Parasaurolophus ('near-crested lizard'), first described in 1922, was a dinosaur that lived at the end of the Cretaceous period, around 70 million years ago, in what is now North America. It was a hadrosaurid dinosaur, a diverse family of plant-eating animals with odd-shaped skulls. Three species are recognised, based mainly on the size of the head crest: P. walkeri (shown in this artwork), P. tubicen and P. cyrtocristatus, with the largest measuring around 9.5 m (31 ft) in length.