USGS 13600 - Nuevo Leon, Mexico (lower Laredo Formation) (Eocene of Mexico)

Also known as USGS 13600

Where: Nuevo Leon, Mexico (26.7° N, 99.2° W: paleocoordinates 28.7° N, 89.7° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Lower Member (Laredo Formation), Middle Eocene (47.8 - 37.7 Ma)

• 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 name Laredo Formation replaces the "Cook Mountain Formation" in the Rio Grande embayment. The Laredo Formation is divided into three members: lower, middle and upper. The collection is from the lower member.

• bed-level stratigraphic resolution

Environment/lithology: marine; shale

• Siliciclastic. No paleoenvironmental data reported.
• No concise lithological description of the lower Laredo Formation, although several collections are described similarly as coming from shales with associated limestones and concretionary horizons.

Size class: macrofossils

Reposited in the USNM

Collection methods: quarrying,

• Collections reposited in USGS and USNM collections.

Primary reference: J. Gardner. 1945. Mollusca of the Tertiary formations of Northeastern Mexico. Geological Society of American Memoir 11 [M. Kosnik/M. Kosnik/M. Kosnik]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 42994: authorized by Austin Hendy, entered by Austin Hendy on 07.08.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for mollusca.
Gastropoda
 Cerithioidea - Turritellidae
Turritella nasuta turret shell
 Sorbeoconcha - Naticidae
Neverita limula Conrad 1833 moon snail
Subspecies: Neverita limula ceryx
 Neogastropoda - Fasciolariidae
 Neogastropoda - Volutidae
"Volutospina ? clayi" = Athleta (Volutospina)
"Volutospina ? clayi" = Athleta (Volutospina) volute
Bivalvia
 Pholadida - Corbulidae
Corbula (Caricorbula) carli, "Corbula (Varicorbula) smithvillensis" = Vokesula smithvillensis
"Corbula (Varicorbula) smithvillensis" = Vokesula smithvillensis Harris 1919 clam
 Arcida - Arcidae
Halonanus ? pulchrus Gabb 1860 clam