USGS 13750 - Tamaulipas, Mexico (Yegua Formation): Middle Eocene, Mexico
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
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Gastropoda
- Ampullinidae
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Gastropoda
- Neogastropoda
- Buccinidae
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Pseudoliva ? vetusta
(Conrad 1833)
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| see common names | |||||||
Geography
| Country: | Mexico | State/province: | Tamaulipas |
| Coordinates: | 26.4° North, 99.2° West (view map) | ||
| Paleocoordinates: | 32.2° North, 82.0° West (Wright 2013) | ||
| Basis of coordinate: | based on nearby landmark | ||
| Geographic resolution: | outcrop |
Time
| Period: | Paleogene | Epoch: | Eocene |
| 10 m.y. bin: | Cenozoic 2-3 | ||
| Key time interval: | Middle Eocene | ||
| Age range of interval: | 48.07 - 37.71 m.y. ago |
Stratigraphy
| Geological group: | Claiborne | Formation: | Yegua | ||
| Local section: | Rancho El Quitrin | ||||
| Regional section: | Tamaulipas | ||||
| Stratigraphic resolution: | bed | ||||
| Stratigraphy comments: The succession of Claiborne Group in northeastern Mexico is exceptionally thick and well correlated to those units of the same name in Texas on the basis of faunal similarity. The Yegua Formation is the highest formation of the Claiborne Group and has a thickness of around 1500 m. For the most part the Yegua Formation in non-marine. The lower Yegua Formation is 60 m thick and comprises about 60 ft of basal shale, clay, sand, and oyster beds and about 100 m of scarp-making sandstone, this sequence is again repeated above. Collection is contained in a dark-gray sandy clay a little above the top of the lignite, which lies about 100 m above the base of the formation. | |||||
Lithology and environment
| Primary lithology: | gray sandy "shale" |
| Includes fossils? | Y |
| Lithology description: Dark-gray sandy clay. | |
| Environment: | marginal marine indet. |
| Geology comments: Siliciclastic, and probably brackish. | |
Taphonomy
| Modes of preservation: | permineralized,replaced with silica |
| Size of fossils: | macrofossils |
Collection methods and comments
| Collection methods: | selective quarrying,field collection |
| Reason for describing collection: | taxonomic analysis |
| Museum repositories: | USNM |
| Collection method comments: Collections reposited in USGS and USNM collections. | |
| Taxonomic list comments:Exhaustive for mollusca. | |
Metadata
| Also known as: | USGS 13750 | ||
| Database number: | 43044 | ||
| Authorizer: | A. Hendy | Enterer: | A. Hendy |
| Modifier: | A. Hendy | Research group: | marine invertebrate |
| Created: | 2004-08-09 13:01:41 | Last modified: | 2025-02-22 15:12:02 |
| Access level: | the public | Released: | 2004-08-09 13:01:41 |
| Creative Commons license: | CC0 | ||
Reference information
Primary reference:
| 7474. | J. Gardner. 1945. Mollusca of the Tertiary formations of Northeastern Mexico. Geological Society of American Memoir 11 [M. Kosnik/M. Kosnik/M. Kosnik] |