Saurolophinae is a subfamily of hadrosaurid dinosaurs. It has since the mid-20th century generally been called the Hadrosaurinae, a group of largely non-crested hadrosaurs related to the crested sub-family Lambeosaurinae. However, the name Hadrosaurinae is based on the genus Hadrosaurus which was found in more recent studies to be more primitive than either lambeosaurines or other traditional "hadrosaurines", like Edmontosaurus and Saurolophus. As a result of this, the name Hadrosaurinae was dropped or restricted to Hadrosaurus alone, and the subfamily comprising the traditional "hadrosaurines" was renamed the Saurolophinae. Recent phylogenetic work by Hai Xing indicates that Hadrosaurus is placed within the monophyletic group containing all non-lambeosaurine hadrosaurids. Under this view, the traditional Hadrosaurinae is resurrected, with the Hadrosauridae being divided into two clades: Hadrosaurinae and Lambeosaurinae.
Saurolophinae was first defined as a clade in a 2010 phylogenetic analysis by Prieto-Márquez. Traditionally, the "crestless" branch of the family Hadrosauridae had been named Hadrosaurinae. However, the use of the term Hadrosaurinae was questioned in a comprehensive study of hadrosaurid relationships by Albert Prieto-Márquez in 2010. Prieto-Márquez noted that, though the name Hadrosaurinae had been used for the clade of mostly crestless hadrosaurids by nearly all previous studies, its type species, Hadrosaurus foulkii, has almost always been excluded from the clade that bears its name, in violation of the rules for naming animals set out by the ICZN. Prieto-Márquez (2010) defined Hadrosaurinae as only the lineage containing H. foulkii, and used the name Saurolophinae instead for the traditional grouping.
The following cladogram was recovered in the 2013 phylogenetic analysis by Prieto-Márquez (the relationships within Lambeosaurinae and between basal hadrosauroids aren't shown).
|Fossil mount of Edmontosaurus|
|Genera and tribes|
Acristavus is a genus of saurolophine dinosaur. Fossils have been found from the Campanian Two Medicine Formation in Montana and Wahweap Formation in Utah, United States. The type species A. gagslarsoni was named in 2011. Unlike nearly all hadrosaurids except Edmontosaurus, Acristavus lacked ornamentation on its skull. The discovery of Acristavus is paleontologically significant because it supports the position that the ancestor of all hadrosaurids did not possess cranial ornamentation, and that ornamentation was an adaptation that later arose interdependently in the subfamilies Saurolophinae and Lambeosaurinae. It is closely related to Brachylophosaurus and Maiasaura, and was assigned to a new clade called Brachylophosaurini.Barsboldia
Barsboldia (meaning "of Barsbold", a well-known Mongolian paleontologist) was a genus of large hadrosaurid dinosaur from the early Maastrichtian Nemegt Formation of Ömnogöv', Mongolia. It is known from a partial vertebral column, partial pelvis, and some ribs.Bonapartesaurus
Bonapartesaurus is an extinct genus of herbivorous ornithopod dinosaur belonging to Hadrosauridae, which lived in the area of the modern Argentina during the Campanian and Maastrichtian stages of the Late Cretaceous.Brachylophosaurini
Brachylophosaurini is a tribe of saurolophine hadrosaurs with known material being from N. America and potentially Asia. It contains at least four taxa; Acristavus (from Montana and Utah), Brachylophosaurus (from Montana and Alberta), Maiasaura (also from Montana), and Probrachylophosaurus (also from Montana). A hadrosaur from the Amur river, Wulagasaurus, might be a member of this tribe, but this is disputed. The group was defined by Terry A. Gates and colleagues in 2011.The clade Brachylophosaurini was defined as "Hadrosaurine ornithopods more closely related to Brachylophosaurus, Maiasaura, or Acristavus than to Gryposaurus or Saurolophus".Edmontosaurini
