Gryposaurus
Encyclopedia
Gryposaurus was a genus
of duckbilled dinosaur
that lived about 83 to 75.5 million years ago, in the Late Cretaceous
(late Santonian
to late Campanian
stages
) of North America
. Named species of Gryposaurus are known from the Dinosaur Park Formation
in Alberta
, Canada and the Lower Two Medicine Formation
in Montana
and the Kaiparowits Formation
of Utah
in the United States.
Gryposaurus is similar to Kritosaurus
, and for many years was regarded as the same genus. It is known from numerous skulls, some skeletons, and even some skin impressions that show it to have had pyramidal scales pointing out along the midline of the back. It is most easily distinguished from other duckbills by its narrow arching nasal hump, sometimes described as similar to a "Roman nose
," and which may have been used for species or sexual identification, and/or combat with individuals of the same species. A large bipedal/quadrupedal herbivore
around 9 meters long (30 ft), it may have preferred river
settings.
Gryposaurus was a hadrosaurid of typical size and shape; one of the best specimens of this genus, the nearly complete type specimen of Kritosaurus incurvimanus (now regarded as a synonym of Gryposaurus notabilis) came from an animal about 8.2 meters long (27 feet). This specimen also has the best example of skin impressions for Gryposaurus, showing this dinosaur to have had several different types of scalation: pyramidal, ridged, limpet
-shaped scutes upwards of 3.8 centimeters long (1.5 inches) on the flank and tail; uniform polygonal scales on the neck and sides of the body; and pyramidal structures, flattened side-to-side, with fluted sides, longer than tall and found along the top of the back in a single midline row.
The four named species of Gryposaurus differ in details of the skull and lower jaw. The prominent nasal arch found in this genus is formed from the paired nasal bone
s. In profile view, they rise into a rounded hump in front of the eyes, reaching a height as tall as the highest point of the back of the skull. The skeleton is known in great detail, making it a useful point of reference for other duckbill skeletons.
was once thought to fall into this group as well, before it was described (then known under the nickname "Antonio"). A subfamily, Gryposaurinae, was coined by Jack Horner
for it as part of a larger revision that promoted Hadrosaurinae to family status, but is not in use. The issue of its relationships to other hadrosaurs is equivocal anyway due to the lack of resolution on how it compares to Kritosaurus. At this time, the main differences between the two are location (Alberta and Montana for Gryposaurus, New Mexico
for Kritosaurus) and age (Kritosaurus comes from slightly younger rocks than Gryposaurus). Otherwise, the skull of Kritosaurus is incompletely known, lacking most of the bones in front of the eyes, but very similar to that of Gryposaurus.
specimen NMC
2278, a skull and partial skeleton collected in 1913 by George F. Sternberg
from what is now known as the Dinosaur Park Formation
of Alberta, along the Red Deer River
. This specimen was described and named by Lawrence Lambe
shortly thereafter, Lambe drawing attention to its unusual nasal crest. A few years earlier, Barnum Brown
had collected and described a partial skull from New Mexico, which he named Kritosaurus
. This skull was missing the snout, which had eroded into fragments; Brown restored it after the duckbill now known as Anatotitan
, which was flat-headed, and believed that some unusual pieces were evidence of compression. Lambe's description of Gryposaurus provided evidence of a different type of head, and by 1916 the Kritosaurus skull had been redone with a nasal arch and both Brown and Charles Gilmore had proposed that Gryposaurus and Kritosaurus were one and the same. Although this idea was not fully supported at the time, it was certainly in the air, as shown by William Parks's naming of a nearly complete skeleton from the Dinosaur Park Formation as Kritosaurus incurvimanus, not Gryposaurus incurvimanus (interestingly, he left Gryposaurus notabilis alone in its own genus). Frustratingly, this skeleton is missing the front part of the skull, ending just before the full shape of the nasal arch can be seen. The 1942 publication of the influential Lull
and Wright monograph
on hadrosaurs sealed the Kritosaurus/Gryposaurus question for nearly fifty years in favor of Kritosaurus. Reviews beginning in the 1990s, however, called into question the identity of Kritosaurus, which has limited material for comparison with other duckbills. Thus, Gryposaurus has once again been separated, at least temporarily, from Kritosaurus.
