Where: Niobrara County, Wyoming (43.3° N, 104.3° W: paleocoordinates 49.2° N, 71.7° W)
• coordinate estimated from map
• small collection-level geographic resolution
When: Mitten Black Shale Member (Pierre Shale Formation), Campanian (83.6 - 72.1 Ma)
• bed-level stratigraphic resolution
Environment/lithology: offshore; lithified, concretionary, ferruginous, phosphatic, gray, calcareous shale
• "shale, dark gray, hard, hackly, forms bare outcrop, limonite stains on fracture surfaces give unit a dark rusty brown appearance. Unit contains dusky red and rusty weathering ironstone concretions at 10, 12, 19, 48, 131, 139, 145, and 153 ft above base, and grayish orange weathering septarian ls concretions at 10, 33, 60, 88 nad 179 ft above base. Ironstone concretions 48 ft above base have grayish orange weathering rinds of ls that show cone-in-cone structure. Grayish orange weathering phosphatic nodules occur sparsely 40 ft above base."
• "shale, dark gray, hard, hackly, forms bare outcrop, limonite stains on fracture surfaces give unit a dark rusty brown appearance. Unit contains dusky red and rusty weathering ironstone concretions at 10, 12, 19, 48, 131, 139, 145, and 153 ft above base, and grayish orange weathering septarian ls concretions at 10, 33, 60, 88 nad 179 ft above base. Ironstone concretions 48 ft above base have grayish orange weathering rinds of ls that show cone-in-cone structure. Grayish orange weathering phosphatic nodules occur sparsely 40 ft above base."
Reposited in the USGS
Collection methods: mechanical,
• "[collected] from concretions 19 ft above base."
Primary reference: J. R. Gill, W. A. Cobban, and P. M. Kier. 1966. The Red Bird Section of the Upper Cretaceous Pierre Shale in Wyoming. United States Geological Survey Professional Paper 393-A:1-73 [J. Alroy/M. Sommers/A. Clement]more details
Purpose of describing collection: biostratigraphic analysis
PaleoDB collection 1740: authorized by John Alroy, entered by Mike Sommers on 03.06.1999
Creative Commons license: CC BY (attribution)
Taxonomic list
• "The fossils are ordinarily well-preserved. Most of the cephalopod shells and the inner nacreous layer of Inoceramus are aragonitic, especially specimens from above the Red Bird Silty Member. Shell material and specimens from the Red Bird member and the upper 50' of the underlying Mitten Member is partially transformed to calcite...Ammonites...of the [mid-upper third] of the Mitten Member are...entirely aragonite whereas shell material [of underlying material] is completely transformed to calcite."
Show authors, comments, and common names
| Cephalopoda |
| Ammonitida - Placenticeratidae |
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| Ammonitida - Baculitidae |
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| Ammonitida - Scaphitidae |
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