Edmontonia

Edmontonia was an armoured dinosaur, part of the nodosaur family from the Late Cretaceous Period. It is named after the Edmonton Formation (now the Horseshoe Canyon Formation in Canada), the unit of rock it was found in.

Edmontonia
Temporal range: Late Cretaceous, 76.5–69 Ma
Edmontonia half
Mounted skeleton of E. rugosidens, specimen AMNH 5665
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Family: Nodosauridae
Genus: Edmontonia
Sternberg, 1928
Species
  • E. longiceps Sternberg, 1928 (type)
  • E. rugosidens (Gilmore, 1930 [originally Palaeoscincus rugosidens])
Synonyms
  • Chassternbergia Bakker, 1988

Description

Size and general build

Edmontonia Scale
Size comparison

Edmontonia was bulky, broad and tank-like. Its length has been estimated at about 6.6 m (22 ft).[1] In 2010, Gregory S. Paul considered both main Edmontonia species, E. longiceps and E. rugosidens, to be equally long at six metres and weigh three tonnes.[2]

Edmontonia had small, oval ridged bony plates on its back and head and many sharp spikes along its sides. The four largest spikes jutted out from the shoulders on each side, the second of which was split into subspines in E. rugosidens specimens. Its skull had a pear-like shape when viewed from above.[1] Its neck and shoulders were protected by three halfrings made of large keeled plates.

Distinguishing traits

Edmontonia dinosaur
Restoration of E. rugosidens

In 1990, Kenneth Carpenter established some diagnostic traits for the genus as a whole, mainly comparing it with its close relative Panoplosaurus. In top view, the snout has more parallel sides. The skull armour has a smooth surface. In the palate, the vomer is keeled. The neural arches and neural spines are shorter than those of Panoplosaurus. The sacrum proper consists of three sacral vertebrae. In the shoulder girdle, the scapula and coracoid are not fused.[3]

Carpenter also indicated in which way the main species differed from each other. The type species, Edmontonia longiceps, is distinguished from E. rugosidens in lacking sideways projecting osteoderms behind the eye sockets; having tooth rows that are less divergent; possessing a more narrow palate; having a sacrum that is wider than long and more robust; and in having shorter spikes at the sides. Also, an ossified cheek plate, known from E. rugosidens specimens, has not been found with Edmontonia longiceps.[3]

Skeleton

Edmontonia mount
Restored E. rugosidens skeleton without back armour

The skull of Edmontonia, up to half a metre long, is somewhat elongated with a protruding truncated snout. The snout carried a horny upper beak and the front snout bones, the premaxillae, were toothless. The cutting edge of the upper beak continued into the maxillary tooth rows, each containing fourteen to seventeen small teeth. In each dentary of the lower jaws, eighteen to twenty-one teeth were present. In the sides of the snout large depressions were present, "nasal vestibules", that each possessed two smaller openings. The top of these was a horizontal oval and represented the bony external nostril, the entrance to the nasal cavity, the normal air passage. The more rounded second opening below and obliquely in front, was the entrance to a "paranasal" tract, running along the outer side of the nasal cavity, in a somewhat lower position. A study by Matthew Vickaryous in 2006 proved for the first time the presence of multiple openings in a nodosaurid; such structures had already been well established in ankylosaurids. The air tracts are however, much simpler than in the typical ankylosaurid condition, and are not convoluted while lacking bony turbinate bones. The nasal cavity is separated into two halves along the midline by a bone wall. This septum is continued to below by the vomers, which are keeled, the keel featuring a pendulum-shaped appendage.[4] Another similarity with Ankylosauridae is the presence of a secondary bone palate, a possible case of parallel evolution. This has been shown too for Panoplosaurus.[3]

Edmontonia rugosidens armour AMNH 5381
The AMNH 5381 specimen of E. rugosidens, 1915 (first referred to Palaeoscincus by Matthew in 1922), showing the position of the dermal armour

The head armour tiles, or caputegulae, are smooth. Details differ between the various specimens but all share a large central nasal tile on the snout, bend large "loreal" tiles at the rear snout edges and a large central caputegula on the skull roof. The tiles behind the upper eye socket rim in Edmontonia longiceps do not stick out as much as in E. rugosidens, combined with a more narrow, pointed snout in the former. Some E. rugosidens specimens are known that possess a "cheek plate" above the lower jaw. Contrary to that discovered with Panoplosaurus, it is "free-floating", not fused with the lower jaw bone.[5]

