Along Corral Creek, Milne Ranch, southwest Muddy Mountain: Spathian, Wyoming
collected 1983
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
|
Reptilia
- Eosauropterygia
|
|||||||
|
Corosaurus alcovensis
Case 1936
|
1 specimen | ||||||
| see common names | |||||||
Geography
| Country: | United States | State/province: | Wyoming |
| Coordinates: | 42.6° North, 106.3° West (view map) | ||
| Paleocoordinates: | 10.3° North, 31.8° West | ||
| Basis of coordinate: | estimated from map | ||
| Geographic resolution: | small collection |
Time
| Period: | Triassic | Epoch: | Early/Lower Triassic |
| Stage: | Olenekian | 10 m.y. bin: | Triassic 1 |
| Key time interval: | Spathian | ||
| Age range of interval: | 248.90000 - 247.20000 m.y. ago |
Stratigraphy
| Geological group: | Chugwater | Formation: | Crow Mountain | Member: | Alcova Limestone |
| Stratigraphy comments: Alcova (Limestone) Member, Crow Mountain Formation, Chugwater Group
The stratigraphic correlation and hence determination of the relative geological age of the Alcova Limestone is rendered difficult by the general paucity of fossils, vertebrates (Corosaurus) and invertebrates alike (for a review see Storrs, 1991). The presence of the nothosauriform reptile Corosaurus has led some workers (Colbert, 1957; Zangerl, 1963) to assign the Alcova to the Upper Triassic. Storrs (1991:101) accepted a late Lower Triassic (Scythian, Spathian) or, perhaps, an early Middle Triassic (Anisian) age for the Alcova Limestone | |||||
Lithology and environment
| Primary lithology: | dolomitic,stromatolitic,shelly/skeletal,gray lithified silty,carbonaceous "limestone" |
| Includes fossils? | Y |
| Lithology description: The Alcova is a very hard, dense, resistant, microsparitic limestone in beds approximately 2-25 cm thick...The limestone is microlaminated, slightly fossiliferous, and locally dolomitic. Clastic content is generally low but vriable; quartz silt particles are locally common, increasingly so near pinchout boundaries. This silt is good evidence for natural lateral termination in these areas. Carbonate-pebble conglomerate is occasionally present in the unit. The Alcova limestone is usually grey in color, but can exhibit mottling of pink, red, yellow, and brown as a result of staining by ferric iron (hematite). Algal stromatolites are abundant in the lower portion of the unit...The limestone is ubiquituously petroliferous but is particularly high in organic content in the Alcova area where the rock is dark grey in color... The horizontal-to-wavy algal laminations of the Alcova are the principal bedding structures of the unit. | |
| Environment: | shallow subtidal indet. |
Taphonomy
| Modes of preservation: | body |
| Size of fossils: | macrofossils |
Collection methods and comments
| Collection methods: | surface (float),field collection |
| Reason for describing collection: | taxonomic analysis |
| Museum repositories: | YPM | Collection dates: | 1983 |
| Collection method comments: Most of the Yale Peabody Museum specimens were discovered in talus blocks beneath cliffs of the horizontal Alcova Limestone | |
Metadata
| Database number: | 138081 | ||
| Authorizer: | R. Benson | Enterer: | R. Benson |
| Modifier: | R. Benson | Research group: | vertebrate |
| Created: | 2013-01-04 20:36:23 | Last modified: | 2013-05-14 08:50:37 |
| Access level: | the public | Released: | 2013-01-04 20:36:23 |
| Creative Commons license: | CC BY |
Reference information
Primary reference:
| 46813. | G. W. Storrs. 1991. Anatomy and relationships of Corosaurus alcovensis (Diapsida: Sauropterygia) and the Triassic Alcova Limestone of Wyoming. Bulletin of the Peabody Museum of Natural History 44:1-151 [R. Benson/R. Benson] |
Secondary references:
| 28997 | O. Rieppel. 1998. Corosaurus alcovensis Case and the phylogenetic interrelationships of Triassic stem-group Sauropterygia. Zoological Journal of the Linnean Society 124:1-41 [S. Peters/D. Lovelace] |