton in Alberta. Only a handful of good specimens are known. (more...)
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