The vertebral column contains about eight neck vertebrae, about twelve "free" back vertebrae, a "sacral rod" of four fused rear dorsal vertebrae, three sacral vertebrae, two caudosacrals and at least twenty, but probably about forty, tail vertebrae. In the neck the first two vertebrae, the atlas and axis, are fused. In the shoulder girdle, the coracoid has a rectangular profile, in contrast to the more rounded shape with Panoplosaurus. Two sternal plates are present, connected to sternal ribs. The forelimb is robust but relatively long. In Edmontonia longiceps and E. rugosidens the deltopectoral crest of the humerus is gradually rounded. The metacarpus is robust compared to that of Panoplosaurus. The hand very likely was tetradactyl, having four fingers.[3] The exact number of phalanges is unknown but the formula was by W.P. Coombs suggested to be 2-3-3-4-?.[6]

Osteoderms

Edmontonia Royal Tyrrell 1
Skull and neck armor
Edmontonia model
Edmontonia reconstruction in Royal Tyrrell Museum of Palaeontology

Apart from the head armour, the body was covered with osteoderms, skin ossifications. The configuration of the armour of Edmontonia is relatively well known, much of it having been discovered in articulation. The neck and shoulder region was protected by three cervical halfrings, each consisting of fused rounded rectangular, asymmetrically keeled, bone plates. These halfrings did not have a continuous underlying bone band. The first and second halfrings each had three pairs of segments. Below each lower end of the second halfring a side spike was present, a separate triangular osteoderm pointing obliquely forward. In the third halfring over the shoulders, the two pairs of central segments are bordered on each side by a very large forward-pointing spike that is bifurcated, featuring a secondary point above the main one. A third large spike behind it points more sideways; a smaller fourth one, often connected to the third at the base, is directed obliquely to behind. The row of side spikes is continued to the rear but there the osteoderms are much lower, curving strongly to behind, with the point overhanging the rear edge. Gilmore had trouble believing that the shoulder spikes really pointed to the front as this would have greatly hampered the animal while moving through vegetation. He suggested that the points had shifted during the burial of the carcass. However, Carpenter and G.S. Paul, trying to reposition the spikes, found that it was impossible to rotate them without losing conformity with the remainder of the armour. The side spikes have solid, not hollow, bases. The spikes differ in size between E. rugosidens individuals; those of the E. longiceps holotype are relatively small.[3]

Behind the third halfring the back and hip are covered by numerous transverse rows of much smaller oval keeled osteoderms. These are not ordered in longitudinal rows. The front rows have plates oriented along the length of the body, but to the rear the long axis of these osteoderms gradually rotates sideways, their keels ultimately running transversely. Rosettes are lacking. The configuration of the tail armour is unknown. The larger plates of all body parts were connected by small ossicles.[3] Such small round scutes also covered the throat.[4]

Discovery and species

Edmontonia restoration
Life restoration of two E. rugosidens from 1922, based on the 1915 AMNH specimen

In 1915, the American Museum of Natural History obtained the nearly complete, articulated front half of an armoured dinosaur, found the same year by Barnum Brown in Alberta, Canada. In 1922, William Diller Matthew referred this specimen, AMNH 5381, to Palaeoscincus in a popular-science article, not indicating any particular species.[7] It had been intended to name a new Palaeoscincus species in cooperation with Brown but their article was never published.[3] Matthew also referred specimen AMNH 5665, the front of a skeleton found by Levi Sternberg in 1917. In 1930 Charles Whitney Gilmore referred both specimens to Palaeoscincus rugosidens.[8] This species was based on type specimen USNM 11868, a skeleton found by George Fryer Sternberg in June 1928. The specific name is derived from Latin rugosus, "rough", and dens, "tooth". In 1940, Loris Shano Russell referred all three specimens to Edmontonia, as an Edmontonia rugosidens.[9]

Meanwhile, the type species of Edmontonia, Edmontonia longiceps, had been named by Charles Mortram Sternberg in 1928. The generic name Edmontonia refers to Edmonton or the Edmonton Formation. The specific name longiceps means "long-headed" in Latin. Its holotype is specimen NMC 8531, consisting of a skull, right lower jaw and much of the postcranial skeleton, including the armour. It was discovered near Morrin in 1924 by George Paterson, the teamster of the expedition led by C.M. Sternberg.[10]

Edmontonia species include:

