Pete’s Pupa Peninsula (PPP): Middle Campanian - Late Campanian, Montana
collected 1993
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
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Reptilia
- Troodontidae
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Reptilia
- Elongatoolithidae
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unclassified
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| "akin to barattinia" | ||||||||||
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Celliformidae
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unclassified
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Skolithos sp.
Haldemann 1840
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| see common names | ||||||||||
Geography
| Country: | United States | State/province: | Montana | County: | Teton |
| Coordinates: | 47.8° North, 112.3° West (view map) | ||||
| Paleocoordinates: | 58.4° North, 69.0° West (Wright 2013) | ||||
| Basis of coordinate: | estimated from map | ||||
| Geographic resolution: | outcrop |
Time
| Period: | Cretaceous | Epoch: | Late Cretaceous |
| Stage: | Campanian | 10 m.y. bin: | Cretaceous 7 |
| Key time interval: | Middle Campanian - Late Campanian | ||
| Age range of interval: | 83.6 - 72.2 m.y. ago |
Stratigraphy
| Geological group: | Montana | Formation: | Two Medicine | Member: | Flag Butte |
| Stratigraphic resolution: | group of beds | ||||
| Stratigraphy comments: approx. 76.7 Ma; uppermost 2 m of outcrop | |||||
Lithology and environment
| Primary lithology: | "cross stratification",paleosol/pedogenic,intraclastic lime mudstone |
| Secondary lithology: | bioturbation,paleosol/pedogenic,gray,red mudstone |
| Includes fossils? | Y |
| Includes fossils? | Y |
| Lithology description: "Strata in the uppermost 2 m of the outcrop at PPP consist of alternating micritic limestones and mudstones of varying thicknesses (Figure 3). Limestone horizons range from nodular to thick (greater than 15 cm) with irregular upper and lower surfaces. Textures of the limestones vary. Horizons may contain few to abundant clastic grains. Thin sections of a trace fossil-bearing limestone reveal a cement-supported texture with an array of poorly sorted clasts ranging from silt to coarse sand, with most between silt and fine sand-sized particles. These represent lithic fragments, including volcanogenic sediments and quartz, whereas the matrix consists of micrite. Two horizons coarsen up over their 15–20 cm thickness to micritic sandstone. The variability and poor sorting of the textures together with the irregular nature of the horizons suggests that these limestones represent calcretes that formed within soils of various grain sizes. Mudstones vary in colour from medium to dark grey to blackish red. Some show minute (2–4 mm diameter) bioturbated textures in their upper 10–15 cm, which may be attributable to fossil root traces. Both rock types are massive to irregularly bedded. The top, 1.1–1.2m thick ledge-forming limestone includes a horizon with poorly defined ripple-scale cross stratification and thin (< 1–5 cm) mudstone beds. These mudstone interbeds pinch out toward the middle of the outcrop to the south, resulting in a coalescing of the irregularly bedded limestone into one unit. The lower surface of this unit truncates the underlying mudstone, contains small (, 1 – 2 cm) clasts from the underlying mudstone and has a channel-like form." | |
| Environment: | "floodplain" |
| Glacial or sequence phase: | regressive |
| Geology comments: facies located on Willow Creek anticline, described as "upland" facies; semiarid; layer resulted from a flooding event with "sediment gravity flows of uncertain genesis" | |
Taphonomy
| Modes of preservation: | body,trace |
| Size of fossils: | macrofossils |
| Spatial orientation: | life position |
| Preservation of anatomical detail: | good |
| Spatial resolution: | autochthonous |
Collection methods and comments
| Collection methods: | surface (in situ),field collection,observed (not collected) |
| Reason for describing collection: | paleoecologic analysis | Collection dates: | 1993 |
Metadata
| Also known as: | Willow Creek Anticline, WCA | ||
| Database number: | 223339 | ||
| Authorizer: | M. Carrano | Enterer: | M. Carrano |
| Modifier: | M. Carrano | Research group: | vertebrate |
| Created: | 2021-11-08 15:51:27 | Last modified: | 2025-02-22 15:12:02 |
| Access level: | the public | Released: | 2021-11-08 15:51:27 |
| Creative Commons license: | CC0 | ||
Reference information
Primary reference:
| 78546. | A. J. Martin and D. J. Varricchio. 2011. Paleoecological utility of insect trace fossils in dinosaur nesting sites of the Two Medicine Formation (Campanian), Choteau, Montana. Historical Biology 23(1):15-25 [M. Carrano/M. Carrano] |
Secondary references:
| 89709 | R. R. Rogers, J. R. Horner, J. Ramezani, E. M. Roberts, and D. J. Varricchio. 2024. Updating the Upper Cretaceous (Campanian) Two Medicine Formation of Montana: lithostratigraphic revisions, new CA-ID-TIMS U-Pb ages, and a calibrated framework for dinosaur occurrences. GSA Bulletin [M. Carrano/M. Carrano] |