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
TypeGeological formation
Unit ofBelly River Group
UnderliesDinosaur Park Formation
OverliesForemost Formation
Thicknessup to 328 feet (100 m)[1]
Lithology
PrimarySandstone
OtherMudstone and bentonite
Location
Coordinates49°37′41″N 112°53′23″W
RegionWestern Canada Sedimentary Basin
Country Canada
Type section
Named forOldman River
Named byRussell, L.S. and Landes, R.W., 1940.[2]

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 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]

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 reported from the Oldman Formation
Genus Species Location Stratigraphic position Material Notes Images

Daspletosaurus

D. torosus

Upper through lower

Several specimens

A tyrannosaurid

Dromaeosaurus

Indeterminate

Teeth

A dromaeosaurid

Hesperonychus

H. elizabethae

Foot claw

A dromaeosaurid

Paronychodon

Indeterminate

Teeth

A troodontid

Prismatoolithus[8]

P. levis

Partial clutch containing 12 eggs.

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 Judith River 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

Albertadromeus[9]

A. syntarsus

Upper

A thescelosaurid

Anchiceratops

Indeterminate

A ceratopsid

Brachylophosaurus

B. canadensis

Upper

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

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

Wendiceratops

W. pinhornensis

Lower

A centrosaurine described in 2015

See also

Footnotes

  1. Lexicon of Canadian Geological Units. "Oldman Formation". Archived from the original on 2013-02-22. Retrieved 2009-02-06.
  2. Russell, L.S. and Landes, R.W., 1940. Geology of the southern Alberta Plains; Geological Survey of Canada, Memoir 221.
  3. Eberth, D.A. and Hamblin A.P. 1993. Tectonic, stratigraphic, and sedimentologic significance of a regional discontinuity in the upper Judith River Group (Belly River wedge) of southern Alberta, Saskatchewan, and northern Montana. Canadian Journal of Earth Sciences 30: 174-200.
  4. Eberth, D.A. 2005. The geology. In: Currie, P.J., and Koppelhus, E.B. (eds), Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press: Bloomington and Indianapolis, p. 54-82. ISBN 0-253-34595-2.
  5. Arbour, V.M.; Burns, M. E.; Sissons, R. L. (2009). "A redescription of the ankylosaurid dinosaur Dyoplosaurus acutosquameus Parks, 1924 (Ornithischia: Ankylosauria) and a revision of the genus". Journal of Vertebrate Paleontology. 29 (4): 1117–1135. doi:10.1671/039.029.0405.
  6. Lerbekmo, J.F. 1989. The position of the 33-33r (Campanian) polarity chron boundary in southeastern Alberta. Bulletin of Canadian Petroleum Geology 37: 43-47.
  7. Weishampel, D.B., Barrett, P.M., Coria, R.A., Le Loueff, J., Xu X., Zhao X., Sahni, A., Gomani, E.M.P., & Noto, C.N. 2004. Dinosaur distribution. In: Weishampel, D.B., Dodson, P., & Osmólska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 517-606.
  8. Zelenitsky, Darla K.; Hills, L.V. (1996). "An egg clutch of Prismatoolithus levis oosp. nov. from the Oldman Formation (Upper Cretaceous), Devil's Coulee, southern Alberta". Canadian Journal of Earth Sciences. 33 (8): 1127–1131. doi:10.1139/e96-085.
  9. Brown, C. M.; Evans, D. C.; Ryan, M. J.; Russell, A. P. (2013). "New data on the diversity and abundance of small-bodied ornithopods (Dinosauria, Ornithischia) from the Belly River Group (Campanian) of Alberta". Journal of Vertebrate Paleontology. 33 (3): 495. doi:10.1080/02724634.2013.746229.

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.
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