  • E. longiceps, the type, known from a complete skull, is known from the middle Horseshoe Canyon Formation (Unit 2) which used to be dated to 71.5-71 million years ago.[11] This unit, which straddles the Campanian-Maastrichtian boundary, has since been recalibrated to an age of about 72 million years. Isolated bones and shed teeth from E. longiceps are also known from the upper Judith River Formation in Montana.
Edmontonia American Museum of Natural History
Left side of E. rugosidens specimen AMNH 5665
  • E. rugosidens. This species has been given its own genus, Chassternbergia, first coined as a subgenus by Dr. Robert Thomas Bakker in 1988, as Edmontonia (Chassternbergia) rugosidens and is based on differences in skull proportion from E. longiceps and its earlier time period.[5][12] It was given its full generic name in 1991 by George Olshevsky.[13] The name Chassternbergia honours Charles, "Chas", M. Sternberg. This subgenus or genus name is rarely applied.[14][15] E. rugosidens is found in the Campanian lower Dinosaur Park Formation, dating from about 76.5-75 million years ago.[11] Many later finds have been referred to E. rugosidens, among them CMN 8879, the top of a skull found in 1937 by Harold D'acre Robinson Lowe; ROM 433, a forked spine found by Jack Horner in 1986 among Oohkotokia material; ROM 5340, paired medial plates; ROM 1215, a skeleton; RTMP 91.36.507, a skull; RTMP 98.74.1, a possible Edmontonia skull; RTMP 98.71.1, a skeleton;[16] RTMP 98.98.01, a skull and right lower jaw; and RTMP 2001.12.158, a skull.[4]

Edmontonia schlessmani was a renaming in 1992 of Denversaurus schlessmani ("Schlessman's Denver lizard") by Adrian Hunt and Spencer Lucas.[17] This taxon was erected by Bakker in 1988 for a skull from the Late Maastrichtian Upper Cretaceous Lance Formation of South Dakota, specimen DMNH 468 found by Philip Reinheimer in 1922. This type specimen of Denversaurus is in the collections of the Denver Museum of Natural History (now the Denver Museum of Nature and Science), Denver, Colorado for which the genus was named. The specific name honours Lee E. Schlessman, whose Schlessman Family Foundation sponsored the museum. Bakker described the skull as being much wider at the rear than Edmontonia specimens.[5] However, later workers explained this by its being crushed,[3] and considered the taxon a junior synonym of Edmontonia longiceps.[14] The Black Hills Institute has referred a skeleton from the Lance Formation to Denversaurus, nicknamed "Tank". It has the inventory number BHI 127327.[18] New research indicates that it is closely related to Panoplosaurus.[19]

Edmontonia australis was named by Tracy Lee Ford in 2000 on the basis of cervical scutes, the holotype NMMNH P-25063, a pair of medial keeled neck osteoderms from the Maastrichtian Kirtland Formation of New Mexico and the paratype NMMNH P-27450, a right middle neck plate.[12] Although later considered to a dubious name,[15] it is now considered a junior synonym of Glyptodontopelta mimus.[20]

The naming history was further complicated in 1971, when Walter Preston Coombs Jr renamed both Edmontonia species, into Panoplosaurus longiceps and Panoplosaurus rugosidens respectively.[21] The latter species, which due to its much more complete material has determined the image of Edmontonia, until 1940 thus appeared under the name of Palaeoscincus, and during the 1970s and 1980s was shown as "Panoplosaurus" until newer research revived the name Edmontonia.

In 2010, G.S. Paul suggested that E. rugosidens was the direct ancestor of Edmontonia longiceps and the latter was again the direct ancestor of E. schlessmani.[2]

Phylogeny

C.M. Sternberg originally did not provide a classification of Edmontonia. In 1930, L.S. Russell placed the genus in the Nodosauridae, which has been confirmed by subsequent analyses. Edmontonia was generally shown to be a derived nodosaurid, closely related to Panoplosaurus. Russell in 1940 named a separate Edmontoniinae. In 1988 Bakker proposed that the Edmontoniinae with the Panoplosaurinae should be joined into Edmontoniidae, the presumed sister group of the Nodosauridae within Nodosauroidea which he assumed not be ankylosaurians but the last surviving stegosaurians.[5] Exact cladistic analysis has not confirmed these hypotheses however, and the concepts of Edmontoniinae and Edmontoniidae are not in modern use.

The following cladogram shows the position of Edmontonia in the nodosaurid evolutionary tree according to an analysis in 2011 by paleontologists Richard Stephen Thompson, Jolyon C. Parish, Susannah C. R. Maidment and Paul M. Barrett.[22]

