Oldman Formation
Geologic formation in Canada
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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, | |
| 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)  Oldman Formation (Alberta) | |
Lithology
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 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] 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.[5] It is also believed to be equivalent to parts of the Two Medicine Formation in Western Montana.[6]
Age
Fossil content
List of dinosaurs found in the formation:[7][9]
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Theropods
| Theropods of the Oldman Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Gorgosaurus | G.sp. | Stratigraphic reassessment of material assigned to Gorgosaurus suggests there is a currently unnamed albertosaurine in the Oldman Formation[10] | ||||
| Daspletosaurus | D. torosus | Lower | Several specimens with a complete skeleton | A tyrannosaurid |  | |
| D. wilsoni[11] | Upper | Two skulls with associated postcrania | A tyrannosaurid | |||
| Dromaeosaurus | Indeterminate | Teeth | A dromaeosaurid |  | ||
| cf. Hesperonychus[12] | Indeterminate | Foot claw | A dromaeosaurid or an avialan[13] |  | ||
| Paronychodon | Indeterminate | Teeth | A troodontid | |||
| Prismatoolithus[14] | P. levis | Partial clutch containing 12 eggs | ||||
| Richardoestesia | 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[15] | 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[16] | A. syntarsus | Upper | A thescelosaurid |  | ||
| Anchiceratops | Indeterminate | A ceratopsid |  | |||
| Brachylophosaurus | B. canadensis | Upper | Skull and partial skeleton | A hadrosaurid |  | |
| Brontotholus | B. sp.[17] | Skull dome | A pachycephalosaurid, also found in the Two Medicine Formation |  | ||
| 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[18] | A pachycephalosaurid, once thought to be a species of Stegoceras |  | ||
| Gremlin[19] | 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[20] |  | |
| Maiasaura | M. peeblesorum | Upper | A hadrosaurid, also known from the Two Medicine Formation.[21] |  | ||
| 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.[16] | |||
See also
- List of fossil sites (with link directory)
- List of dinosaur-bearing rock formations