Horseshoe Canyon Formation

Horseshoe Canyon Formation
Stratigraphic range:
Horseshoe Canyon Formation at its type locality in Horseshoe Canyon, near Drumheller. The dark bands are coal seams.
Type	Geological formation
Unit of	Edmonton Group
Underlies	Whitemud Formation
Overlies	Bearpaw Formation
Thickness	Template:M to ft
Lithology
Primary	sandstone
Other	shale, coal
Location
Coordinates	51°25′24″N 112°53′18″W
Region	Western Canadian Sedimentary Basin
Country	Canada
Type section
Named for	Horseshoe Canyon
Named by	E.J.W. Irish, 1970

The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age (Edmontonian Land Mammal Age) and is composed of mudstone, sandstone, and carbonaceous shales. There are a variety of environments represented by the succession, including floodplains, estuarine channels, and coalswamps, which have yielded a diversity of fossil material. Tidally-influenced estuarine point bar deposits are easily recongizable 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 of Drumheller, Alberta, as well as further north along the Red Deer River near Trochu, and also in the city of 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, has been a primary CBM target for industry. In the area between Bashaw and Rockyford, the Drumheller Coal Zone is relatively shallow (about 300 metres) with 10 to 20 metres cumulative coal within a 70 to 120 metre coal zone thickness. The coal zone may contain 20 or more individual thin seams and interbedded sandstone and shale, which combine to make an attractive multi-completion CBM target for drilling companies. In total, it is estimated there are 14 trillion cubic metres (500 tcf) of gas in place in all the coal in Alberta.

Contact (red arrow) between the underlying marine shales of the Bearpaw Formation and the coastal Horseshoe Canyon Formation. Coal beds (black bands) are common in the Horseshoe Canyon Formation and were formed in coastal swamps.

Dinosaurs found in the Horseshoe Canyon Formation include Albertosaurus, Anchiceratops, Arrhinoceratops, Atrociraptor, Chirostenotes, Dromiceiomimus, Edmontonia, Edmontosaurus, Euoplocephalus, Hypacrosaurus, Ornithomimus, Pachyrhinosaurus, Parksosaurus, Saurolophus, Stegoceras, Struthiomimus and Troodon. 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 is thought to reflect the relatively cool climate which prevailed at the time.

Horseshoe Canyon itself is located 17 km southwest of Drumheller, Alberta, Canada, on Highway 9. This Canyon gets its name from its horseshoe shape and is approximately 3 km long, extending from Highway 9 to Kneehill Creek area.

Oil/gas production

Coalbed methane is extracted from the Horseshoe Canyon Formation in Southern Alberta.

Dinosaurs

Ankylosaurs

Ornithischians reported from the Horseshoe Canyon Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Edmontonia	E. longiceps					Euoplocephalus
Euoplocephalus	E. tutus

Maniraptors

Maniraptors reported from the Horseshoe Canyon Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Albertonykus	A. borealis			Limb bones, type specimen	An alvarezsaurid
Atrociraptor	A. marshalli			Partial skull, type specimen	A dromaeosaurid
Chirostenotes	C. pergracilis			A second metatarsal catalogued as NMC 2570.	A caenagnathid
Dromaeosaurus	Indeterminate			Teeth	A dromaeosaurid
Paronychodon	Indeterminate			Teeth	An indeterminate maniraptoran
Richardoestesia	R. gilmorei			Teeth	A dromaeosaurid
	R. isosceles			Teeth
Saurornitholestes	Indeterminate			Teeth	A dromaeosaurid
Troodon	Indeterminate			Teeth	A troodontid

Marginocephalians

Marginocephalians reported from the Horseshoe Canyon Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Anchiceratops	A. ornatus					Anchiceratops Pachyrhinosaurus lakustai
Arrhinoceratops	A. brachyops			"Complete skull."
Eotriceratops	E. xerinsularis‏		Found within the upper 20 m of the formation.
Pachyrhinosaurus	P. canadensis		Upper unit 1		Ceratopsids
	P. lakustai		Lower unit 1
Stegoceras	S. edmontonense				?Prenocephale.

Ornithomimids

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Ornithomimids reported from the Horseshoe Canyon Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Dromiceiomimus	D. brevitertius			Type specimen	Junior synonym of Ornithomimus edmontonicus.	Ornithomimus edmontonicus
Ornithomimus	O. brevitertius				Junior synonym of O. edmontonicus
	O. currellii				Junior synonym of O. edmontonicus
	O. edmontonicus			Several specimens, type specimen	An ornithomimid
	O. velox				Misclassified, now considered Struthiomimus sp.
Struthiomimus	Indeterminate				An ornithomimid
	S. brevitertius				Junior synonym of Ornithomimus edmontonicus
	S. currellii				Junior synonym of Ornithomimus edmontonicus
	S. ingens				Junior synonym of Ornithomimus edmontonicus

Ornithopods

Ornithopods reported from the Horseshoe Canyon Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Edmontosaurus	E. regalis					Hypacrosaurus Saurolophus
Hypacrosaurus	H. altispinus			"[Five to ten] articulated skulls, some associated with postcrania, isolated skull elements, isolated postcranial elements, many individuals, embryo to adult."
Parksosaurus	P. warrenae
Saurolophus	S. osborni			"Complete skull and skeleton, [two] complete skulls."

Tyrannosaurs

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Theropods reported from the Horseshoe Canyon Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Albertosaurus	A. arctunguis				Junior synonym of A. sarcophagus	Albertosaurus
	A. sarcophagus			Several skeletons and partial skeletons, type specimen	A tyrannosaurid
?Daspletosaurus	Indeterminate			Bonebed	A tyrannosaurid, may represent Albertosaurus sarcophagus
Deinodon	D. arctunguis				Junior synonym of Albertosaurus sarcophagus
	D. sarcophagus				Junior synonym of Albertosaurus sarcophagus
Dryptosaurus	D. incrassetus (formerly Laelaps)			Teeth	Nomen dubium

See also

• List of dinosaur-bearing rock formations

References

• 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. ISBN 0-520-24209-2.