This situation is made more confusing by old suggestions by some authors, including Jack Horner, that Hadrosaurus
is also the same as either Gryposaurus, Kritosaurus, or both. This hypothesis
was most common in the late 1970s-early 1980s, and appears in some popular books; one well-known work, The Illustrated Encyclopedia of Dinosaurs, uses Kritosaurus for the Canadian material (Gryposaurus), but confusingly identifies the mounted skeleton of K. incurvimanus as Hadrosaurus in a photo caption. Although Horner in 1979 used the new combination Hadrosaurus [Kritosaurus] notabilis for a partial skull and skeleton and a second less-complete skeleton from the Bearpaw Shale of Montana (which have since fallen out of the literature), by 1990 he had changed his position, and was among the first to again use Gryposaurus in print. Current thought is that Hadrosaurus, although known from fragmentary material, can be distinguished from Gryposaurus by differences in the upper arm
and ilium
.
Further research has revealed the presence of a third species, G. latidens, from slightly older rocks in Montana than the classic gryposaur localities of Alberta. Based on two parts of a skeleton collected in 1916 for the American Museum of Natural History
, G. latidens is also known from bonebed
material. Horner, who described the specimens, considered to be a less derived
species.
New material from the Kaiparowits Formation
of Utah, in Grand Staircase-Escalante National Monument
, includes a skull and partial skeleton that represent the species G. monumentensis. Its skull was more robust than that of the other species, and its predentary
had enlarged prongs along its upper margin, where the lower jaw's beak was based. This new species greatly expands the geographic range of this genus, and there may be a second, more lightly built species present as well. Multiple gryposaur species are known from the Kaiparowits, from cranial and postcranial remains, and were larger than their northern counterparts.
Three named species are recognized today: G. notabilis, G. latidens, and G. monumentensis. The type species
G. notabilis is from the late Campanian
-age Upper Cretaceous Dinosaur Park Formation of Alberta, Canada. It is now thought to be the same as another species, G. incurvimanus from the same formation. The two had been differentiated by the size of the nasal arch (larger and closer to the eyes in G. notabilis) and the form of the upper arm (longer and more robust in G. incurvimanus). Ten complete skulls and twelve fragmentary skulls are known for G. notabilis along with postcrania
, as well as with two skeletons with skulls that had been assigned to G. incurvimanus. G. latidens, from the late Santonian
-early Campanian Lower Two Medicine Formation
of Pondera County
, Montana, USA, is known from partial skulls and skeletons from several individuals. Its nasal arch is prominent like that of G. notabilis, but farther forward on the snout, and its teeth are less derived
, reflecting iguanodont
-like characteristics. The informal name
"Hadrosauravus" is an early, unused name for this species. G. monumentensis is known from a skull and partial skeleton from Utah.
Scrappy remains
from Alberta originally named Trachodon (Pteropelyx) marginatus
were sometimes included with Kritosaurus under the "Kritosaurus=Gryposaurus" hypothesis. This taxon may be the same as G. notabilis, but this synonymy was not supported in the latest review. G. monumentensis was listed second on the top 10 list of new species in 2008 by the International Institute for Species Exploration
.
As a hadrosaurid
, Gryposaurus would have been a bipedal/quadruped
al herbivore
, eating a variety of plant
s. Its skull had special joints that 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 m (13 ft) above.
Like other bird-hipped dinosaurs
of the Dinosaur Park Formation, Gryposaurus appears to have only existed for part of the duration of time that the rocks were being formed. As the formation was being laid down, it recorded a change to more marine
-influenced conditions. Gryposaurus is absent from the upper part of the formation, with Prosaurolophus
present instead. Other dinosaurs known from only the lower part of the formation include the horned Centrosaurus
and the hollow-crested duckbill Corythosaurus
. Gryposaurus may have preferred river
-related settings.
ized skin, or that there was a cartilaginous
extension.
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 duckbilled 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...
that lived about 83 to 75.5 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...
(late Santonian
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 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
to late Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
stages
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
) 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...
. Named species of Gryposaurus are known from 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
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...
, Canada and the Lower Two Medicine Formation
Two Medicine Formation
The Two Medicine Formation is a geologic formation, or rock body, that was deposited between 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma , during Campanian time, and is located in northwestern Montana...
in Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
and the Kaiparowits Formation
Kaiparowits Formation
The Kaiparowits Formation is a sedimentary rock formation found in the Kaiparowits Plateau in Grand Staircase-Escalante National Monument, in the southern part of Utah in the western United States. It is over 2800 feet thick, and is Campanian in age...
of Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
in the United States.
