Saurolophus
Encyclopedia
Saurolophus 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 dinosaur
s 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 biped
ally or quadruped
ally.
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
, is in press at this time, and a fourth species, S. kryschtofovici from China
, is considered dubious
.
Saurolophus is known from material including nearly complete skeletons, giving researchers a clear picture of its bony anatomy. S. osborni, the rarer Alberta
n species, was around 9.8 meters long (32 feet), with its skull a meter long (3.3 feet). It weight is estimated at 1.9 tonne
s (2.1 tons). S. angustirostris, the Mongolia
n species, was larger; the type
skeleton is roughly 12 meters long (39.4 ft), and larger remains are reported. Aside from size, the two species are virtually identical, with differentiation hindered by lack of study.
The most distinctive feature of Saurolophus is its cranial crest, which is present in young individuals but is smaller. It is long and spike-like and projects upward and backward at about a 45 degree angle, starting from over the eyes. This crest is often described as solid, but appears to be solid only at the point, with internal chambers that may have had a respiratory
and/or heat-regulation function.
, who described the first specimens, put it in its own subfamily in "Trachodontidae" (=Hadrosauridae), the Saurolophinae. At the time, this also included Corythosaurus
and Hypacrosaurus
, the only well-known examples of what would become Lambeosaurinae
. Brown thought that Saurolophus had an expanded tip to the ischium bone in the hip, as dinosaurs now recognized as lambeosaurines had, but this appears to have been based on a mistakenly associated lambeosaurine ischium. Additionally, he misinterpreted the crests of Saurolophus and lambeosaurines as being made of the same bones.
Most publications before 2010 classified Saurolophus as a member of Hadrosaurinae, often known colloquially as the "flat-headed hadrosaurs". In 2010, the subfamily Saurolophinae was brought back into use because Hadrosaurus
appears to have branched off prior to the "hadrosaurine"–lambeosaurine split. As a result, Hadrosaurinae by definition cannot include the traditional "hadrosaurines". Saurolophinae is the oldest available name for the former "hadrosaurine" clade
. Saurolophus, as the name suggests, is a saurolophine, as it has a saurolophine pelvis
and a (largely) solid crest.
Barnum Brown recovered the first described remains of Saurolophus in 1911, including a nearly complete skeleton (AMNH 5220
). Now on display in the American Museum of Natural History, this skeleton was the first nearly complete dinosaur skeleton from Canada. It was found in rocks of early Maastrichtian
age, in the Upper Cretaceous Horseshoe Canyon Formation
(then known as the Edmonton Formation) near Tolman Ferry on the Red Deer River
in Alberta. Brown wasted little time in describing his material, giving it its own subfamily. Saurolophus was an important early reference for other hadrosaurs, as seen in the names of Prosaurolophus ("before Saurolophus") and Parasaurolophus
("near Saurolophus"). However, little additional material has been recovered and described.
Instead, more abundant remains from Asia
have provided more data. Initial remains were not promising: a partial fragmentary ischium from Heilongjiang
, China
that Riabinin named S. kryschtofovici. Much better remains were soon recovered, though, but from Mongolia
's early Maastrichtian-age Nemegt Formation
. The 1947-49 Polish
-Mongolian
Paleontological Expedition recovered the large skeleton that became S. angustirostris as described by Anatoly Rozhdestvensky
. Other skeletons from a variety of growth stages have also been discovered, and S. angustirostris is now the most abundant Asian hadrosaurid.
In 1973, three partial skeletons were found in the Moreno Formation
of California
. These specimens were referred to cf. Saurolophus sp. In 2010, one of the skulls was instead assigned to Edmontosaurus
. A newer study placed the three specimens in a new species, S. "morrisi". Because the study has not yet been published, S. "morrisi" is currently a nomen nudum
.
