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Gryposaurus spp.
Topic Started: Aug 1 2013, 09:59 AM (2,214 Views)
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Gryposaurus spp.

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Temporal range: Late Cretaceous, 83-75.5Ma

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Dinosauria
Order: Ornithischia
Family: Hadrosauridae
Subfamily: Saurolophinae
Tribe: Kritosaurini
Genus: Gryposaurus Lambe, 1914

Species

  • G. notabilis Lambe, 1914 (type)
  • G. latidens Horner, 1992
  • G. monumentensis Gates & Sampson, 2007


Gryposaurus (meaning "hooked-nosed (Greek grypos) lizard"; sometimes incorrectly translated as "griffin (Latin gryphus) lizard") 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.

Description
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 three 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 bones. 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.
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G. notabilis restoration

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. Tethyshadros 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.

Discovery and history
Gryposaurus is based on 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.
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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.
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Skull, Royal Tyrrell Museum

Species
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.
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Restored head of G. notabilis.

Paleobiology
As a hadrosaurid, Gryposaurus would have been a bipedal/quadrupedal herbivore, eating a variety of plants. 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.
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Edited by Taipan, Aug 3 2013, 03:30 PM.
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'Vegetarian' Dinos Made Exception for Shellfish, Poop Study Shows

By Laura Geggel, Senior Writer | September 21, 2017 09:26am ET

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A black, knobby crustacean shell embedded in a piece of fossilized dinosaur poop
Credit: Karen Chin; Denver Museum of Nature and Science

Certain giant, herbivorous dinosaurs didn't eat just plants — they also chowed down on rotten logs harboring shellfish, a new study finds.

Researchers made this startling dietary discovery after examining 10 different specimens of fossilized dinosaur dung, known as coprolites, from the Kaiparowits Formation of Grand Staircase-Escalante National Monument in southern Utah.

"If we had found just one coprolite with crustacean pieces in it, that would have been interesting," said study lead researcher Karen Chin, an associate professor and a curator of paleontology at the University of Colorado Boulder. "But the fact that we found coprolites that spread out over at least 20 kilometers [12 miles] at different stratigraphic levels — that really strengthens our evidence for this being a behavior that these dinosaurs engaged in."

The coprolites with the crustacean shells — including what might be a crab shell — are filled with the remains of rotted wood, and date to between 76 million and 74 million years ago. Rotten wood is "kind of an unusual diet," Chin said, "but when you rot the wood, it increases the availability of cellulose [fiber] in the wood. Ranchers down in Chile have been known to open up rotted logs and their cattle just gravitate toward them and start feeding on the rotted wood."

It's possible that the dinosaurs ate the rotted wood to get fiber, as well as fungus and insects living in the rotted logs, Chin said. Of course, by eating the logs, the dinosaurs were also swallowing the crustaceans living in the damp, decomposing logs, but it's unclear whether the dinosaurs were purposefully or unintentionally eating the crustaceans, Chin said.

However, given that crustaceans are a good source of protein and calcium — a mineral needed during eggshell production — perhaps female dinosaurs were intentionally eating the crustaceans in preparation for laying eggs, a behavior also seen in breeding birds, Chin said.

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The surface of a crustacean shell embedded in a fragment of fossilized dinosaur dung
Credit: Karen Chin; Denver Museum of Nature and Science

It's unclear what type of Late Cretaceous dinosaur left the poop, but the formation was filled with the fossils of duck-billed dinosaurs, or hadrosaurs. Those dinosaurs' duck bills had teeth that were powerful enough to grind rotted logs, and so the droppings likely came from Gryposaurus, a 27-foot-long (8 meters) duck-billed dinosaur found at the site, Chin said.

What's more, the researchers wanted to make sure that the thick crustaceans were digested, as opposed to wandering into the dinosaur feces after the fact. But the evidence is fairly clear that the dinosaurs ingested the critters, Chin said.

"If the crustacean had just wandered in there, even if it had been stepped on by a dinosaur, it would mostly be together," Chin said. "These pieces of crab are scattered throughout the coprolites."

Chin noted that this is the first example on record of "fairly large" crustacean fragments in dinosaur coprolites. There are dinosaur coprolites from India containing teeny, tiny ostracods — crustaceans also known as seed shrimp — but these ostracods are just 0.04 inches to 0.08 inches (1 to 2 millimeters) long, while the fragments from this study are as large as 1.1 inches (3 centimeters) across, Chin said.

The study "kind of turns our stereotype of plant-eating dinosaurs on its head," said Steve Brusatte, a paleontologist at the University of Edinburgh in Scotland who was not involved in the research.

"When you cut into the coprolite of a plant-eating dinosaur, you expect to find only plants, so the crustaceans inside are a real surprise," Brusatte said.

Still, despite its shock value, the finding is not too unexpected, Brusatte said. "A lot of herbivores today also ingest animals, sometimes accidentally or sometimes to supplement their diet. These dinosaurs were no different."

The study was published online today (Sept. 21) in the journal Scientific Reports.