Gryposaurus is similar to Kritosaurus
Kritosaurus
Kritosaurus is an incompletely known but historically important genus of hadrosaurid dinosaur. It lived about 73 million years ago, in the Late Cretaceous of North America...
, and for many years was regarded as the same genus. It is known from numerous skulls, some skeletons, and even some skin impressions that show it to have had pyramidal scales pointing out along the midline of the back. It is most easily distinguished from other duckbills by its narrow arching nasal hump, sometimes described as similar to a "Roman nose
Hooknose
]An Aquiline nose is a human nose with a prominent bridge, giving it the appearance of being curved or slightly bent...
," and which may have been used for species or sexual identification, and/or combat with individuals of the same species. A large bipedal/quadrupedal 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...
around 9 meters long (30 ft), it may have preferred river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
settings.
Description
Limpet
Limpet is a common name for a number of different kinds of saltwater and freshwater snails ; it is applied to those snails that have a simple shell which is more or less conical in shape, and either is not spirally coiled, or appears not to be coiled in the adult snails.The name limpet is most...
-shaped scutes upwards of 3.8 centimeters long (1.5 inches) on the flank and tail; uniform polygonal scales on the neck and sides of the body; and pyramidal structures, flattened side-to-side, with fluted sides, longer than tall and found along the top of the back in a single midline row.
The four named species of Gryposaurus differ in details of the skull and lower jaw. The prominent nasal arch found in this genus is formed from the paired nasal bone
Nasal bone
The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, "the bridge" of the nose.Each has two surfaces and four borders....
s. In profile view, they rise into a rounded hump in front of the eyes, reaching a height as tall as the highest point of the back of the skull. The skeleton is known in great detail, making it a useful point of reference for other duckbill skeletons.
Classification
Gryposaurus was a hadrosaurine hadrosaurid, a member of the duckbill subfamily without hollow head crests. The general term "gryposaur" is sometimes used for duckbills with arched nasals. TethyshadrosTethyshadros
Tethyshadros is a genus of hadrosauroid dinosaur from Italy.The genus was named and described by Italian paleontologist Fabio Marco Dalla Vecchia in 2009. Its only and type species is Tethyshadros insularis. The genus name refers to the Tethys Ocean and the Hadrosauroidea...
was once thought to fall into this group as well, before it was described (then known under the nickname "Antonio"). A subfamily, Gryposaurinae, was coined by Jack Horner
Jack Horner (paleontologist)
John "Jack" R. Horner is an American paleontologist who discovered and named Maiasaura, providing the first clear evidence that some dinosaurs cared for their young. He is one of the best-known paleontologists in the United States...
for it as part of a larger revision that promoted Hadrosaurinae to family status, but is not in use. The issue of its relationships to other hadrosaurs is equivocal anyway due to the lack of resolution on how it compares to Kritosaurus. At this time, the main differences between the two are location (Alberta and Montana for Gryposaurus, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
for Kritosaurus) and age (Kritosaurus comes from slightly younger rocks than Gryposaurus). Otherwise, the skull of Kritosaurus is incompletely known, lacking most of the bones in front of the eyes, but very similar to that of Gryposaurus.
Discovery and history
Gryposaurus is based onHolotype
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...
specimen NMC
National museums of Canada
National museums of Canada is the corporation name of the National Gallery of Canada, the Canadian Museum of Civilization, Canadian Museum of Nature and the National Museum of Science and Technology...
2278, a skull and partial skeleton collected in 1913 by George F. Sternberg
George F. Sternberg
George Fryer Sternberg was a paleontologist best known for his discovery in Gove County, Kansas of the "fish-within-a-fish" of Xiphactinus audax. He was the son of Charles Hazelius Sternberg and nephew of Brig. Gen. George M. Sternberg...
from what is now known as 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...
of Alberta, along 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...
. This specimen was described and named by Lawrence Lambe
Lawrence Lambe
Lawrence Morris Lambe was a Canadian geologist and palaeontologist from the Geological Survey of Canada .His published work, describing the diverse and plentiful dinosaur discoveries from the fossil beds in Alberta, did much to bring dinosaurs into the public eye and helped usher in the Golden...
shortly thereafter, Lambe drawing attention to its unusual nasal crest. A few years earlier, 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...
had collected and described a partial skull from New Mexico, which he named Kritosaurus
Kritosaurus
Kritosaurus is an incompletely known but historically important genus of hadrosaurid dinosaur. It lived about 73 million years ago, in the Late Cretaceous of North America...
