page_title: Prosaurolophus
section_title: Phylogeny
hierarchical_section_title: Prosaurolophus / Classification / Phylogeny
caption_attribution_description: English: Royal Tyrrell Museum Prosaurolophus
context_page_description: Prosaurolophus is a genus of hadrosaurid dinosaur from the Late Cretaceous of North America. It is known from the remains of at least 25 individuals belonging to two species, including skulls and skeletons, but it remains obscure. Around 9 m, its fossils have been found in the late Campanian-age Upper Cretaceous Dinosaur Park Formation in Alberta, and the roughly contemporaneous Two Medicine Formation in Montana, dating to around 75.5-74.0 million years ago. Its most recognizable feature is a small solid crest formed by the nasal bones, sticking up in front of the eyes.
  The type species is P. maximus, described by American paleontologist Barnum Brown of the American Museum of Natural History in 1916. A second species, P. blackfeetensis, was described by Jack Horner of the Museum of the Rockies in 1992. The two species were differentiated mainly by crest size and skull proportions.
context_section_description: The first cladistic analysis to encompass the interrelationships of Hadrosauridae was conducted by Weishampel and Horner (1990). They found Saurolophinae synonymous with Hadrosaurinae, but only separated the subfamily into two groups. The first group included Gryposaurus, Aralosaurus, Maiasaura, and Brachylophosaurus. The other contained Edmontosaurus, Saurolophus, Prosaurolophus, Lophorhothon, and Shantungosaurus.
  A detailed cladgram of hadrosaurid relationships was published in 2013 by Acta Palaeontologica Polonica. The study was led by Alberto Prieto-Márquez, and recovered Prosaurolophus in a similar position as suggested by Brown in 1916. The below cladogram was the one recovered by their analysis:
   
  In 2001, Prosaurolophus was studied with other hadrosaurids by Wagner. The genus, along with Corythosaurus and Maiasaura, were considered by Wagner to be synonymous with Saurolophus, Hypacrosaurus and Brachylophosaurus respectively. Prosaurolophus maximus was reassigned to Saurolophus as S. maximus. The same year however, Prosaurolophus was found to be distinct from Saurolophus, in an analysis of Hu et al.. Their analysis was unique from any of the time, and they recovered Prosaurolophus in Saurolophinae, with Saurolophus, Lophorhothon, Tsintaosaurus, Jaxartosaurus, and Kritosaurus. No other analysis has recovered this group of dinosaurs.
  Horner et al. (2004) also recovered a different phylogeny of Saurolophinae. Prosaurolophus was, for the first time, recovered separate from Saurolophus, in fact not even closely related. Prosaurolophus was found in a group with Brachylophosaurus, Maiasaura, Grpyosaurus, and Edmontosaurus, while Saurolophus was grouped with Naashoibitosaurus (=Kritosaurus) and "Kritosaurus" australis.
  The Prosaurolophus-Saurolophus clade has been a problematic grouping when trying to place among hadrosaurines. Many skull features are similar to Edmontosaurus, while other are closer to Gryposaurus, so the group has been classified as close to both. However, the clade might be closer to Edmontosaurus, as the features are more numerous uniting them.
caption: Skeletal mount, Royal Tyrrell Museum of Paleontology
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