Saurolophus (pron.: /sɔːˈrɒləfəs/; meaning "lizard crest") is a genus of large hadrosaurine duckbill that lived about 69.5-68.5 million years ago, in the Late Cretaceous of North America and Asia; it is one of the few genera of dinosaurs known from multiple continents. It is distinguished by a spike-like crest which projects up and back from the skull. At 40 feet (12 metres), Saurolophus was one of the larger of the hadrosaur family. Saurolophus was an herbivorous dinosaur which could move about either bipedally or quadrupedally. The type species, S. osborni, was described by Barnum Brown in 1912 from Canadian fossils. A second valid species, S. angustirostris, is represented by numerous specimens from Mongolia, and was described by Anatoly Konstantinovich Rozhdestvensky. A third species, S. "morrisi" from California, was a nomen nudum as of 2011, and a fourth species, S. kryschtofovici from China, is considered dubious.