Two species are regarded as valid today: the type species
S. osborni, and S. angustirostris. S. osborni (Brown, 1912) is known from a skull and skeleton, two other complete skulls, and skull fragments. S. angustirostris (Rozhdestvensky, 1952) is known from at least fifteen specimens. It differs from S. osborni by some details of the skull. For example, the Mongolian species had a longer skull (by 20%) and the front of the snout (the premaxilla
ry bones) were more upwardly-directed. S, kryschtofovici (Riabinin, 1930) is not considered valid; either it is regarded as a dubious
name, or as a synonym of S. angustirostris (although the name predates S. angustirostris). As noted above, S. "morrisi" is in press and is not yet official.
Parksosaurus
, ankylosaurid
Euoplocephalus
, nodosaurid
Edmontonia
, horned dinosaurs Montanoceratops
, Anchiceratops
, Arrhinoceratops
, and Pachyrhinosaurus
, pachycephalosaurid Stegoceras
, ostrich-mimics
Ornithomimus
and Struthiomimus
, a variety of poorly-known small theropods including troodontids
and dromaeosaurids
, and the tyrannosaurs
Albertosaurus
and Daspletosaurus
. The dinosaurs from this formation are sometimes known as Edmontonian, after a land mammal age
, and are distinct from those in the formations above and below. The Horseshoe Canyon Formation is interpreted as having a significant marine
influence, due to an encroaching Western Interior Seaway
, the shallow sea
that covered the midsection of North America through much of the Cretaceous
. S. osborni may have preferred to stay more landward.
S. angustirostris was one of the largest herbivores of the Nemegt Formation, which lacked large horned dinosaurs but had sauropods and a more diverse theropod fauna. It coexisted with the rare crested hadrosaurid Barsboldia
, flat-headed pachycephalosaurian Homalocephale
and domed Prenocephale
, the large ankylosaurid Tarchia
, rare saltasaurid
sauropods Nemegtosaurus
and Opisthocoelicaudia
, the alvarezsaurid
Mononykus
, three types of troodontids including Saurornithoides
, several oviraptorosauria
ns including Rinchenia
and Nomingia
, the ostrich-mimics Gallimimus
and Deinocheirus
, therizinosaur
id Therizinosaurus
, tyrannosaurid relative Bagaraatan
, and the tyrannosaurid Tarbosaurus
. Unlike other Mongolian formations like the well-known Djadochta Formation
that includes Velociraptor
and Protoceratops
, the Nemegt is interpreted as being well-watered, like the Dinosaur Park Formation
in Alberta.
As a hadrosaurid
, Saurolophus would have been a bipedal/quadruped
al herbivore
, eating a variety of plant
s. Its skull permitted a grinding motion analogous to chewing
, and its teeth
were continually replacing and packed into dental batteries that contained hundreds of teeth, only a relative handful of which were in use at any time. Plant material would have been cropped by its broad beak, and held in the jaws by a cheek
-like organ. Its feeding range would have extended from the ground to ~4 meter (13 ft) above. Common S. angustirostris would have been an important large herbivore in the Nemegt Formation
, but S. osborni was rare in the Horseshoe Canyon Formation
and faced competition from other duckbills (Edmontosaurus
and Hypacrosaurus
). Comparisons between the scleral ring
s of Saurolophus and modern birds and reptiles suggest that it may have been cathemeral
, active throughout the day at short intervals.
, and suggested it could provide an area for muscle attachment and a connection point for a nonbody back frill like that seen in the basilisk lizard
. Peter Dodson
interpreted similar features in other duckbills as having use in sexual identification. Maryańska and Osmólska, noting the hollow base, suggested that the crest increased the surface area of the respiratory cavity, and helped in thermoregulation. James Hopson
supported a function as a visual signal, and further mentioned the possibility that there were inflatable skin flaps over the nostrils that could have acted as resonators and additional visual signals. This idea has been picked up by authors of popular dinosaur works, such as David B. Norman
who discussed hadrosaurid display at length and included a life restoration of such an adaptation in action.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of large hadrosaurine
Hadrosaurinae
Saurolophinae is a subfamily of hadrosaurid dinosaurs. Members of the subfamily derive from the Late Cretaceous of Antarctica, Argentina, Canada , China, Kazakhstan, Mexico, Russia, the United States and...
duckbill
Hadrosaurid
Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper...
that lived about 69.5-68.5 million years ago, in the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
; it is one of the few genera of dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s 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 biped
Biped
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...
ally or quadruped
Quadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
ally.
