Oldman Formation

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.

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 m 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.

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. In Central Montana, The Oldman Formation is equivalent to the upper part of the Mclelland Ferry Member, as well as the Woodhawk and Coal Ridge Members of the Judith River Formation. It is also believed to be equivalent to parts of the Two Medicine Formation in Western Montana.

Age

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

Fossil content

List of dinosaurs found in the formation:

Theropods

Ornithischians

References

Bibliography

• 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

References

1. Russell, L.S. and Landes, R.W., 1940. Geology of the southern Alberta Plains; [[Geological Survey of Canada]], Memoir 221.
2. [[Lexicon of Canadian Geological Units]]. "Oldman Formation".
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. (2025-09-10). "A potential deinocheirid ornithomimosaur from the Judith River Formation (Upper Cretaceous: Montana, U.S.A.) and its paleobiogeographic implications". Journal of Vertebrate Paleontology.
6. "A New Brachylophosaurin Hadrosaur (Dinosauria: Ornithischia) with an Intermediate Nasal Crest from the Campanian Judith River Formation of Northcentral Montana". PLOS One.
7. Arbour, V.M.. (2009). "A redescription of the ankylosaurid dinosaur ''Dyoplosaurus acutosquameus'' Parks, 1924 (Ornithischia: Ankylosauria) and a revision of the genus". Journal of Vertebrate Paleontology.
8. 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.
9. 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.
10. Warshaw, Elías A.. (2024-11-01). "Anagenesis and the tyrant pedigree: A response to "Re-analysis of a dataset refutes claims of anagenesis within ''Tyrannosaurus''-line tyrannosaurines (Theropoda, Tyrannosauridae)"". Cretaceous Research.
11. (2009). "A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America". Proceedings of the National Academy of Sciences.
12. (2019-07-10). "A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight". PeerJ.
13. (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.
14. (2015). "A redescription of ''Ornithomimus velox'' Marsh, 1890 (Dinosauria, Theropoda)". Journal of Vertebrate Paleontology.
15. (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.
16. Woodruff, D Cary. (2025-10-01). "The first pachycephalosaurid from the Late Cretaceous Two Medicine Formation: effects of the Western Interior Seaway on North American pachycephalosaurid evolution". Zoological Journal of the Linnean Society.
17. (2006). "Late Cretaceous vertebrates from the Western Interior".
18. (2023). "Windows into Sauropsid and Synapsid Evolution: Essays in Honor of Prof. Louis L. Jacobs". Dinosaur Science Center Press.
19. (2023). "Problematic putative pachycephalosaurids: Synchrotron µCT imaging shines new light on the anatomy and taxonomic validity of ''Gravitholus albertae'' from the Belly River Group (Campanian) of Alberta, Canada". Vertebrate Anatomy Morphology Palaeontology.
20. (22 December 2020). "First occurrence of Maiasaura (Dinosauria, Hadrosauridae) from the Upper Cretaceous Oldman Formation of southern Alberta, Canada". Canadian Journal of Earth Sciences.