Nodosauridae

Antarctopelta

Mymoorapelta

Hylaeosaurus

Anoplosaurus

Tatankacephalus

Horshamosaurus

Polacanthinae

Gargoyleosaurus

Hoplitosaurus

Gastonia

Peloroplites

Polacanthus

Struthiosaurus

Zhejiangosaurus

Hungarosaurus

Animantarx

Niobrarasaurus

Nodosaurus

Pawpawsaurus

Sauropelta

Silvisaurus

Stegopelta

Texasetes

Edmontonia

Panoplosaurus

Paleobiology

Function of the armour

Edmontonia shoulder spikes
Close up of the shoulder spikes of AMNH 5665

The large spikes were probably used between males in contests of strength to defend territory or gain mates.[1] The spikes would also have been useful for intimidating predators or rival males, passive protection, or for active self-defense.[1] The large forward pointing shoulder spikes could have been used to run through attacking theropods.[2] Carpenter suggested that the larger spikes of AMNH 5665 indicated this was a male specimen, a case of sexual dimorphism. However, he admitted the possibility of ontogeny, older individuals having longer spikes, as the specimen was relatively large.[3] Traditionally it had been assumed that to protect themselves from predators, nodosaurids like Edmontonia might have crouched down on the ground to minimize the possibility of attack to their defenseless underbelly, trying to prevent being flipped over by a predator.[2]

Paleoecology

Rings in the petrified wood of trees contemporary with Edmontonia show evidence of strong seasonal changes in precipitation and temperature;[1] this may hold an explanation for why so many specimens have been found with their armor plating and spikes in the same position they were in life.[1] The Edmontonia could have died due to drought, dried up, and then rapidly became covered in sediment when the rainy season began.[1]

Edmontonia rugosidens existed in the upper section of the Dinosaur Park Formation, about 76.5–75 million years ago. It lived alongside numerous other giant herbivores, such as the hadrosaurids Gryposaurus, Corythosaurus and Parasaurolophus, the ceratopsids Centrosaurus and Chasmosaurus, and ankylosaurids Scolosaurus[11] and Dyoplosaurus[11] Studies of the jaw anatomy and mechanics of these dinosaurs suggests they probably all occupied slightly different ecological niches in order to avoid direct competition for food in such a crowded eco-space.[23] The only large predators known from the same levels of the formation as Edmontonia are the tyrannosaurids Gorgosaurus libratus and an unnamed species of Daspletosaurus.[11]

Edmontonia longiceps is known from the Horseshoe Canyon Formation, from the middle unit, which was dated to 71.5-71 million years ago in 2009.[11] The fauna of the Horseshoe Canyon Formation is well-known, as vertebrate fossils, including those of dinosaurs, are quite common. Sharks, rays, sturgeons, bowfins, gars and the gar-like Aspidorhynchus made up the fish fauna. The saltwater plesiosaur Leurospondylus has been found in marine sediments in the Horseshoe Canyon, while freshwater environments were populated by turtles, Champsosaurus, and crocodilians like Leidyosuchus and Stangerochampsa. Dinosaurs dominate the fauna, especially hadrosaurs, which make up half of all dinosaurs known, including the genera Edmontosaurus, Saurolophus and Hypacrosaurus. Ceratopsians and ornithomimids were also very common, together making up another third of the known fauna. Along with much rarer ankylosaurians and pachycephalosaurs, all of these animals would have been prey for a diverse array of carnivorous theropods, including troodontids, dromaeosaurids, and caenagnathids.[24][25] Adult Albertosaurus was the apex predator in this environment, with intermediate niches possibly filled by juvenile albertosaurs.[24]

