Parasaurolophus

Parasaurolophus Temporal range: Late Cretaceous (Campanian), 76.9–73.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ Possible record during the Maastrichtian
P. cyrtocristatus skeletal mount at the Field Museum of Natural History.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	†Ornithischia
Clade:	†Neornithischia
Clade:	†Ornithopoda
Family:	†Hadrosauridae
Subfamily:	†Lambeosaurinae
Tribe:	†Parasaurolophini
Genus:	†Parasaurolophus Parks, 1922
Type species
†Parasaurolophus walkeri Parks, 1922
Other species
†P. tubicen Wiman, 1931 †P. cyrtocristatus Ostrom, 1961 †P. jiayinensis? (Godefroit, Zan & Jin, 2000) Paul, 2010
Synonyms[1]
Charonosaurus? Godefroit, Zan & Jin, 2000 Paralophosaurus Martin, 2014 (lapsus calami)

Parasaurolophus (/ˌpærəsɔːˈrɒləfəs, -ˌsɔːrəˈloʊfəs/; meaning "beside crested lizard" in reference to Saurolophus)^[2] is a genus of hadrosaurid "duck-billed" dinosaur that lived in what is now western North America and possibly Asia during the Late Cretaceous period, about 76.5–73 million years ago.^[3] It was a large herbivore that could reach over 9 metres (30 ft) long and weigh over 5 metric tons (5.5 short tons), and were able to move as a biped and a quadruped. Three species are universally recognized: P. walkeri (the type species), P. tubicen, and the short-crested P. cyrtocristatus. Additionally, a fourth species, P. jiayinensis, has been proposed, although it is more commonly placed in the separate genus Charonosaurus. Remains are known from Alberta, New Mexico, and Utah, as well as possibly Heilongjiang if Charonosaurus is in fact part of the genus. The genus was first described in 1922 by William Parks from a skull and partial skeleton found in Alberta.

Parasaurolophus was a hadrosaurid, part of a diverse family of large Late Cretaceous ornithopods that are known for their range of bizarre head adornments, which were likely used for communication and increased hearing. This genus is known for its large, elaborate cranial crest, which forms a long curved tube projecting upwards and back from the skull in its largest form. Charonosaurus from China, which may have been its closest relative, had a similar skull and a potentially similar crest. Visual recognition of both species and sex, acoustic resonance, and thermoregulation have been proposed as functional explanations for the crest. It is one of the rarer hadrosaurids, known from only a handful of good specimens.