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.[4] It is of Late Cretaceous age, Campanian to early Maastrichtian stage (Edmontonian Land-Mammal Age), and is composed of mudstone, sandstone, carbonaceousshales, 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.[2] It is overlain by the Battle and Scollard formations.[4] 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.[5] In more recent times, the Horseshoe Canyon Formation has become a major target for coalbed methane (CBM) production.
The Drumheller Coal Zone has been 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 is estimated there are 14 trillion cubic metres (500 tcf) of gas in place in all the coal in Alberta.
Biostratigraphy
The timeline below follows work by David A. Eberth and Sandra L. Kamo published in 2019.[7]
Dinosaurs
Ornithischians
Ankylosaurs
Ankylosaurs reported from the Horseshoe Canyon Formation
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.[8][13] Furthermore, all Horseshoe Canyon Formation ankylosaurine specimens were suggested to be reassigned to Anodontosaurus.[9]
Hadrosaurs
Hadrosaurs reported from the Horseshoe Canyon Formation
"[Five to ten] articulated skulls, some associated with postcrania, isolated skull elements, isolated postcranial elements, many individuals, embryo to adult."[14]
A maxilla, probable palatine, partial braincase, cervical vertebrae, dorsal vertebrae, caudal vertebrae, synsacrum, an anterior and a posterior cervical rib, a mid-dorsal rib, fragments of ilia, ischium, both pubes, partial tibia, and unidentifiable bones.[30]
A caenagnathid oviraptorosaur known from material previously assigned to Chirostenotes.[30]
Suggested from the skeleton of an immature tyrannosaurid (CMN 11315), thorough analysis of this specimen supports a referral to A. sarcophagus.[33] An isolated maxilla and teeth from an Edmontosaurus bonebed were also mistakenly referred to Daspletosaurus, however all the tyrannosaurid material in the bonebed was confirmed to belong to A. sarcophagus.[34]
^ abcdeArbour, Victoria (2010). "A Cretaceous armoury: Multiple ankylosaurid taxa in the Late Cretaceous of Alberta, Canada and Montana, USA". Journal of Vertebrate Paleontology. 30 (Supplement 2): 55A. doi:10.1080/02724634.2010.10411819.
^Paul Penkalski (2018). Revised systematics of the armoured dinosaur Euoplocephalus and its allies. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 287(3): 261-306. doi: https://doi.org/10.1127/njgpa/2018/0717
^ abcdSternberg, 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.
^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.
^Penkalski, P.; Blows, W. T. (2013). "Scolosaurus cutleri (Ornithischia: Ankylosauria) from the Upper Cretaceous Dinosaur Park Formation of Alberta, Canada". Canadian Journal of Earth Sciences. 50 (2): 171–182. Bibcode:2013CaJES..50..171P. doi:10.1139/cjes-2012-0098.
^ ab"Table 20.1," in Weishampel, et al. (2004). Page 441.
^ abBrown, B (1914). "Anchiceratops, a new genus of horned dinosaurs from the Edmonton Cretaceous of Alberta. With a discussion of the origin of the ceratopsian crest and the brain casts of Anchiceratops and Trachodon"". Bulletin of the American Museum of Natural History. 33: 539–548.
^ abcdeMallon, Jordan C.; Holmes, Robert; Eberth, David A.; Ryan, Michael J.; Anderson, Jason S. (2012). "Variation in the skull of Anchiceratops (Dinosauria, Ceratopsidae) from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta". Journal of Vertebrate Paleontology. 31 (5): 1047–1071. doi:10.1080/02724634.2011.601484. S2CID86349131.