The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, S. osborni, was described by Barnum Brown
Barnum Brown
Barnum Brown , a paleontologist born in Carbondale, Kansas, and named after the circus showman P.T. Barnum, discovered the second fossil of Tyrannosaurus rex during a career that made him one of the most famous fossil hunters working from the late Victorian era into the early 20th century.Sponsored...
in 1912 from Canadian
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
fossils. A second valid species, S. angustirostris, is represented by numerous specimens from Mongolia, and was described by Anatoly Konstantinovich Rozhdestvensky
Anatoly Konstantinovich Rozhdestvensky
Anatoly Konstantinovich Rozhdestvensky was a Russian paleontologist responsible for naming many dinosaurs, including Aralosaurus and Probactrosaurus....
. A third species, S. "morrisi" from California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, is in press at this time, and a fourth species, S. kryschtofovici from China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, is considered dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
.
Description
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
n species, was around 9.8 meters long (32 feet), with its skull a meter long (3.3 feet). It weight is estimated at 1.9 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s (2.1 tons). S. angustirostris, the Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
n species, was larger; the type
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
skeleton is roughly 12 meters long (39.4 ft), and larger remains are reported. Aside from size, the two species are virtually identical, with differentiation hindered by lack of study.
The most distinctive feature of Saurolophus is its cranial crest, which is present in young individuals but is smaller. It is long and spike-like and projects upward and backward at about a 45 degree angle, starting from over the eyes. This crest is often described as solid, but appears to be solid only at the point, with internal chambers that may have had a respiratory
Respiration (physiology)
'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
and/or heat-regulation function.
Classification
Barnum BrownBarnum Brown
Barnum Brown , a paleontologist born in Carbondale, Kansas, and named after the circus showman P.T. Barnum, discovered the second fossil of Tyrannosaurus rex during a career that made him one of the most famous fossil hunters working from the late Victorian era into the early 20th century.Sponsored...
, who described the first specimens, put it in its own subfamily in "Trachodontidae" (=Hadrosauridae), the Saurolophinae. At the time, this also included Corythosaurus
Corythosaurus
Corythosaurus is a genus of duck-billed dinosaur from the Upper Cretaceous Period, about 77-76.5 million years ago. It lived in what is now North America...
and Hypacrosaurus
Hypacrosaurus
Hypacrosaurus was a genus of duckbill dinosaur similar in appearance to Corythosaurus. Like Corythosaurus, it had a tall, hollow rounded crest, although not as large and straight...
, the only well-known examples of what would become Lambeosaurinae
Lambeosaurinae
Lambeosaurinae is a group of crested hadrosaurid dinosaurs.-Classification:Lambeosaurines have been split into Parasaurolophini and Corythosaurini . Corythosaurini and Parasaurolophini as terms entered the formal literature in Evans and Reisz's 2007 redescription of Lambeosaurus magnicristatus...
. Brown thought that Saurolophus had an expanded tip to the ischium bone in the hip, as dinosaurs now recognized as lambeosaurines had, but this appears to have been based on a mistakenly associated lambeosaurine ischium. Additionally, he misinterpreted the crests of Saurolophus and lambeosaurines as being made of the same bones.
Most publications before 2010 classified Saurolophus as a member of Hadrosaurinae, often known colloquially as the "flat-headed hadrosaurs". In 2010, the subfamily Saurolophinae was brought back into use because Hadrosaurus
Hadrosaurus
Hadrosaurus is a valid genus of hadrosaurid dinosaur. In 1858, a skeleton of a dinosaur from this genus was the first dinosaur skeleton known from more than isolated teeth to be found in North America. In 1868, it became the first ever mounted dinosaur skeleton...
appears to have branched off prior to the "hadrosaurine"–lambeosaurine split. As a result, Hadrosaurinae by definition cannot include the traditional "hadrosaurines". Saurolophinae is the oldest available name for the former "hadrosaurine" clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
. Saurolophus, as the name suggests, is a saurolophine, as it has a saurolophine pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
and a (largely) solid crest.