See also

References

  1. ^ a b c d e f g "Edmontonia." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 141. ISBN 0-7853-0443-6.
  2. ^ a b c d Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 238
  3. ^ a b c d e f g h i Carpenter, K. 1990. "Ankylosaur systematics: example using Panoplosaurus and Edmontonia (Ankylosauria: Nodosauridae)", In: Carpenter, K. & Currie, P.J. (eds) Dinosaur Systematics: Approaches and Perspectives, Cambridge University Press, Cambridge, pp. 281-298
  4. ^ a b c Vickaryous, Matthew K. (2006). "New information on the cranial anatomy of Edmontonia rugosidens Gilmore, a Late Cretaceous nodosaurid dinosaur from Dinosaur Provincial Park, Alberta". Journal of Vertebrate Paleontology. 26 (4): 1011–1013. doi:10.1671/0272-4634(2006)26[1011:niotca]2.0.co;2.
  5. ^ a b c d Bakker, R.T. (1988). Review of the Late Cretaceous nodosauroid Dinosauria: Denversaurus schlessmani, a new armor-plated dinosaur from the Latest Cretaceous of South Dakota, the last survivor of the nodosaurians, with comments on Stegosaur-Nodosaur relationships. Hunteria 1(3):1-23.(1988).
  6. ^ Coombs, W. P Jr.; Maryańska, T. (1990). "Ankylosauria". In Weishampel, D. P.; Dodson, P.; Osmólka, H. (eds.). The Dinosauria. University of California Press. pp. 456–483.
  7. ^ Matthew, W. D. (1922). "A superdreadnaught of the animal world—the armoured dinosaur Palaeoscincus". Natural History. 22: 333–342.
  8. ^ Gilmore, C.W. (1930). "On dinosaurian reptiles from the Two Medicine Formation of Montana". Proceedings of the United States National Museum. 77 (16): 1–39. doi:10.5479/si.00963801.77-2839.1.
  9. ^ Russell, L.S. (1940). "Edmontonia rugosidens (Gilmore), an armored dinosaur from the Belly River Series of Alberta". University of Toronto Studies, Geology Series. 43: 3–28.
  10. ^ Sternberg, C.M. (1928). "A new armored dinosaur from the Edmonton Formation of Alberta". Transactions of the Royal Society of Canada, Series 3. 22: 93–106.
  11. ^ a b c d e f Arbour, V.M.; Burns, M. E.; Sissons, R. L. (2009). "A redescription of the ankylosaurid dinosaur Dyoplosaurus acutosquameus Parks, 1924 (Ornithischia: Ankylosauria) and a revision of the genus". Journal of Vertebrate Paleontology. 29 (4): 1117–1135. doi:10.1671/039.029.0405.
  12. ^ a b Ford, T.L. (2000). A review of ankylosaur osteoderms from New Mexico and a preliminary review of ankylosaur armor. In: Lucas, S.G., and Heckert, A.B. (eds.). Dinosaurs of New Mexico. New Mexico Museum of Natural History and Science Bulletin 17:157-176.
  13. ^ G. Olshevsky, 1991, A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia, Mesozoic Meanderings 2, 268 pp
  14. ^ a b Vickaryous, M.K.; Maryańska, T. & Weishampel, D.B. (2004). "Ankylosauria". In Weishampel, D. B.; Dodson, P. & Osmólska, H. (eds.). The Dinosauria (Second Edition). University of California Press. pp. 363–392. ISBN 978-0-520-24209-8.
  15. ^ a b Carpenter K (2001). "Phylogenetic analysis of the Ankylosauria". In Carpenter, Kenneth (ed.). The Armored Dinosaurs. Indiana University Press. pp. 455–484. ISBN 978-0-253-33964-5.
  16. ^ Currie P.J., Russell D.A., 2005, "The geographic and stratigraphic distribution of articulated and associated dinosaur remains", In: Currie P.J., Koppelhus E.B., (editors). Dinosaur Provincial Park: A spectacular ancient ecosystem revealed. Bloomington: Indiana University Press. pp 537–569
  17. ^ Hunt, A.P. and Lucas, S.G., 1992, "Stratigraphy, Paleontology and age of the Fruitland and Kirkland Formations (Upper Cretaceous), San Juan Basin, New Mexico", New Mexico Geological Society Guidebook, 43rd Field Conference, San Juan Basin, volume 4, p. 217-240
  18. ^ Carpenter, K.; DiCroce, T.; Kinneer, B.; Simon, R. (2013). "Pelvis of Gargoyleosaurus (Dinosauria: Ankylosauria) and the Origin and Evolution of the Ankylosaur Pelvis". PLoS ONE. 8 (11): e79887. doi:10.1371/journal.pone.0079887. PMC 3828194. PMID 24244573.
  19. ^ Burns, ME. Intraspecific Variation in Late Cretaceous Nodosaurids (Ankylosauria: Dinosauria). Journal of Vertebrate Paleontology, Program and Abstracts, 2015, 99–100. ("Archived copy" (PDF). Archived from the original (PDF) on 2015-11-06. Retrieved 2015-10-30.CS1 maint: Archived copy as title (link))
  20. ^ Burns, Michael E. (2008). "Taxonomic utility of ankylosaur (Dinosauria, Ornithischia) osteoderms: Glyptodontopelta mimus Ford, 2000: a test case". Journal of Vertebrate Paleontology. 28 (4): 1102–1109. doi:10.1671/0272-4634-28.4.1102.
  21. ^ Coombs, W.P. Jr., 1971, The Ankylosauria, Dissertation Columbia University, New York, 487 pp
  22. ^ Richard S. Thompson; Jolyon C. Parish; Susannah C. R. Maidment; Paul M. Barrett (2011). "Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora)". Journal of Systematic Palaeontology. 10 (2): 301–312. doi:10.1080/14772019.2011.569091.
  23. ^ Mallon, J. C., Evans, D. C., Ryan, M. J., & Anderson, J. S. (2012). Megaherbivorous dinosaur turnover in the Dinosaur Park Formation (upper Campanian) of Alberta, Canada. Palaeogeography, Palaeoclimatology, Palaeoecology.
  24. ^ a b Eberth, D.A., 1997, "Edmonton group". In: Currie, P.J., Padian, K. (Eds.), Encyclopedia of Dinosaurs. Academic Press, New York, pp. 199–204
  25. ^ Larson, Derek W.; Brinkman, Donald B.; Bell, Phil R. (2010). "Faunal assemblages from the upper Horseshoe Canyon Formation, an early Maastrichtian cool-climate assemblage from Alberta, with special reference to the Albertosaurus sarcophagus bonebed". Canadian Journal of Earth Sciences. 47 (9): 1159–1181. doi:10.1139/e10-005.
Aguja Formation

