Oldman Formation

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]

Oldman Formation
Stratigraphic range: Campanian, 77.5–76.5 Ma 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
Region	Western Canada Sedimentary Basin
Country	Canada
Type section
Named for	Oldman River
Named by	Russell, L.S. and Landes, R.W.
Year defined	1940[2]
Oldman Formation (Canada) Show map of Canada Oldman Formation (Alberta) Show map of Alberta

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

Dinosaurs of the Oldman Formation

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 Provincial 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]

Fossil content

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

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

Theropods of the Oldman Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Daspletosaurus	D. torosus		Lower	Several specimens with a complete skeleton	A tyrannosaurid
	D. wilsoni[8]		Upper	Two skulls with associated postcrania	A tyrannosaurid
Dromaeosaurus	Indeterminate			Teeth	A dromaeosaurid
cf. Hesperonychus[9]	Indeterminate			Foot claw	A dromaeosaurid or an avialan[10]
Paronychodon	Indeterminate			Teeth	A troodontid
Prismatoolithus[11]	P. levis			Partial clutch containing 12 eggs
Ricardoestesia	R. isosceles				Misreported
	Indeterminate			Teeth	A dromaeosaurid
Saurornitholestes	S. langstoni			Partial remains	A dromaeosaurid
Troodon	Dubious			Teeth, eggs, embryos	A dubious taxon of troodontid, most specimens formerly considered Troodon have been reassigned to other genera such as Stenonychosaurus
Struthiomimus	S. altus			Several specimens, including a nearly complete skeleton[12]	An ornithomimid

Ornithischians

Ornithischians of the Oldman Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Albertaceratops	A. nesmoi		Lower	Single Skull	A ceratopsid
Albertadromeus[13]	A. syntarsus		Upper		A thescelosaurid
Anchiceratops	Indeterminate				A ceratopsid
Brachylophosaurus	B. canadensis		Upper	Skull And partial skeleton	A hadrosaurid
Chasmosaurus	C. brevirostris				Junior synonym of C. russelli
	C. russelli		Upper		A ceratopsid, also found in the Dinosaur Park Formation
Coronosaurus	C. brinkmani		Upper		A ceratopsid
Corythosaurus	C. casuarius		Upper		A hadrosaurid, also found in the Dinosaur Park Formation
Foraminacephale	F. brevis		Also known from the Dinosaur Park Formation[14]		A pachycephalosaurid, once thought to be a species of Stegoceras
Gremlin[15]	G. slobodorum		Lower	A right frontal	A leptoceratopsid
Hanssuesia	H. sternbergi		Upper, also present in the Dinosaur Park Formation and Judith River Formation	skull dome	A pachycephalosaurid, potentially synonymous with Stegoceras validum[16]
Maiasaura	M. peeblesorum		Upper		A hadrosaurid, also known from the Two Medicine Formation.[17]
Parasaurolophus	P. walkeri		Upper		A hadrosaurid, also found in the Dinosaur Park Formation
Scolosaurus	S. cutleri		Upper		An ankylosaurid, may actually be from the Dinosaur Park Formation
Wendiceratops	W. pinhornensis		Lower	Partial Skeleton And Partial Skull	A centrosaurine
An unnamed orodromine	Unnamed		Upper		An orodromine distinct from Albertadromeus. Closer to Oryctodromeus than to Albertadromeus, Orodromeus, and Zephyrosaurus.[13]

See also

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