Edmontosaurini are a tribe of saurolophine hadrosaurs that lived in the Northern Hemisphere during the Late Cretaceous period. It currently contains Edmontosaurus (from the United States and Canada), Ugrunaaluk (from Alaska, U.S.), and Shantungosaurus (from Shandong, China), though Anatosaurus might be a distinct genus. Kerberosaurus and Kundurosaurus from Russia could also be members though are more likely saurolophins.Eotrachodon
Eotrachodon orientalis is a species of hadrosaurid that was described in 2016. The holotype was found in the Mooreville Chalk Formation (Upper Santonian) in Alabama in 2007 and includes a well-preserved skull and partial skeleton, making it a rare find among dinosaurs of Appalachia. Another primitive hadrosaur, Lophorhothon, is also known from the same formation, although Eotrachodon lived a few million years prior. A phylogenetic study has found Eotrachodon to be the sister taxon to the hadrosaurid subfamilies Lambeosaurinae and Saurolophinae. This, along with the other Appalachian hadrosaur Hadrosaurus and possibly Lophorhothon, Claosaurus and both species of Hypsibema, suggests that Appalachia was the ancestral area of Hadrosauridae.Hadrosauridae
Hadrosaurids (Greek: ἁδρός, hadrós, "stout, thick"), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The family, which includes ornithopods such as Edmontosaurus and Parasaurolophus, was a common group of herbivores during the Late Cretaceous Period in what is now Asia, Europe, Antarctica, South America, and North America. Hadrosaurids are descendants of the Upper Jurassic/Lower Cretaceous iguanodontian dinosaurs and had a similar body layout.
Like other ornithischians, hadrosaurids had a predentary bone and a pubic bone which was positioned backwards in the pelvis. Hadrosauridae is divided into two principal subfamilies: the lambeosaurines (Lambeosaurinae), which had hollow cranial crests or tubes; and the saurolophines (Saurolophinae), identified as hadrosaurines (Hadrosaurinae) in most pre-2010 works, which lacked hollow cranial crests (solid crests were present in some forms). Saurolophines tended to be bulkier than lambeosaurines. Lambeosaurines included the aralosaurins, tsintaosaurins, lambeosaurins and parasaurolophins, while saurolophines included the brachylophosaurins, kritosaurins, saurolophins and edmontosaurins.
Hadrosaurids were facultative bipeds, with the young of some species walking mostly on two legs and the adults walking mostly on four. Their jaws were evolved for grinding plants, with multiple rows of teeth replacing each other as the teeth wore down.Kerberosaurus
Kerberosaurus (meaning "Kerberos lizard") was a genus of saurolophine duckbill dinosaur from the late Maastrichtian-age Upper Cretaceous Tsagayan Formation of Blagoveshchensk, Amur Region, Russia (dated to 66 million years ago). It is based on bonebed material including skull remains indicating that it was related to Saurolophus and Prosaurolophus.Kritosaurini
Kritosaurini is a clade of saurolophine hadrosaurid dinosaurs from the Late Cretaceous.Laiyangosaurus
Laiyangosaurus ("Laiyang lizard") is a genus of saurolophine hadrosaurid from the Late Cretaceous of China. It is known from one species, L.youngi, found in the Laiyang Basin within the province of Shandong.Probrachylophosaurus
Probrachylophosaurus bergei is a species of large herbivorous brachylophosaurin hadrosaurid dinosaur known from the Late Cretaceous Campanian Judith River Formation, of Montana.
