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50-585: The Horseshoe Canyon Formation is part of the Edmonton Group . In its type section (Red Deer River Valley at Drumheller ), it is ~250 metres (820 ft) thick, but further west the formation is older and thicker, exceeding 500 metres (1,600 ft) near Calgary . 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

100-563: A senior synonym of Ojoceratops from the Ojo Alamo Formation . Montanoceratops M. cerorhynchus Upper Tolman An isolated braincase. Edmonton Group Within the earth science of geology , the Edmonton Group is a Late Cretaceous ( Campanian stage ) to early Paleocene stratigraphic unit of the Western Canada Sedimentary Basin in the central Alberta plains. It

150-421: 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

200-801: 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

250-591: 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 ,

300-576: A maximum thickness of 763 metres (2,503 ft) near the foothills of the Rockies in the west, and thins eastward to zero at its erosional edge east of Edmonton. The Edmonton Group consists of fine-grained sandstones , calcareous sandstones, siltstones , sandy shales and mudstones , bentonitic sandstones and shales, bentonite beds, ironstone concretions, carbonaceous shales and coal seams. Hard sandstones commonly cap mesas , buttes and plateaus where erosion has formed badlands topography, as

350-513: 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

400-466: 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. Another similarity with Ankylosauridae

450-647: 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. Although later considered to a dubious name , it is now considered a junior synonym of Glyptodontopelta mimus. The naming history was further complicated in 1971, when Walter Preston Coombs Jr renamed both Edmontonia species, into Panoplosaurus longiceps and Panoplosaurus rugosidens respectively. The latter species, which due to its much more complete material has determined

500-414: A predator. Rings in the petrified wood of trees contemporary with Edmontonia show evidence of strong seasonal changes in precipitation and temperature; 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. The Edmontonia could have died due to drought, dried up, and then rapidly became covered in sediment when

550-464: A primary coalbed methane target for industry. In the area between Bashaw and Rockyford, the Coal Zone lies at relatively shallow depths (about 300 metres) and is about 70 to 120 metres thick. It contains 10 to 20 metres of cumulative coal, in up to 20 or more individual thin seams interbedded with sandstone and shale, which combine to make an attractive multi-completion CBM drilling target. In total, it

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600-437: 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 . The skull of Edmontonia , up to half

650-575: Is estimated there are 14 trillion cubic metres (500 tcf) of gas in place in all the coal in Alberta. The timeline below follows work by David A. Eberth and Sandra L. Kamo published in 2019. Anodontosaurus A. lambei Horsethief, Morrin, and lowest Tolman An ankylosaurine ankylosaurid also known from the middle Dinosaur Park Formation and closely related to Ankylosaurus . [REDACTED] Edmontonia E. longiceps Upper Horsethief A panoplosaurin nodosaurid also known from

700-552: 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. However, later workers explained this by its being crushed, and considered

750-528: Is known from the Horseshoe Canyon Formation , from the middle unit, which was dated to 71.5-71 million years ago in 2009. 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

800-399: 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. The exact number of phalanges is unknown but the formula was by W.P. Coombs suggested to be 2-3-3-4-?. Apart from the head armour,

850-597: Is the case for much of the Horseshoe Canyon Formation and the Scollard Formation. Coarse-grained sediments are rare in the Edmonton Group. Plant fossils are common in both the Late Cretaceous and early Paleocene portions of the Edmonton Group. Remains of Triceratops and other dinosaurs are found in the Late Cretaceous portion, especially the Horseshoe Canyon Formation and the lower part of

900-404: Is the presence of a secondary bone palate, a possible case of parallel evolution . This has been shown too for Panoplosaurus . 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

950-709: The 2018 phylogenetic analysis of Rivera-Sylva and colleagues shown below; limited to the relationships within Panoplosaurini . Animantarx Panoplosaurus Patagopelta Texasetes Denversaurus Edmontonia longiceps Edmontonia rugosidens The large spikes were probably used between males in contests of strength to defend territory or gain mates. The spikes would also have been useful for intimidating predators or rival males, passive protection, or for active self-defense. The large forward pointing shoulder spikes could have been used to run through attacking theropods. Carpenter suggested that

1000-870: The Fox Hills Formation in Saskatchewan. Formations that are stratigraphically equivalent in the western United States are the Horsethief Formation in Montana ; the Fox Hills Formation and Lance Formation in Montana; and the Lennup Formation and Muteetse Formation in Wyoming . The formations of the Edmonton Group are: Edmontonia Edmontonia is a genus of panoplosaurin nodosaurid dinosaur from

1050-873: The southern Alberta plains; into the upper part of the Wapiti Group in the northern Alberta and northeastern British Columbia ; and into the upper part of the Brazeau Formation and the Coalspur Formation in the foothills of the Canadian Rockies . It is equivalent to, but not contiguous with, the Eastend Formation , Whitemud Formation , Battle Formation and Frenchman Formation in the Cypress Hills of southeastern Alberta and southwestern Saskatchewan ; and with

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1100-571: 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,

1150-423: 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. The Drumheller Coal Zone has been