Discovery and history
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
). Now on display in the American Museum of Natural History, this skeleton was the first nearly complete dinosaur skeleton from Canada. It was found in rocks of early Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
age, in the Upper Cretaceous Horseshoe Canyon Formation
Horseshoe Canyon Formation
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales...
(then known as the Edmonton Formation) near Tolman Ferry on the Red Deer River
Red Deer River
The Red Deer River is a river in Alberta, Canada. It is a major tributary of the South Saskatchewan River.Red Deer River has a total length of and a drainage area of...
in Alberta. Brown wasted little time in describing his material, giving it its own subfamily. Saurolophus was an important early reference for other hadrosaurs, as seen in the names of Prosaurolophus ("before Saurolophus") and Parasaurolophus
Parasaurolophus
Parasaurolophus is a genus of ornithopod dinosaur that lived in what is now North America during the Late Cretaceous Period, about 76.5–73 million years ago. It was an herbivore that walked both as a biped and a quadruped. Three species are recognized: P. walkeri , P. tubicen, and the...
("near Saurolophus"). However, little additional material has been recovered and described.
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
have provided more data. Initial remains were not promising: a partial fragmentary ischium from Heilongjiang
Heilongjiang
For the river known in Mandarin as Heilong Jiang, see Amur River' is a province of the People's Republic of China located in the northeastern part of the country. "Heilongjiang" literally means Black Dragon River, which is the Chinese name for the Amur. The one-character abbreviation is 黑...
, China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
that Riabinin named S. kryschtofovici. Much better remains were soon recovered, though, but from Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
's early Maastrichtian-age Nemegt Formation
Nemegt Formation
The Nemegt Formation is a geological formation dating from the Late Cretaceous sedimentary from the Gobi Desert of Mongolia. It overlies and sometimes forms folds with the Barun Goyot Formation. It consists of river channel sediments and contains fossils of fish, turtles, crocodilians, birds and a...
. The 1947-49 Polish
Poles
thumb|right|180px|The state flag of [[Poland]] as used by Polish government and diplomatic authoritiesThe Polish people, or Poles , are a nation indigenous to Poland. They are united by the Polish language, which belongs to the historical Lechitic subgroup of West Slavic languages of Central Europe...
-Mongolian
Mongols
Mongols ) are a Central-East Asian ethnic group that lives mainly in the countries of Mongolia, China, and Russia. In China, ethnic Mongols can be found mainly in the central north region of China such as Inner Mongolia...
Paleontological Expedition recovered the large skeleton that became S. angustirostris as described by Anatoly Rozhdestvensky
Anatoly Konstantinovich Rozhdestvensky
Anatoly Konstantinovich Rozhdestvensky was a Russian paleontologist responsible for naming many dinosaurs, including Aralosaurus and Probactrosaurus....
. Other skeletons from a variety of growth stages have also been discovered, and S. angustirostris is now the most abundant Asian hadrosaurid.
In 1973, three partial skeletons were found in the Moreno Formation
Moreno Formation
The Moreno Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-Dinosaurs:-Mosasaurs:-Plesiosaurs:-Turtles:-See also:...
of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. These specimens were referred to cf. Saurolophus sp. In 2010, one of the skulls was instead assigned to Edmontosaurus
Edmontosaurus
Edmontosaurus is a genus of crestless hadrosaurid dinosaur. It contains two species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago,...
. A newer study placed the three specimens in a new species, S. "morrisi". Because the study has not yet been published, S. "morrisi" is currently a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
.