The Aguja Formation is a geological formation in North America, exposed in Texas, United States and Chihuahua and Coahuila in Mexico, whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.

Animantarx

Animantarx ( ann-i-MAN-tarks; meaning 'living citadel') is a genus of nodosaurid ankylosaurian dinosaur from the Upper Cretaceous of western North America. Like other nodosaurs, it would have been a slow-moving quadrupedal herbivore covered in heavy armor scutes, but without a tail club. The skull measures approximately 25 cm (10 inches) in length, suggesting the animal as a whole was no more than 3 meters (10 feet) long.

Ankylosauria

Ankylosauria is a group of mainly herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are known to have first appeared in the early Jurassic Period, and persisted until the end of the Cretaceous Period. They have been found on every continent. The first dinosaur discovered in Antarctica was the ankylosaurian Antarctopelta, fossils of which were recovered from Ross Island in 1986.

Ankylosauria was first named by Henry Fairfield Osborn in 1923. In the Linnaean classification system, the group is usually considered either a suborder or an infraorder. It is contained within the group Thyreophora, which also includes the stegosaurs, armored dinosaurs known for their combination of plates and spikes.

Antarctopelta

Antarctopelta ( ann-TARK-toh-PEL-tə; meaning 'Antarctic shield') was a genus of ankylosaurian dinosaur with one known species, A. oliveroi, which lived in Antarctica during the Late Cretaceous Period. It was a medium-sized ankylosaur, reaching no more than 4 meters (13 ft) in length, and showed characteristics of two different families, making more precise classification difficult. The single known fossil specimen was discovered on James Ross Island in 1986, constituting the first dinosaur remains ever discovered on Antarctica, although it is the second dinosaur from the continent to be formally named.

Borealopelta

Borealopelta (meaning "Northern shield") is a genus of nodosaurid ankylosaur from the Early Cretaceous of Alberta, Canada. It contains a single species, B. markmitchelli, named in 2017 by Caleb Brown and colleagues from a well-preserved specimen known as the Suncor nodosaur. Discovered at an oil sands mine north of Fort McMurray, Alberta, that is owned by the Suncor Energy company, the specimen is remarkable for being among the best preserved dinosaur fossils of its size ever found. It preserved not only the armor (osteoderms) in their life positions, but also remains of their keratin sheaths, overlying skin, and stomach contents from the animal's last meal. Melanosomes were also found that indicate the animal had a reddish skin tone.

Charles Mortram Sternberg

Charles Mortram Sternberg (1885–1981) was an American-Canadian fossil collector and paleontologist, son of Charles Hazelius Sternberg.

Late in his career, he collected and described Pachyrhinosaurus, Brachylophosaurus, Parksosaurus and Edmontonia. A contemporary author wrote, "No published study of Canadian dinosaurs is possible today without citing one or another of Sternberg's papers."

Denversaurus

Denversaurus (meaning "Denver lizard") is a genus of herbivorous nodosaurid ankylosaurian dinosaur from the Late Cretaceous (late Maastrichtian) of western North America. Although at one point treated as a junior synonym of Edmontonia by some taxonomists, current research indicates that it is a distinct nodosaurid genus.

Ferris Formation

The Ferris Formation is a Late Cretaceous (~66 Ma) to Paleocene (66-63 Ma), fluvial-deltaic geological formation in southern Wyoming. It contains a variety of trace and body fossils, preserved in sandy fluvial channel deposits and overbank units. Dinosaur remains are fragmentary, but include Triceratops, Tyrannosaurus, dromaeosaurids, Paronychodon, Ricardoestesia, Edmontosaurus, Edmontonia, Ankylosaurus, and Pachycephalosaurus.Some of the fluvial channels contain evidence of tidal influence and brackish water, in the form of tidal facies, shark teeth, and shrimp burrows. This demonstrates that the western shoreline of the Western Interior Sea was still within a few hundred kilometers even during the latest Cretaceous. The local K-T boundary is contained within a sandy channel deposit made up of stacked bars. Reworked Cretaceous fossils are preserved at the base of the channel complex, associated with mud rip-up clasts, and Paleocene mammal fossils are preserved in the upper portion of the bar.

