Saurolophinae is a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

hadrosaurid Hadrosaurids (), also hadrosaurs 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 ornithopod fami ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s. It has since the mid-20th century generally been called the

Hadrosaurinae Hadrosaurids (), also hadrosaurs 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 ornithopod fami ...

, a group of largely non-crested hadrosaurs related to the crested sub-family

Lambeosaurinae Lambeosauridae /ˌlæmbiəˈsɔːraɪniː/ (meaning 'lambe's lizards') is an extinct group of crested hadrosauroid dinosaurs. Description Size Uncertainty surrounds the size of lambeosaurs from the European continent. Hadrosaurs found there, ...

. However, the name Hadrosaurinae is based on the genus ''

Hadrosaurus ''Hadrosaurus'' (; ) is a genus of hadrosaurid ornithopod dinosaurs that lived in North America during the Late Cretaceous Period in what is now the Woodbury Formation in New Jersey about 83.6 to 77.9 Ma. The holotype specimen was found in flu ...

'' which was found in more recent studies to be more primitive than either lambeosaurines or other traditional "hadrosaurines", like ''

Edmontosaurus ''Edmontosaurus'' ( ) (meaning "lizard from Edmonton"), with the second species often colloquially and historically known as ''Anatosaurus'' or ''Anatotitan'' (meaning "duck lizard" and "giant duck"), is a genus of hadrosaurid (duck-billed) din ...

'' and ''

Saurolophus ''Saurolophus'' (; meaning "lizard crest") is a genus of large hadrosaurid dinosaur from the Late Cretaceous period of Asia and North America, that lived in what is now the Horseshoe Canyon and Nemegt formations about 70 million to 66 million ...

''. 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 ''

'' is placed within the monophyletic group containing all non-lambeosaurine hadrosaurids. Under this view, the traditional

is resurrected, with the

Hadrosauridae Hadrosaurids (), also hadrosaurs 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 ornithopod fam ...

being divided into two clades:

and

Classification

Saurolophinae was first defined as a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

in a 2010 phylogenetic analysis by Prieto-Márquez. Traditionally, the "crestless" branch of the family

had been named

. 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 The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its formal author, t ...

. Prieto-Márquez (2010) defined Hadrosaurinae as only the lineage containing ''H. foulkii'', and used the name Saurolophinae instead for the traditional grouping. In a 2023 study, Alarcón-Muñoz ''et al.'' implemented an updated version of the phylogenetic matrix of Rozadilla ''et al''. (2022) to analyze the relationships of saurolophines and hadrosaurids. The results of their

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

of Saurolophinae are displayed in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below.

Subgroups

The

Brachylophosaurini was defined by Terry Gates and colleagues in 2011 as "Hadrosaurine ornithopods more closely related to ''Brachylophosaurus'', ''Maiasaura'', or ''Acristavus'' than to ''Gryposaurus'' or ''Saurolophus''". In 2021, Madzia et al. registered Brachylophosaurini in the PhyloCode and formally defined it as "The largest clade containing ''Brachylophosaurus canadensis'' but not ''Edmontosaurus regalis'', ''Hadrosaurus foulkii'', ''Kritosaurus navajovius'' and ''Saurolophus osborni''". The name "Kritosaurini" was first mentioned in 1955 by Lapparent & Lavocat, where they mentioned "‘Kritosaurinés" as a group of hadrosaurids containing only ''

Kritosaurus ''Kritosaurus'' is an incompletely known genus of hadrosaurid (duck-billed) dinosaur. It lived about 74.5-66 million years ago, in the Late Cretaceous of North America. The name means "separated lizard" (referring to the arrangement of the cheek ...

'', which was thought of as a

senior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

of ''

Gryposaurus ''Gryposaurus'' (meaning "hooked-nosed (Ancient Greek, Greek ''grypos'') lizard"; sometimes incorrectly translated as "griffin (Latin ''gryphus'') lizard") was a genus of hadrosaur, duckbilled dinosaur that lived about 80 to 75 million years ag ...

'' at the time. In 1989, Michael Brett-Surman proposed the name Kritosaurini as a

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

of hadrosaurines that contained ''

Aralosaurus ''Aralosaurus'' was a genus of hadrosaurid dinosaur that lived during the Late Cretaceous in what is now Kazakhstan. It is known only by a posterior half of a skull (devoid of its mandible) and some post-cranial bones found in the Bostobe Format ...

'', ''

Brachylophosaurus ''Brachylophosaurus'' ( or ) is a genus of hadrosaurid dinosaur that lived during the Late Cretaceous period of western North America. It was first named in 1953 by Charles Mortram Sternberg for a skull and skeleton he discovered in 1936 in th ...

'', ''

'', and ''Kritosaurus'' (including ''Gryposaurus''). It was not until 2014 that Albert Prieto-Márquez officially defined and diagnosed Kritosaurini as the most exclusive clade of hadrosaurids containing '' Kritosaurus navajovius'', '' Gryposaurus notabilis'', and ''

Naashoibitosaurus ostromi ''Naashoibitosaurus'' (from Navajo —"creek lizard") is a genus of hadrosaurid dinosaur that lived about 73 million years ago, in the Late Cretaceous, and was found in the Kirtland Formation of the San Juan Basin in New Mexico, United States ...

''. Madia ''et al.'' (2021) defined the term under PhyloCode as "the largest clade containing ''Kritosaurus navajovius'' but not ''Brachylophosaurus canadensis'', ''Edmontosaurus regalis'', ''Hadrosaurus foulkii'', ''Saurolophus osborni''. In 2022, Rozadilla ''et al''. described '' Huallasaurus'' and '' Kelumapusaura'', two new genera similar to kritosaurins. In their study, they analyzed the relationships of the Kritosaurini and Hadrosauridae as a whole. In a study the following year, Alarcón-Muñoz ''et al.'' implemented an updated version of the phylogenetic matrix of Rozadilla ''et al'', proposing the name Austrokritosauria for the clade of entirely South American saurolophines closely related to kritosaurins. This clade was defined as "the most inclusive clade containing ''Huallasaurus'' but not ''Gryposaurus''".

Palaeobiogeography

Alarcón-Muñoz ''et al''. (2023) suggested that austrokritosaurs shared an ancestor with the North American kritosaurins in the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

, about 85 million years ago, before dispersing into South America. This likely occurred via island chains and

rafting Rafting and whitewater rafting are recreational outdoor activities which use an inflatable raft to navigate a river or other body of water. This is often done on whitewater or different degrees of rough water. Dealing with risk is often a ...

. The South American

hadrosauroid Hadrosauroidea is a clade or superfamily of ornithischian dinosaurs that includes the "duck-billed" dinosaurs, or Hadrosauridae, and all dinosaurs more closely related to them than to ''Iguanodon''. Their remains have been recovered in Asia, Euro ...

'' Gonkoken'' appears to have diverged from North American hadrosauroids at an even earlier time, about 91 million years ago in the

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

. The North American

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

Alamosaurus ''Alamosaurus'' (; meaning "Ojo Alamo lizard") is a genus of titanosaurian sauropod dinosaurs containing a single known species, ''Alamosaurus sanjuanensis'', from the Maastrichtian age of the Late Cretaceous period in what is now southwestern ...

'' may have experienced a similar dispersal events from relatives in South America in the late

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

–early

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

References

{{Taxonbar, from=Q1936160 Dinosaur subfamilies Late Cretaceous dinosaurs

Classification

Subgroups

Palaeobiogeography

See also

References