. This skull was missing the snout, which had eroded into fragments; Brown restored it after the duckbill now known as Anatotitan
Anatotitan
Anatotitan is a genus of flat-headed or hadrosaurine hadrosaurid ornithopod dinosaur from the very end of the Cretaceous Period, in what is now North America...
, which was flat-headed, and believed that some unusual pieces were evidence of compression. Lambe's description of Gryposaurus provided evidence of a different type of head, and by 1916 the Kritosaurus skull had been redone with a nasal arch and both Brown and Charles Gilmore had proposed that Gryposaurus and Kritosaurus were one and the same. Although this idea was not fully supported at the time, it was certainly in the air, as shown by William Parks's naming of a nearly complete skeleton from the Dinosaur Park Formation as Kritosaurus incurvimanus, not Gryposaurus incurvimanus (interestingly, he left Gryposaurus notabilis alone in its own genus). Frustratingly, this skeleton is missing the front part of the skull, ending just before the full shape of the nasal arch can be seen. The 1942 publication of the influential Lull
R. S. Lull
Richard Swann Lull was an American paleontologist from the early 20th century, active at Yale University, who is largely remembered now for championing a Pre-Neo-Darwinian Synthesis view of evolution, whereby mutation could unlock mysterious genetic drives that, over time, would lead populations...
and Wright monograph
Monograph
A monograph is a work of writing upon a single subject, usually by a single author.It is often a scholarly essay or learned treatise, and may be released in the manner of a book or journal article. It is by definition a single document that forms a complete text in itself...
on hadrosaurs sealed the Kritosaurus/Gryposaurus question for nearly fifty years in favor of Kritosaurus. Reviews beginning in the 1990s, however, called into question the identity of Kritosaurus, which has limited material for comparison with other duckbills. Thus, Gryposaurus has once again been separated, at least temporarily, from Kritosaurus.
This situation is made more confusing by old suggestions by some authors, including Jack Horner, that 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...
is also the same as either Gryposaurus, Kritosaurus, or both. This hypothesis
Hypothesis
A hypothesis is a proposed explanation for a phenomenon. The term derives from the Greek, ὑποτιθέναι – hypotithenai meaning "to put under" or "to suppose". For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it...
was most common in the late 1970s-early 1980s, and appears in some popular books; one well-known work, The Illustrated Encyclopedia of Dinosaurs, uses Kritosaurus for the Canadian material (Gryposaurus), but confusingly identifies the mounted skeleton of K. incurvimanus as Hadrosaurus in a photo caption. Although Horner in 1979 used the new combination Hadrosaurus [Kritosaurus] notabilis for a partial skull and skeleton and a second less-complete skeleton from the Bearpaw Shale of Montana (which have since fallen out of the literature), by 1990 he had changed his position, and was among the first to again use Gryposaurus in print. Current thought is that Hadrosaurus, although known from fragmentary material, can be distinguished from Gryposaurus by differences in the upper arm
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
and ilium
Ilium (bone)
The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...
.
Further research has revealed the presence of a third species, G. latidens, from slightly older rocks in Montana than the classic gryposaur localities of Alberta. Based on two parts of a skeleton collected in 1916 for the American Museum of Natural 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...
, G. latidens is also known from bonebed
Bone bed
A bone bed is any geological stratum or deposit that contains bones of whatever kind. Inevitably, such deposits are sedimentary in nature. Not a formal term, it tends to be used more to describe especially dense collections...
material. Horner, who described the specimens, considered to be a less derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
species.
Kaiparowits Formation
The Kaiparowits Formation is a sedimentary rock formation found in the Kaiparowits Plateau in Grand Staircase-Escalante National Monument, in the southern part of Utah in the western United States. It is over 2800 feet thick, and is Campanian in age...
of Utah, in Grand Staircase-Escalante National Monument
Grand Staircase-Escalante National Monument
The Grand Staircase-Escalante National Monument contains 1.9 million acres of land in southern Utah, the United States. There are three main regions: the Grand Staircase, the Kaiparowits Plateau, and the Canyons of the Escalante. President Bill Clinton designated the area as a U.S. National...