The significance of this particular hadrosaur taxon is that it is a transitional species between the genera Acristavus and Brachylophosaurus evolving from a crestless ancestor (the former genus) to its crested descendant (the latter genus) while changing the morphology of its nasal bones.Prosaurolophus
Prosaurolophus (; meaning "before Saurolophus", in comparison to the later dinosaur with a similar head crest) is a genus of hadrosaurid (or duck-billed) 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 (30 ft), 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.Rhinorex
Rhinorex is a genus of kritosaurin hadrosaur from the Late Cretaceous Neslen Formation, in central Utah. Its exact placement in time is uncertain, though it probably dates to 75 million years ago and was discovered in estuarine sediments.It is likely a close relative of Gryposaurus, and indeed some have suggested that it falls within the genus Gryposaurus, as the phylogenetic analysis indicates.It is found in a very similar time and place as Gryposaurus monumentensis and Gryposaurus sp. This would challenge the idea of provincialism in Late Cretaceous Laramidian faunas. It may be that Rhinorex lived in more coastal environments than Gryposaurus. The holotype specimen BYU 13258 is composed of a partial but mostly articulated skeleton, which includes the skull, the vertebral column and a partial pelvis.Saurolophini
Saurolophini is a tribe of saurolophine hadrosaurid native to the Americas and Asia. It includes Saurolophus (from Canada and Mongolia), Augustynolophus (from the United States), and Prosaurolophus (from Alberta, Canada, and Montana, U.S.). Kerberosaurus and Kundurosaurus may also be members. Bonapartesaurus, a hadrosaurid from Argentina, also has been identified as a member of this tribe.Fossils of saurolophins have been found in Canada, the United States and Asia, with the North American fossils being older than the Asian, suggesting saurolophins migrated intra-continentally.Saurolophus
Saurolophus (; meaning "lizard crest") is a genus of large saurolophine hadrosaurid dinosaurs that lived about 70.0–66 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. Saurolophus was a 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.Secernosaurus
Secernosaurus (meaning "severed lizard") is a genus of herbivorous dinosaur. Secernosaurus was a hadrosaur, a "duck-billed" dinosaur which lived during the Late Cretaceous. Its fossils have been found in the Lago Colhué Huapi and Los Alamitos Formations of Argentina.Shantungosaurus
Shantungosaurus, meaning "Shandong Lizard", is a genus of saurolophine hadrosaurid dinosaurs found in the Late Cretaceous Wangshi Group of the Shandong Peninsula in China. The stratigraphic interval of Shantungosaurus ranges from the top of the Xingezhuang Formation to the middle of the Hongtuya Formation, middle to late Campanian in age. Shantungosaurus is so far the largest hadrosauroid taxon in the world: the greatest length of its femur is about 1.7 m, and the greatest length of its humerus is about 0.97 m.Ugrunaaluk
Ugrunaaluk is a dubious genus of saurolophine hadrosaurid which was found in the Arctic of Alaska. It contains the species Ugrunaaluk kuukpikensis. Its name is derived from the Inupiat words for 'ancient grazer'.
From the 1980s onwards, in Alaska more than six thousand bones of hadrosaurid dinosaurs have been uncovered, at the Colville River. They were found north of Umiat in the Liscomb bonebed. At first they were identified as belonging to some member of the Lambeosaurinae. Later, they were referred to Edmontosaurus, more specifically Edmontosaurus regalis, a member of the Saurolophinae. A definite identification was hampered by the fact that most of the bones were of juveniles. In 2014, Hirotsugu Mori solved this problem by statistically determining size classes within the fossil material and comparing the Alaskan bones with known Edmontosaurus annectens specimens of the same size. He concluded that they represented two separate species.The discovery of the new genus was published online on 22 September 2015 by Hirotsugu Mori, Patrick Druckenmiller and Gregory Erickson. Ugrunaaluk was one of eighteen dinosaur taxa from 2015 to be described in open access or free-to-read journals. However, the identification of Ugrunaaluk as a separate genus was questioned by a 2017 study from Hai Xing and colleagues, who regarded it as a nomen dubium indistinguishable from other Edmontosaurus.Willinakaqe
Willinakaqe is a possibly invalid genus of saurolophine hadrosaurid dinosaur described based on fossils the late Cretaceous (late Campanian-early Maastrichtian stage) of the Río Negro Province of southern Argentina.