Journal Reference:
Karen Chin, Rodney M. Feldmann & Jessica N. Tashman Consumption of crustaceans by megaherbivorous dinosaurs: dietary flexibility and dinosaur life history strategies Scientific Reports 7, Article number: 11163 (2017) doi:10.1038/s41598-017-11538-w

Abstract
Large plant-eating dinosaurs are usually presumed to have been strictly herbivorous, because their derived teeth and jaws were capable of processing fibrous plant foods. This inferred feeding behavior offers a generalized view of dinosaur food habits, but rare direct fossil evidence of diet provides more nuanced insights into feeding behavior. Here we describe fossilized feces (coprolites) that demonstrate recurring consumption of crustaceans and rotted wood by large Late Cretaceous dinosaurs. These multi-liter coprolites from the Kaiparowits Formation are primarily composed of comminuted conifer wood tissues that were fungally degraded before ingestion. Thick fragments of laminar crustacean cuticle are scattered within the coprolite contents and suggest that the dinosaurian defecators consumed sizeable crustaceans that sheltered in rotting logs. The diet of decayed wood and crustaceans offered a substantial supply of plant polysaccharides, with added dividends of animal protein and calcium. Nevertheless, it is unlikely that the fossilized fecal residues depict year-round feeding habits. It is more reasonable to infer that these coprolites reflected seasonal dietary shifts—possibly related to the dinosaurs’ oviparous breeding activities. This surprising fossil evidence challenges conventional notions of herbivorous dinosaur diets and reveals a degree of dietary flexibility that is consistent with that of extant herbivorous birds.

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Journal Reference:
Filippo Bertozzo, Cristiano Dal Sasso, Matteo Fabbri, Fabio Manucci and Simone Maganuco. 2017. Redescription of A Remarkably Large Gryposaurus notabilis (Dinosauria: Hadrosauridae) from Alberta, Canada. Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 43.

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Two large raging bull gryposaurs fight for supremacy of the herd in violent clash on alluvial plains of Canada, 76 million years ago.
Bertozzo, Dal Sasso, Fabbri, et al., 2017. Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 43. Illustration: Davide Bonadonna. cienzafacile.it

Abstract
MSNM V345 is a partial skeleton of the North American hadrosaur species Gryposaurus notabilis, Lambe 1914, dis-covered in 1922 in the Dinosaur Park Formation of Dinosaur Provincial Park, Alberta, Canada. It was shipped in several crates to the Museo di Storia Naturale di Milano (MSNM), Italy, where it arrived in October 1958. Careless transportation during its long journey to Milan meant that the skeleton arrived extremely damaged and required heavy restoration work by MSNM staff.

A preliminary study of the specimen was conducted by Vittorio Vialli in 1960 while part of it was still under preparation. That study was followed by a more detailed, although still partial, osteological description by Giovanni Pinna in 1979. On the centennial of the species’ discovery, we decided to examine the specimen in even greater detail in order to improve knowledge on the dinosaur’s skeletal anatomy and help clarify the taxonomy of the genus.

Here, we redescribe the dinosaur’s osteology, focusing on unpublished elements, such as metapodials, phalanges, sacral vertebrae, and some caudal vertebrae, recently discovered to be located at the MSNM. Isolated appendicular elements found at the same quarry and tentatively referable to other individuals of the same taxon or to other dinosaur species are also briefly mentioned. Histological analysis of a core obtained from the femur revealed that it was made of fibrolamellar bone with a high number of Haversian systems. The presence of an external fundamental system indicates that the individual was fully adult at the moment of death.

Of note, the skeletal remains present with traces of at least four pathological conditions: a cavity in the predentary is speculated to be the result of osteomyelitis; the fifth dorsal vertebra is fused to the left rib through a overgrowth of bone, and is interpreted as osteosclerosis subsequent to a fracture; the neural spine of the 26th caudal vertebra is fractured and healed, and the centrum has a strap of bone growing up to the side of the preceding centrum, explainable as idiopathic skeletal hyperostosis.

A review of the skeletal reconstructions of the genus is also presented, followed by a summary of the skin remains and remarks on other anatomical traits. Altogether, the new data obtained on MSNM V345 have allowed us to present a more accurate and up-to-date skeletal reconstruction and in vivo restoration of G. notabilis.


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CONCLUSIONS:
Specimen MSNM V345 is a large, robust individual of Gryposaurus notabilis. Our re-examination of all its bones housed at the MSNM has allowed us to revise previous estimates on the completeness of the skeleton, which now reaches 32.68% (39.54% when taking into account the hid-den cranial bones, and 48.37% when duplicating existing counterlateral elements). The skull of MSNM V345 is one of the largest known for Gryposaurus. Our recalculation of the size of the skeleton, which takes into account the spaces occupied in vivo by intervertebral and epiphyseal cartilage, gives us an overall length of 800 cm in a neutral pose and a height at the hip of 315 cm. The osteology of the individual shows features related to other G. notabilis specimens: a dorsoventrally narrow orbit, infratemporal fenestra twice higher than wide, a well-developed nasal arch, wide and irregular ventral embayment of the jugal, a long and narrow quadratojugal, a predentary with nine large denticles placed asymmetrically, and a tall neural spine on the second caudal vertebra.

The advanced ontogenetic age of the skeleton – which likely belonged to a senile individual – is corroborated by palaeohistological analysis showing the presence of EFSs and several generations of Haversian systems in a femur, indicative of a specimen that was fully adult at time of death.

Finally, this individual was affected by several skele-tal disorders. The predentary bears a large, central fora-men located in the caudomedian plane of the bone. The histology of this anomaly reveals the presence of large resorption cavities and a randomised pattern of osteocytes, indicators of osteomyelitis. The transverse process of dorsal vertebra 5 is fused with the proximal region of the rib, affected by an abnormal overgrowth of bone tissue. CT-scanning of this vertebra indicates hyper-trophied osteosclerosis likely consequent to traumatic fracture. The caudal vertebrae 25 and 26 had their cen-tra fused together, with that of vertebra 25 broken into two halves. CT-scanning indicates that this condition might represent skeletal hyperostosis or haemangioma.

Gryposaurus notabilis is one of the first hadrosaurs depicted for the general audience. Nevertheless, it is not as popular as other duck-billed dinosaurs, such as Edmontosaurus, Parasaurolophus, or Corythosaurus. We have proposed new skeletal and in vivo restorations using the anatomical data obtained from our analysis.
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