# 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.

## 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 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.

## 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.

## 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:
| 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 | Stratigraphic position | Material | Notes |
| Daspletosaurus | D. torosus | Lower | Several specimens with a complete skeleton | A tyrannosaurid |
| Daspletosaurus | D. wilsoni | Upper | Two skulls with associated postcrania | A tyrannosaurid |
| Dromaeosaurus | Indeterminate | | Teeth | A dromaeosaurid |
| cf. Hesperonychus | Indeterminate | | Foot claw | A dromaeosaurid or an avialan |
| Paronychodon | Indeterminate | | Teeth | A troodontid |
| Prismatoolithus | P. levis | | Partial clutch containing 12 eggs | |
| Ricardoestesia | R. isosceles | | | Misreported |
| Ricardoestesia | 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 | An ornithomimid |

### Ornithischians

Ornithischians of the Oldman Formation :
| Genus | Species | Stratigraphic position | Material | Notes |
| Albertaceratops | A. nesmoi | Lower | Single Skull | A ceratopsid |
| Albertadromeus | 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 |
| Chasmosaurus | 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 | | A pachycephalosaurid, once thought to be a species of Stegoceras |
| Gremlin | 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 |
| Maiasaura | M. peeblesorum | Upper | | A hadrosaurid, also known from the Two Medicine Formation. |
| 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. |