The Ferris Formation is up to 2,000 m thick in the Hanna Basin and represents rapid accumulation of predominantly fine-grained sediment on a broad delta. The delta previously fed the deepwater Lewis Shale and shallow marine Fox Hills Formation. The Ferris followed behind as a system of lagoons, bays, and delta plain environments.

Glyptodontopelta

Glyptodontopelta (meaning "Glyptodon shield", a reference to the similarity of its pelvic armor to that of Glyptodon) is a genus of dinosaur from the Late Cretaceous. It was a nodosaur, an armored dinosaur.

Fossils of Glyptodontopelta, consisting only of bony armor, were found in the U.S. state of New Mexico. The type species, Glyptodontopelta mimus, was described by Tracy Lee Ford in 2000. The holotype, USNM 8610, consists of three pieces of fused flat osteoderms, found in the Campanian-Maastrichtian Ojo Alamo Formation. It was concluded to be a dubious name, a nomen dubium, in a 2004 review of the Ankylosauria, but a 2008 publication by Michael Burns concurred with Ford that its armor was distinctive enough to consider it valid. Burns also assigned Glyptodontopelta to Nodosauridae — rejecting Ford's Stegopeltinae — and proposed that another armored taxon from New Mexico, Edmontonia australis, is a synonym of Glyptodontopelta mimus, based on analysis of armor size and shape.

Horseshoe Canyon Formation

The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.

The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230 metres (750 ft) thick. It is of Late Cretaceous age, Campanian to early Maastrichtian stage (Edmontonian Land-Mammal Age), and is composed of mudstone, sandstone, carbonaceous shales, and coal seams. A variety of depositional environments are represented in the succession, including floodplains, estuarine channels, and coal swamps, which have yielded a diversity of fossil material. Tidally-influenced estuarine point bar deposits are easily recognizable as Inclined Heterolithic Stratification (IHS). Brackish-water trace fossil assemblages occur within these bar deposits and demonstrate periodic incursion of marine waters into the estuaries.

The Horseshoe Canyon Formation crops out extensively in the area around Drumheller, as well as farther north along the Red Deer River near Trochu and along the North Saskatchewan River in Edmonton. It is overlain by the Battle, Whitemud, and Scollard formations. The Drumheller Coal Zone, located in the lower part of the Horseshoe Canyon Formation, was mined for sub-bituminous coal in the Drumheller area from 1911 to 1979, and the Atlas Coal Mine in Drumheller has been preserved as a National Historic Site. In more recent times, the Horseshoe Canyon Formation has become a major target for coalbed methane (CBM) production.

Dinosaurs found in the Horseshoe Canyon Formation include Albertavenator, Albertosaurus, Anchiceratops, Anodontosaurus, Arrhinoceratops, Atrociraptor, Epichirostenotes, Edmontonia, Edmontosaurus, Hypacrosaurus, Ornithomimus, Pachyrhinosaurus, Parksosaurus, Saurolophus, and Struthiomimus. Other finds have included mammals such as Didelphodon coyi, non-dinosaur reptiles, amphibians, fish, marine and terrestrial invertebrates and plant fossils. Reptiles such as turtles and crocodilians are rare in the Horseshoe Canyon Formation, and this was thought to reflect the relatively cool climate which prevailed at the time. A study by Quinney et al. (2013) however, showed that the decline in turtle diversity, which was previously attributed to climate, coincided instead with changes in soil drainage conditions, and was limited by aridity, landscape instability, and migratory barriers.

List of Appalachian dinosaurs

This is a list of dinosaurs whose remains have been recovered from Appalachia. During the Late Cretaceous period, the Western Interior Seaway divided the continent of North America into two landmasses; one in the west named Laramidia and Appalachia in the east. Since they were separated from each other, the dinosaur faunas on each of them were very different. For example, nodosaurs were common in Appalachia, but they were rare in Laramidia, and there were only specialized forms, such as Edmontonia and Panoplosaurus. This is an example of how isolated faunas develop differently.

March of the Dinosaurs

March of the Dinosaurs is a CGI film which has aired on ITV 1 in the UK on April 23, 2011 and released on DVD on 27 May 2011. The film was produced by Wide-Eyed Entertainment in association with Yap Films, and executive produced by Jasper James, who had previously worked on the Walking with... series and Prehistoric Park. Set 70 million years ago in the Cretaceous in North America, the film follows the journey of a young Edmontosaurus named Scar and his herd as they migrate south for the winter. This film depicts recent findings and speculation about dinosaurs, such as North-American Tyrannosaurs having feathers, and hunting in packs, dinosaurs in the snow and migrating.

