Oldman Formation

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Oldman Formation
Stratigraphic range: Upper Cretaceous, 77.5–76.5Ma
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[edit]

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[edit]

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[edit]

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[edit]

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[edit]

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

Theropods[edit]

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

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[edit]

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

Albertaceratops

A. nesmoi

Lower

A ceratopsid

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[edit]

Footnotes[edit]

  1. ^ Lexicon of Canadian Geological Units. "Oldman Formation". 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. ^ a b 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. ^ a b c 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. ^ a b 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. ^ 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.  edit
  9. ^ Penkalski, P. (2013). "A new ankylosaurid from the late Cretaceous Two Medicine Formation of Montana, USA". Acta Palaeontologica Polonica. doi:10.4202/app.2012.0125.  edit
  10. ^ a b Gilmore, Charles W. (1924). "A new species of Laosaurus, an ornithischian dinosaur from the Cretaceous of Alberta". Transactions of the Royal Society of Canada, section 4, series 3 18: 1–6. 

References[edit]

  • 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.