SDA-2:Molluskan Limy Sandstone (Triassic of Mexico)

Where: Sonora, Mexico (30.7° N, 112.6° W: paleocoordinates 11.6° N, 53.9° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Antimonio Formation, Late/Upper Triassic (237.0 - 201.3 Ma)

• The strata of the Monos and Antimonio Formations at Sierra del Alamo represents a nearly complete succession of marine sedimentary rock that ranges from Late Permian to Early Jurassic age.

• group of beds-level stratigraphic resolution

Environment/lithology: offshore shelf; lithified, calcareous sandstone

• Fine- to medium-grained sand thickens and thins laterally from 0.40 to 1 m . In thin sections this lithofacies is composed of poorly sorted, fine- to course-grained angular quartz grains in a calcite matrix. No sedimentary structures were evident in this lithology. Bedding may have been obliterated by burrowing bivalves or unpreserved soft-bodied organims. Disarticulated bivalve shells are common in the upper portion of limy sandstone beds.

Size class: macrofossils

Primary reference: D. H. Goodwin. 1999. Paleontology, Paleoecology, and Depositional Environments Within the Upper Triassic (Norian) Carbonate Strata of the Antimonio Formation, Northwest Sonora, Mexico. University of Montana [D. Bottjer/N. Bonuso/N. Bonuso]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 41020: authorized by David Bottjer, entered by Nicole Bonuso on 05.07.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

Bivalvia
 Ostreida - Gryphaeidae
Gryphaea sp. Lamarck 1801 oyster
 Ostreida - Bakevelliidae
Gervillaria sp. Cox 1951 oyster
 Cardiida - Palaeocarditidae
 Cardiida - Cardiidae
Septocardia sp. Hall 1877 cockle
 Trigoniida - Trigoniidae
Myophorigonia jaworskii Steinmann 1929 clam