It shows a 1000-mile autumn migration of Edmontosaurus and Pachyrhinosaurus from their summer grazing in northwest Canada (then well inside the Arctic Circle, so that the winter night and summer day were each 4 months long) to their winter grazing in the south-west USA, and the young Troodon which had to stay and endure the Arctic winter. The hazards met are land and water predators, an Arctic blizzard, thin ice, crossing a foodless volcanic wasteland, a lahar, and a wide river inhabited by predators. All the scenery and vegetation are CGI.

The DVD says that this is inspired by recent dinosaur fossil discoveries in the Canadian Arctic, and that the Arctic CGI trees are modelled on Sequioa.

Nodosauridae

Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period of what are now North America, Europe, Asia, Africa, and Antarctica.

Nodosaurinae

Nodosaurinae is a group of ankylosaurian dinosaurs named in 1919 by Othenio Abel.

Palaeoscincus

Palaeoscincus (meaning "ancient skink" from the Greek παλαιός and σκίγγος) is a dubious genus of ankylosaurian dinosaur based on teeth from the mid-late Campanian-age Upper Cretaceous Judith River Formation of Montana. Like several other dinosaur genera named by Joseph Leidy (Deinodon, Thespesius, and Trachodon), it is an historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists. Because of its wide use in the early 20th century, it was somewhat well known to the general public, often through illustrations of an animal with the armor of Edmontonia and the tail club of an ankylosaurid.

Panoplosaurus

Panoplosaurus (meaning "completely armoured lizard") is a genus of nodosaurid dinosaur. It was one of the last known nodosaurids, living during the Late Cretaceous in what is now North America; fossils have been located in Alberta, Canada.

Polacanthinae

Polacanthinae is a grouping of ankylosaurs, possibly primitive nodosaurids. Polacanthines are late Jurassic to early Cretaceous in age, and appear to have become extinct about the same time a land bridge opened between Asia and North America.Polacanthines were somewhat more lightly armoured than more advanced ankylosaurids and nodosaurids. Their spikes were made up of thin, compact bone with less reinforcing collagen than in the heavily armoured nodosaurids. The relative fragility of polacanthine armour suggests that it may have been as much for display as defense.

Stegopelta

Stegopelta (meaning "roofed shield") is a genus of armored dinosaur. It is based on a partial skeleton from the latest Albian-earliest Cenomanian-age Lower and Upper Cretaceous Belle Fourche Member of the Frontier Formation of Fremont County, Wyoming, USA.

Struthiosaurinae

Struthiosaurinae is a subfamily of ankylosaurian dinosaurs from the Cretaceous of Europe. It is defined as "the most inclusive clade containing Europelta but not Cedarpelta, Peloroplites, Sauropelta or Edmontonia" while being reinstated for a newly recognized clade of basal nodosaurids. Struthiosaurinae appeared at about exactly the same time as the North American subfamily Nodosaurinae. Struthiosaurines range all across the Cretaceous, the oldest genus being Europelta at an age of 112 Ma and the youngest being Struthiosaurus at about 85–66 Ma.

It was originally mentioned by Franz Nopcsa in 1923 as a subfamily of Acanthopholidae, along with the previously defined Acanthopholinae. The family has gone through many taxonomic revisions since it was defined by Nopcsa in 1902. It is now recognized as a junior synonym of the family Nodosauridae. The subfamily now includes the genera Anoplosaurus, Europelta, Hungarosaurus, and Struthiosaurus, designated as the type genus. Because of the instability of Acanthopholis, the generic namesake of Acanthopholinae, and its current identification as a nomen dubium, Struthiosaurinae, the next named group, was decidedly used over the older one.

A review of ankylosaur osteoderms was published in 2000, and reviewed the armour of Struthiosaurinae. The group was represented by the single genus Struthiosaurus, known from head, cervical, dorsal, sacral, and caudal scutes. Only a few head osteoderms were identified, so it is unknown how much of the skull was armoured. Many cervical and dorsal scutes have been preserved alongside species of Struthiosaurus. They include cervical bands, which are groups of osteoderms fused together and attached to the vertebrae, and large spines found on the shoulders of nodosaurids like Sauropelta and Edmontonia, although it is not known if the spines were fused like the later of separate like the former. It is quite possible that small ovoid scutes found on Struthiosaurus could have formed a pelvic shield like polacanthids. The caudal scutes of struthiosaurines are small and rough. Even though osteoderms are well-known, it is not certain where they were positioned on the body.

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