1200-499: 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

1250-893: The Late Cretaceous Period . It is part of the Nodosauridae , a family within Ankylosauria . It is named after the Edmonton Formation (now the Horseshoe Canyon Formation in Canada), the unit of rock where it was found. Edmontonia was bulky, broad and tank -like. Its length has been estimated at 6.6 m (22 ft). 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. 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

1300-491: The Scollard Formation, based on dinosaurian and microfloral evidence, as well as the presence of the terminal Cretaceous iridium anomaly . The Edmonton Group is present in the central plains of Alberta. It consists of sedimentary rocks that were deposited in nonmarine to brackish water environments between the Canadian Rockies in the west and the Western Interior Seaway to the east. Its reaches

1350-757: The Scollard Formation. Molluscs such as Ostrea and Unio are found in both portions. The Edmonton Group is disconformably overlain by the Paskapoo Formation and conformably overlies the Bearpaw Formation or, where the Bearpaw is absent, the Belly River Formation . The Edmonton Group grades into the sequence of the Blood Reserve Formation , St. Mary River Formation and Willow Creek Formation in

1400-802: 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 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

1450-491: 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

1500-578: 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. 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

1550-519: The front of a skeleton found by Levi Sternberg in 1917. In 1930 Charles Whitney Gilmore referred both specimens to Palaeoscincus rugosidens . 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 . Meanwhile,

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1600-489: The holotype specimen as Farke (2007) assigned the referred specimen ROM 1439 to Torosaurus . Eotriceratops E. xerinsularis Carbon Premaxillae, maxillae, rostral, supraorbital horncore with lacrimal, prefrontal, frontal, postorbital, jugal, epijugal, quadratojugal, quadrate, partial parietal, squamosal frill, braincase, syncervical, cervical vertebrae, dorsal vertebrae, ribs and fragments of ossified ligaments. A large chasmosaurine ceratopsid that may represent

1650-411: 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 . C.M. Sternberg originally did not provide

1700-401: 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. 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 . Edmontonia longiceps

1750-485: 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. 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

1800-463: 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. Such small round scutes also covered the throat. In 1915, the American Museum of Natural History obtained

1850-1281: The lower Dinosaur Park Formation and closely related Denversaurus . [REDACTED] Euoplocephalus E. tutus Walter Coombs (1971) synonymised Anodontosaurus lambei with E. tutus . However, recent studies suggest that Anodontosaurus is distinct enough from Euoplocephalus to be placed in its own genus and species. Furthermore, all Horseshoe Canyon Formation ankylosaurine specimens were suggested to be reassigned to Anodontosaurus . [REDACTED] Edmontosaurus E. regalis Horsethief; likely present in Drumheller. Hypacrosaurus H. altispinus Morrin and Tolman. "[Five to ten] articulated skulls, some associated with postcrania, isolated skull elements, isolated postcranial elements, many individuals, embryo to adult." Saurolophus S. osborni Upper Morrin and Tolman. "Complete skull and skeleton, [two] complete skulls." Anchiceratops A. ornatus Horsethief, Morrin, and Tolman; may have been present in Drumheller [Two] nearly complete skulls and [seven] partial skulls. A chasmosaurine ceratopsid contemporaneous and closely related to Arrhinoceratops . Arrhinoceratops A. brachyops Horsethief A nearly complete skull. A chasmosaurine ceratopsid restricted to

1900-509: 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. It had been intended to name a new Palaeoscincus species in cooperation with Brown but their article was never published. Matthew also referred specimen AMNH 5665,

1950-526: The presumed sister group of the Nodosauridae within Nodosauroidea which he assumed not be ankylosaurians but the last surviving stegosaurians. Exact cladistic analysis has not confirmed these hypotheses however, and the concepts of Edmontoniinae and Edmontoniidae are not in modern use. Edmontonia has been found as a close relative of Panoplosaurus in phylogenetic analysis, including in

2000-481: The rainy season began. 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 and Dyoplosaurus Studies of

2050-407: 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

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2100-415: 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. Its neck and shoulders were protected by three halfrings made of large keeled plates. 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,

2150-440: 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. Carpenter also indicated in which way the main species differed from each other. The type species, Edmontonia longiceps ,

2200-452: 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

2250-469: The taxon a junior synonym of Edmontonia longiceps . The Black Hills Institute has referred a skeleton from the Lance Formation to Denversaurus , nicknamed "Tank". It has the inventory number BHI 127327. New research indicates that it is closely related to Panoplosaurus . Edmontonia australis was named by Tracy Lee Ford in 2000 on the basis of cervical scutes, the holotype NMMNH P-25063,

2300-588: The teamster of the expedition led by C.M. Sternberg. Edmontonia species include: Edmontonia schlessmani was a renaming in 1992 of Denversaurus schlessmani ("Schlessman's Denver lizard ") by Adrian Hunt and Spencer Lucas . 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

2350-425: 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

2400-454: 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. The vertebral column contains about eight neck vertebrae, about twelve "free" back vertebrae,

2450-410: 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

2500-503: Was first described as the Edmonton Formation by Joseph Burr Tyrrell in 1887 based on outcrops along the North Saskatchewan River in and near the city of Edmonton . E.J.W. Irish later elevated the formation to group status and it was subdivided into four separate formations. In ascending order, they are the Horseshoe Canyon , Whitemud, Battle and Scollard Formations . The Cretaceous-Paleogene boundary occurs within

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