USGS 13985 - Tamaulipas, Mexico (middle Laredo Formation) (Eocene of Mexico)

Also known as USGS 13985

Where: Tamaulipas, Mexico (26.4° N, 99.2° W: paleocoordinates 28.4° N, 89.6° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Middle 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 middle member.

• bed-level stratigraphic resolution

Environment/lithology: marine; glauconitic, brown, gray, calcareous sandstone

• Siliciclastic. No paleoenvironmental data reported.
• Matrix is characteristically a brownish-gray, calcareous, glauconitic sandstone interbedded in buff sandstone and shale.

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 42983: authorized by Austin Hendy, entered by Austin Hendy on 07.08.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for mollusca.
Gastropoda
 Neogastropoda - Volutidae
"Volutospina lapparoides" = Athleta (Volutospina)
"Volutospina lapparoides" = Athleta (Volutospina) volute
 Sorbeoconcha - Naticidae
Neverita limula Conrad 1833 moon snail
Subspecies: Neverita limula ceryx
 Heterostropha - Architectonicidae
"Architectonica alveata" = Architectonica (Stellaxis) alveatum
"Architectonica alveata" = Architectonica (Stellaxis) alveatum Conrad 1833 sundial