, includes a skull and partial skeleton that represent the species G. monumentensis. Its skull was more robust than that of the other species, and its predentary
Predentary
The predentary is an 'extra' bone in the front of the lower jaw, which extended the dentary . It is found in the fossilised remains of ornithischian dinosaurs, which were herbivorous. The predentary coincided with the premaxilla in the upper jaw. Together they formed a beak-like apparatus used to...
had enlarged prongs along its upper margin, where the lower jaw's beak was based. This new species greatly expands the geographic range of this genus, and there may be a second, more lightly built species present as well. Multiple gryposaur species are known from the Kaiparowits, from cranial and postcranial remains, and were larger than their northern counterparts.
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...
G. notabilis is from the late Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
-age Upper Cretaceous Dinosaur Park Formation of Alberta, Canada. It is now thought to be the same as another species, G. incurvimanus from the same formation. The two had been differentiated by the size of the nasal arch (larger and closer to the eyes in G. notabilis) and the form of the upper arm (longer and more robust in G. incurvimanus). Ten complete skulls and twelve fragmentary skulls are known for G. notabilis along with postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
, as well as with two skeletons with skulls that had been assigned to G. incurvimanus. G. latidens, from the late Santonian
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 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
-early Campanian Lower Two Medicine Formation
Two Medicine Formation
The Two Medicine Formation is a geologic formation, or rock body, that was deposited between 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma , during Campanian time, and is located in northwestern Montana...
of Pondera County
Pondera County, Montana
-National protected area:*Lewis and Clark National Forest *Rocky Mountain Front Conservation Area -Demographics:As of the census of 2000, there were 6,424 people, 2,410 households, and 1,740 families residing in the county. The population density was 4 people per square mile . There were 2,834...
, Montana, USA, is known from partial skulls and skeletons from several individuals. Its nasal arch is prominent like that of G. notabilis, but farther forward on the snout, and its teeth are less derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
, reflecting iguanodont
Iguanodont
Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found...
-like characteristics. The informal name
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
"Hadrosauravus" is an early, unused name for this species. G. monumentensis is known from a skull and partial skeleton from Utah.
Scrappy remains
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
from Alberta originally named Trachodon (Pteropelyx) marginatus
Trachodon
Trachodon is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S.A...
were sometimes included with Kritosaurus under the "Kritosaurus=Gryposaurus" hypothesis. This taxon may be the same as G. notabilis, but this synonymy was not supported in the latest review. G. monumentensis was listed second on the top 10 list of new species in 2008 by the International Institute for Species Exploration
International Institute for Species Exploration
The International Institute for Species Exploration is a research institute hosted by Arizona State University, dedicated to improving taxonomical exploration and the cataloguing of new species of flora and fauna. It is located in Tempe, Arizona, in the United States of America. The institute's...
.
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...
, Gryposaurus 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 had special joints that 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 m (13 ft) above.
Like other bird-hipped dinosaurs
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
of the Dinosaur Park Formation, Gryposaurus appears to have only existed for part of the duration of time that the rocks were being formed. As the formation was being laid down, it recorded a change to more 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...
-influenced conditions. Gryposaurus is absent from the upper part of the formation, with Prosaurolophus
Prosaurolophus
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...
present instead. Other dinosaurs known from only the lower part of the formation include the horned Centrosaurus
Centrosaurus
Centrosaurus is a genus of herbivorous ceratopsian dinosaurs from the late Cretaceous of Canada. Their remains have been found in the Dinosaur Park Formation and uppermost Oldman Formation, dating from 76.5 to 75.5 million years ago....
and the hollow-crested duckbill 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...
. Gryposaurus may have preferred river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
-related settings.
Nasal arch
The distinctive nasal arch of Gryposaurus, like other cranial modifications in duckbills, may have been used for a variety of social functions, such as identification of sexes or species and social ranking. It could also have functioned as a tool for broadside pushing or butting in social contests, and there may have been inflatable air sacs flanking it for both visual and auditory signaling. The top of the arch is roughened in some specimens, suggesting that it was covered by thick, keratinKeratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
ized skin, or that there was a cartilaginous
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
extension.
External links
- Gryposaurus at DinoData
- Bureau of Land Management report on gryposaur skulls from Grand Staircase-Escalante National MonumentGrand Staircase-Escalante National MonumentThe Grand Staircase-Escalante National Monument contains 1.9 million acres of land in southern Utah, the United States. There are three main regions: the Grand Staircase, the Kaiparowits Plateau, and the Canyons of the Escalante. President Bill Clinton designated the area as a U.S. National...
, UtahUtahUtah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...