Species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
S. osborni, and S. angustirostris. S. osborni (Brown, 1912) is known from a skull and skeleton, two other complete skulls, and skull fragments. S. angustirostris (Rozhdestvensky, 1952) is known from at least fifteen specimens. It differs from S. osborni by some details of the skull. For example, the Mongolian species had a longer skull (by 20%) and the front of the snout (the premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
ry bones) were more upwardly-directed. S, kryschtofovici (Riabinin, 1930) is not considered valid; either it is regarded as a dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
name, or as a synonym of S. angustirostris (although the name predates S. angustirostris). As noted above, S. "morrisi" is in press and is not yet official.
Paleoecology
S. osborni shared the Horseshoe Canyon Formation with fellow hadrosaurids Edmontosaurus and hollow-crested Hypacrosaurus, hypsilophodontHypsilophodont
Hypsilophodonts were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the order of 1–2 meters long . They are known from Asia, Australia, Europe, New Zealand, North America, and South America, from rocks of Middle Jurassic to late Cretaceous age...
Parksosaurus
Parksosaurus
Parksosaurus was a genus of hypsilophodont ornithopod dinosaur from the early Maastrichtian-age Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada. It is based on most of a partially articulated skeleton and partial skull, showing it to have been a small, bipedal, herbivorous dinosaur...
, ankylosaurid
Ankylosauridae
An ankylosaurid is a member of the Ankylosauridae family of armored dinosaurs that evolved 125 million years ago and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event...
Euoplocephalus
Euoplocephalus
Euoplocephalus was one of the largest genera of ankylosaurian dinosaurs, at about the size of a small elephant. It is also the ankylosaurian with the best fossil record, so its extensive spiked armor, low-slung body and great club-like tail are well documented.-Description:Among the...
, nodosaurid
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:...
Edmontonia
Edmontonia
Edmontonia was an armoured dinosaur, a part of the nodosaur family from the Late Cretaceous Period. It is named after the Edmonton Formation , the unit of rock it was found in.-Description:...
, horned dinosaurs Montanoceratops
Montanoceratops
Montanoceratops was a genus of small ceratopsian dinosaur. It lived during the early Maastrichtian of the late Cretaceous Period...
, Anchiceratops
Anchiceratops
Anchiceratops is a genus of chasmosaurine ceratopsid dinosaur from the Late Cretaceous Period of western North America. Like other ceratopsids, it was a quadrupedal herbivore with three horns on its face, a parrot-like beak, and a long frill extending from the back of its head. The two horns above...
, Arrhinoceratops
Arrhinoceratops
Arrhinoceratops is a genus of ceratopsian dinosaur. The name was coined as its original describer concluded it had no nose-horn, however further analysis revealed this not to be the case...
, and Pachyrhinosaurus
Pachyrhinosaurus
Pachyrhinosaurus is a genus of ceratopsid dinosaurs from the Late Cretaceous period of North America. The first examples were discovered by Charles M. Sternberg in Alberta, Canada, in 1946, and named in 1950. Over a dozen partial skulls and a large assortment of other fossils from various species...
, pachycephalosaurid Stegoceras
Stegoceras
Stegoceras is a genus of plant-eating pachycephalosaurid dinosaur that lived in what is now North America during the Late Cretaceous period....
, ostrich-mimics
Ornithomimosauria
The Ornithomimosauria, ornithomimosaurs or ostrich dinosaurs were theropod dinosaurs which bore a superficial resemblance to modern ostriches. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia...
Ornithomimus
Ornithomimus
Ornithomimus is a genus of ornithomimid dinosaur from the Late Cretaceous Period of what is now North America.In 1890 Ornithomimus velox was named by Othniel Charles Marsh on the basis of a foot and partial hand from the Maastrichtian Denver Formation. Another seventeen species have been named since...
and Struthiomimus
Struthiomimus
Struthiomimus is a genus of ornithomimid dinosaur from the late Cretaceous of Alberta, Canada. It was a long-legged, ostrich-like dinosaur.The bipedal Struthiomimus stood about long and tall at the hips and weighed around...
, a variety of poorly-known small theropods including troodontids
Troodontidae
Troodontidae is a family of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and scrappy and they have therefore been allied, at various times, with many dinosaurian lineages...
and dromaeosaurids
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...
