Oldman Formation

Oldman Formation Stratigraphic range: Upper Cretaceous, 77.5–76.5Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Belly River Group
Underlies	Dinosaur Park Formation
Overlies	Foremost Formation
Thickness	up to 328 feet (100 m)[1]
Lithology
Primary	Sandstone
Other	Mudstone and bentonite
Location
Coordinates	49°37′41″N 112°53′23″W / 49.62806°N 112.88972°W / 49.62806; -112.88972 (Oldman Formation)Coordinates: 49°37′41″N 112°53′23″W / 49.62806°N 112.88972°W / 49.62806; -112.88972 (Oldman Formation)
Region	Western Canada Sedimentary Basin
Country	Canada
Type section
Named for	Oldman River
Named by	Russell, L.S. and Landes, R.W., 1940.[2]

The Oldman Formation is a stratigraphic unit of Late Cretaceous (Campanian stage) age that underlies much of southern Alberta, Canada. It consists primarily of sandstones that were deposited in fluvial channel and floodplain environments. It was named for exposures along the Oldman River between its confluence with the St. Mary River and the city of Lethbridge, and it is known primarily for its dinosaur remains and other fossils.^[3]

Lithology

The Oldman Formation is composed primarily of light-colored, fine-grained sandstones. They are upward-fining, lenticular to sheet-like bodies that are yellowish, steep-faced and blocky in outcrop. The formation also includes lesser amounts of siltstone and mudstone.^[4]

Depositional Environments

The sediments of the Oldman Formation were deposited in fluvial channels (the sandstones) and a variety of channel margin, overbank and floodplain environments (the siltstones and mudstones). The formation is about 40 metres (130 ft) thick at Dinosaur Park in southeastern Alberta. It thickens toward the southwest, and northwestern Montana appears to have been the primary source of the sediments.^[4]

Relationship to other units

The Oldman Formation is a member of the Belly River Group (also known as the Judith River Group). It conformably overlies the Foremost Formation, and is separated from the overlying Dinosaur Park Formation by a regional disconformity. The sediments of the Oldman are superficially similar to those of the Dinosaur Park, which was included in the Oldman Formation prior to the recognition of the disconformity. The two formations can also be distinguished by petrographic and sedimentologic differences.^[3][4]

Age

The Oldman Formation was deposited during the middle Campanian, between about 77.5 and 76.5 million years ago.^[5] It lies fully within magnetic polarity Chron 33n.^[6]

Fauna

List of dinosaurs found in the formation:^[5][7]

Theropods

Theropods reported from the Oldman Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Daspletosaurus	D. torosus		Upper through lower	Several specimens	A tyrannosaurid	Daspletosaurus Dromaeosaurus Hesperonychus
Dromaeosaurus	Indeterminate			Teeth	A dromaeosaurid
Dromiceiomimus	D. brevitertius				Misreported
Elmisaurus	E. elegans				Misreported, found in the Dinosaur Park, Hell Creek, and Two Medicine Formations
Hesperonychus	H. elizabethae			Foot claw	A dromaeosaurid
Paronychodon	Indeterminate			Teeth	A troodontid
Ricardoestesia	R. isosceles				Misreported
	Indeterminate			Teeth	A dromaeosaurid
Saurornitholestes	S. langstoni			Partial remains	A dromaeosaurid
Troodon	T. formosus			Teeth, eggs, embryos	A troodontid, also found in the Dinosaur Park, Judith River, Lance, and Two Medicine Formations

Ornithischians

Ornithischians reported from the Oldman Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Albertaceratops	A. nesmoi		Lower		A ceratopsid	Albertaceratops Brachylophosaurus Chasmosaurus Parasaurolophus
Albertadromeus[8]	A. syntarsus		Upper		A thescelosaurid
Anchiceratops	Indeterminate				A ceratopsid
Brachylophosaurus	B. canadensis		Upper		A hadrosaurid
Coronosaurus	C. brinkmani		Upper		A ceratopsid
Chasmosaurus	C. brevirostris				Junior synonym of C. russelli.
	C. russelli		Upper		A ceratopsid, also found in the Dinosaur Park Formation
Corythosaurus	C. casuarius		Upper		A hadrosaurid, also found in the Dinosaur Park Formation
Euoplocephalus	E. tutus				An ankylosaurid, actually from the Dinosaur Park Formation.[9]
Gryposaurus	G. incurvimanus				Junior synonym of G. notabilis
	G. notabilis		Upper		A hadrosaurid, also found in the Dinosaur Park Formation
Hypacrosaurus	H. stebingeri				A hadrosaurid, actually from the Dinosaur Park Formation
"Laosaurus"[10]	"L." minimus[10]				An ornithopod, Nomen dubium.
Lambeosaurus	L. lambei				A hadrosaurid, actually from the Dinosaur Park Formation
Parasaurolophus	P. walkerii		Upper		A hadrosaurid, also found in the Dinosaur Park Formation
Scolosaurus	S. cutleri		Upper		An ankylosaurid, may actually be from the Dinosaur Park Formation

See also

• List of fossil sites (with link directory)
• List of dinosaur-bearing rock formations

Footnotes

References

• D.A. Eberth. 1996. Origin and significance of mud-filled incised valleys (Upper Cretaceous) in southern Alberta, Canada. Sedimentology 43:459–477
• Ryan, M. J., and Russell, A. P., 2001. Dinosaurs of Alberta (exclusive of Aves): In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 279–297.