^ abcdParks, W.A. (1925). "Arrhinoceratops brachyops, a new genus and species of Ceratopsia from the Edmonton Formation of Alberta". University of Toronto Studies, Geology Series 19:1-15
^Farke, A.A., 2007, "Cranial osteology and phylogenetic relationships of the chasmosaurine ceratopsid Torosaurus latus", pp 235-257 in: K. Carpenter (ed.), Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs, Bloomington, Indiana University Press
^ abcdWu, X-C.; Brinkman, D.B.; Eberth, D.A.; Braman, D.R. (2007). "A new ceratopsid dinosaur (Ornithischia) from the uppermost Horseshoe Canyon Formation (upper Maastrichtian), Alberta, Canada". Canadian Journal of Earth Sciences. 44 (9): 1243–1265. Bibcode:2007CaJES..44.1243W. doi:10.1139/E07-011.
^ abcBrown, B.; Schlaikjer, E. M. (1942). "The skeleton of Leptoceratops with the description of a new species". American Museum Novitates (1169): 1–15.
^ abcdP. J. Makovicky. 2001. A Montanoceratops cerorhynchus (Dinosauria: Ceratopsia) braincase from the Horseshoe Canyon Formation of Alberta. Mesozoic Vertebrate Life, D. H. Tanke and K. Carpenter (eds.), Indiana University Press, Bloomington 243-262
^ abcdeSternberg, C. M. (1950). "Pachyrhinosaurus canadensis, representing a new family of the Ceratopsia, from southern Alberta". National Museum of Canada Bulletin. 118: 109–120.
^ abcLongrich N. R.; Sankey J. T.; et al. (2010). "Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA". Cretaceous Research. 31 (2): 274–284. Bibcode:2010CrRes..31..274L. doi:10.1016/j.cretres.2009.12.002.
^ abcdeEvans, D.C., Cullen, T.M., Larson, D.W., and Rego, A. "A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada." Canadian Journal of Earth Sciences Early Online: 813-826. DOI: dx.doi.org/10.1139/cjes-2017-0034
^ abcdeLongrich, Nicholas R.; Currie, Philip J. (2009). "Albertonykus borealis, a new alvarezsaur (Dinosauria: Theropoda) from the Early Maastrichtian of Alberta, Canada: Implications for the systematics and ecology of the Alvarezsauridae". Cretaceous Research. 30 (1): 239–252. Bibcode:2009CrRes..30..239L. doi:10.1016/j.cretres.2008.07.005.
^ abcdeCurrie, P. J. and D. J. Varricchio (2004). "A new dromaeosaurid from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada". Pp. 112–132 in P. J. Currie, E. B. Koppelhus, M. A. Shugar and J. L. Wright. (eds.), Feathered Dragons. Indianapolis: Indiana University Press. [1]
^R. C. Fox and B. G. Naylor. 1986. A new species of Didelphodon Marsh (Marsupialia) from the Upper Cretaceous of Alberta, Canada: paleobiology and phylogeny. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 172(3):357-380
^X.-C. Wu, D. B. Brinkman, and A. P. Russell. 1996. A new alligator from the Upper Cretaceous of Canada and the relationships of early eusuchians. Palaeontology 39(2):351-375
^K. -Q. Gao and R. C. Fox. 1998. New choristoderes (Reptilia: Diapsida) from the Upper Cretaceous and Palaeocene, Alberta and Saskatchewan, Canada, a phylogenetic relationships of Choristodera. Zoological Journal of the Linnean Society 124:303-353
^B. Brown. 1913. A new plesiosaur, Leurospondylus, from the Edmonton Cretaceous of Alberta. Bulletin of the American Museum of Natural History 32(40):605-615
Makovicky, P. J., 2001, A Montanoceratops cerorhynchus (Dinosauria: Ceratopsia) braincase from the Horseshoe Canyon Formation of Alberta: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 243–262.
Varricchio, D. J. 2001. Late Cretaceous oviraptorosaur (Theropoda) dinosaurs from Montana. pp. 42–57 in D. H. Tanke and K. Carpenter (eds.), Mesozoic Vertebrate Life. Indiana University Press, Indianapolis, Indiana.
Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN0-520-24209-2.