, and the tyrannosaurs
Tyrannosauridae
Tyrannosauridae is a family of coelurosaurian theropod dinosaurs which comprises two subfamilies containing up to six genera, including the eponymous Tyrannosaurus. The exact number of genera is controversial, with some experts recognizing as few as three...
Albertosaurus
Albertosaurus
Albertosaurus is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period, more than 70 million years ago. The type species, A. sarcophagus, was apparently restricted in range to the modern-day Canadian province of Alberta, after which...
and Daspletosaurus
Daspletosaurus
Daspletosaurus is a genus of tyrannosaurid theropod dinosaur that lived in western North America between 77 and 74 million years ago, during the Late Cretaceous Period. Fossils of the only named species were found in Alberta, although other possible species from Alberta and Montana await...
. The dinosaurs from this formation are sometimes known as Edmontonian, after a land mammal age
Faunal assemblage
Faunal Assemblage is the archaeological or paleontological term for a group of associated animal fossils found together in a given stratum.The principle of faunal succession is used in biostratigraphy to determine each biostratigraphic unit, or biozone...
, and are distinct from those in the formations above and below. The Horseshoe Canyon Formation is interpreted as having a significant marine
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
influence, due to an encroaching Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
, the shallow sea
Epeiric Sea
An epeiric sea is a shallow sea that extends over part of a continent.Epeiric seas are usually associated with the marine transgressions of the geologic past, which have variously been due to either global eustatic sea level changes, local tectonic deformation, or both, and are occasionally...
that covered the midsection of North America through much of the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. S. osborni may have preferred to stay more landward.
S. angustirostris was one of the largest herbivores of the Nemegt Formation, which lacked large horned dinosaurs but had sauropods and a more diverse theropod fauna. It coexisted with the rare crested hadrosaurid Barsboldia
Barsboldia
Barsboldia 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...
, flat-headed pachycephalosaurian Homalocephale
Homalocephale
Homalocephale is a genus of dinosaur belonging to the pachycephalosaurid family, which lived during the late Cretaceous period of what is now Mongolia, 80 million years ago. The genus was described in 1974 by Osmólska & Maryañska, and consists of a single species, H...
and domed Prenocephale
Prenocephale
Prenocephale was a small pachycephalosaurid dinosaur genus from the Late Cretaceous and was similar in many ways to its close relative, Homalocephale, which may simply represent Prenocephale juveniles. Adult Prenocephale probably weighed around and measured around long...
, the large ankylosaurid Tarchia
Tarchia
Tarchia is a genus of ankylosaurid dinosaur from the late Cretaceous of Mongolia. It is currently the geologically youngest known of all the Asian ankylosaurid dinosaurs and is represented by five or more specimens, including two complete skulls and one nearly complete postcranial skeleton...
, rare saltasaurid
Saltasauridae
Saltasauridae is a family of titanosaurian dinosaurs known from the late Cretaceous period of South America, Spain, Madagascar and Mongolia....
sauropods Nemegtosaurus
Nemegtosaurus
Nemegtosaurus was a sauropod dinosaur from Late Cretaceous Period of what is now Mongolia. It was named after the Nemegt Basin in the Gobi Desert, where the remains — a single skull — were found...
and Opisthocoelicaudia
Opisthocoelicaudia
Opisthocoelicaudia was 12-metre-long sauropod dinosaur of the Late Cretaceous Period discovered in Mongolia in 1965 by Polish and Mongolian scientists in what is now the Gobi Desert...
, the alvarezsaurid
Alvarezsauridae
Alvarezsauridae is an enigmatic family of small, long-legged running dinosaurs. Although originally thought to represent the earliest known flightless birds, a consensus of recent work suggests that they are primitive members of the Maniraptora. Other work found them to be the sister group to the...
Mononykus
Mononykus
Mononykus was a theropod dinosaur from late Cretaceous Mongolia with long, skinny legs. It moved about on two legs, was very nimble, and could run at high speeds, something that would have been useful in the open desert plains where it lived...
, three types of troodontids including Saurornithoides
Saurornithoides
Saurornithoides is a genus of troodontid maniraptoran dinosaur, living during the Late Cretaceous period. These creatures were predators, which could run fast on their hind legs and had excellent sight and hearing...
, several oviraptorosauria
Oviraptorosauria
Oviraptorosaurs are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot - like skulls, with or without bony crests atop the head...
ns including Rinchenia
Rinchenia
Rinchenia is a genus of Mongolian oviraptorid dinosaur from the late Cretaceous Period. The type species, Rinchenia mongoliensis, was originally classified as a species within the genus Oviraptor , but a re-examination by Barsbold in 1997 found differences significant enough to warrant a separate...
and Nomingia
Nomingia
Nomingia is a genus of oviraptorid theropod dinosaur hailing from the Late Cretaceous Bugin Tsav Beds of Mongolia.-Discovery and naming:...
, the ostrich-mimics Gallimimus
Gallimimus
Gallimimus is a genus of ornithomimid theropod dinosaur from the late Cretaceous period Nemegt Formation of Mongolia. With individuals as long as , it was one of the largest ornithomimosaurs...
and Deinocheirus
Deinocheirus
Deinocheirus is a genus of large theropod dinosaur, possibly an ornithomimosaurian, which lived in what is now southern Mongolia, during the late Cretaceous Period .-Discovery and naming:...
, therizinosaur
Therizinosaur
Therizinosaurs are theropod dinosaurs belonging to the clade Therizinosauria. Therizinosaur fossils have been found in Early through Late Cretaceous deposits in Mongolia, the People's Republic of China and Western North America...
id Therizinosaurus
Therizinosaurus
Therizinosaurus is a genus of very large theropod dinosaur. Therizinosaurus lived in the late Cretaceous Period , and was one of the last and largest representatives of its unique group, the Therizinosauria...
, tyrannosaurid relative Bagaraatan
Bagaraatan
Bagaraatan was a genus of theropod dinosaur from the Late Cretaceous period. Its fossils were found in the Nemegt Formation of Mongolia. Bagaraatan may have been around 3–4 metres in length....
, and the tyrannosaurid Tarbosaurus
Tarbosaurus
Tarbosaurus is a genus of tyrannosaurid theropod dinosaur that flourished in Asia about 70 million years ago, at the end of the Late Cretaceous Period. Fossils have been recovered in Mongolia, with more fragmentary remains found further afield in parts of China. Although many species have been...
. Unlike other Mongolian formations like the well-known Djadochta Formation
Djadochta Formation
The Djadochta Formation is situated in central Asia and dates from the Late Cretaceous Period. Laid down in the early Campanian, possibly starting in the latest Santonian, it is dated somewhat uncertainly at about 84-75 mya...
that includes Velociraptor
Velociraptor
Velociraptor is a genus of dromaeosaurid theropod dinosaur that existed approximately 75 to 71 million years ago during the later part of the Cretaceous Period. Two species are currently recognized, although others have been assigned in the past. The type species is V. mongoliensis; fossils...
and Protoceratops
Protoceratops
Protoceratops is a genus of sheep-sized herbivorous ceratopsian dinosaur, from the Upper Cretaceous Period of what is now Mongolia. It was a member of the Protoceratopsidae, a group of early horned dinosaurs...
, the Nemegt is interpreted as being well-watered, like the Dinosaur Park Formation
Dinosaur Park Formation
The Dinosaur Park Formation is the uppermost member of the Judith River Group, a major geologic unit in southern Alberta. It was laid down over a period of time between about 76.5 and 75 million years ago. The formation is made up of deposits of a high-sinuosity fluvial system, and is capped...
in Alberta.
Paleobiology
Hadrosaurid
Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper...
, Saurolophus would have been a bipedal/quadruped
Quadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
al herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
, eating a variety of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s. Its skull permitted a grinding motion analogous to chewing
Mastication
Mastication or chewing is the process by which food is crushed and ground by teeth. It is the first step of digestion and it increases the surface area of foods to allow more efficient break down by enzymes. During the mastication process, the food is positioned between the teeth for grinding by...
, and its teeth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...
were continually replacing and packed into dental batteries that contained hundreds of teeth, only a relative handful of which were in use at any time. Plant material would have been cropped by its broad beak, and held in the jaws by a cheek
Cheek
Cheeks constitute the area of the face below the eyes and between the nose and the left or right ear. They may also be referred to as jowls. "Buccal" means relating to the cheek. In humans, the region is innervated by the buccal nerve...
-like organ. Its feeding range would have extended from the ground to ~4 meter (13 ft) above. Common S. angustirostris would have been an important large herbivore in the Nemegt Formation
Nemegt Formation
The Nemegt Formation is a geological formation dating from the Late Cretaceous sedimentary from the Gobi Desert of Mongolia. It overlies and sometimes forms folds with the Barun Goyot Formation. It consists of river channel sediments and contains fossils of fish, turtles, crocodilians, birds and a...
, but S. osborni was rare in the Horseshoe Canyon Formation
Horseshoe Canyon Formation
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales...
and faced competition from other duckbills (Edmontosaurus
Edmontosaurus
Edmontosaurus is a genus of crestless hadrosaurid dinosaur. It contains two species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago,...
and Hypacrosaurus
Hypacrosaurus
Hypacrosaurus was a genus of duckbill dinosaur similar in appearance to Corythosaurus. Like Corythosaurus, it had a tall, hollow rounded crest, although not as large and straight...
). Comparisons between the scleral ring
Sclerotic ring
Sclerotic rings are rings of bone found in the eyes of several groups of vertebrate animals, except for mammals and crocodilians. They can be made up of single bones or small bones together. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical,...
s of Saurolophus and modern birds and reptiles suggest that it may have been cathemeral
Cathemeral
A cathemeral organism is one that has sporadic and random intervals of activity during the day or night in which food is acquired, socializing with other organisms occurs, and any other activities necessary for livelihood are performed...
, active throughout the day at short intervals.
Crest
The distinctive spike-like crest of Saurolophus has been interpreted in multiple ways, and could have had multiple functions. Brown compared it to the crest of a chameleonChameleon
Chameleons are a distinctive and highly specialized clade of lizards. They are distinguished by their parrot-like zygodactylous feet, their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues, their swaying gait, the possession by many of a...
, and suggested it could provide an area for muscle attachment and a connection point for a nonbody back frill like that seen in the basilisk lizard
Basiliscus (genus)
Basiliscus is a genus of large corytophanid lizards, commonly known as basilisks, which are endemic to southern Mexico, Central America, and northern South America.-Taxonomy and etymology:...
. Peter Dodson
Peter Dodson
Peter Dodson is an American paleontologist who has published many papers and written and collaborated on books about dinosaurs. An authority on Ceratopsians, he has also authored several papers and textbooks on hadrosaurs and sauropods, and is a co-editor of The Dinosauria, widely considered the...
interpreted similar features in other duckbills as having use in sexual identification. Maryańska and Osmólska, noting the hollow base, suggested that the crest increased the surface area of the respiratory cavity, and helped in thermoregulation. James Hopson
James Hopson
James Allen Hopson is an American paleontologist and professor at the University of Chicago. His work has focused on the evolution of the synapsids , and has been focused on the transition from basal synapsids to mammals, from the late Paleozoic through the Mesozoic Eras...
supported a function as a visual signal, and further mentioned the possibility that there were inflatable skin flaps over the nostrils that could have acted as resonators and additional visual signals. This idea has been picked up by authors of popular dinosaur works, such as David B. Norman
David B. Norman
David Bruce Norman is a British paleontologist, currently Director of the Sedgwick Museum, Cambridge University. He is a fellow at Christ's College, Cambridge where he teaches geology in the Natural Sciences tripos. He is a member of the Palaeontological Association. He has studied Iguanodon...
who discussed hadrosaurid display at length and included a life restoration of such an adaptation in action.