Alisitos Fm. (UCB A-8323) (Cretaceous of Mexico)

Where: Baja California, Mexico (31.5° N, 116.7° W: paleocoordinates 29.9° N, 68.2° W)

• small collection-level geographic resolution

When: upper Member (Alisitos Formation), Late/Upper Aptian (122.5 - 113.0 Ma)

• Age: "Aptian to middle Albian." Squires and Saul (2004) confirming and following Allison (1974) place this collection in the Late Aptian.

• bed-level stratigraphic resolution

Environment/lithology: shallow subtidal; limestone

• "Lowest caprinid limestone of Punta China section."

Collection methods: mechanical,

Primary reference: E. C. Allison. 1955. Middle Cretaceous gastropoda from Punta China, Baja California, Mexico. Journal of Paleontology 29(3):400-432 [J. Alroy/M. Sommers/J. Alroy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 1883: authorized by John Alroy, entered by Mike Sommers on 10.06.1999

Creative Commons license: CC BY (attribution)

Taxonomic list

• Abundances: A = 20+, C = 6-20, F = 3-5, R = 1-2. "A spectacular feature of the middle Albian deposits at Punta China is the fine preservation exhibited by many of the fossils. Despite the coarseness of some of the volcanic breccias, fragile tests of Forams, echinoids, and small molluscs are almost perfectly preserved. Pelecypods almost always occur with both valves intact. Some gastropods retain original pigmentation."
Show authors, comments, and common names
Bivalvia
 Hippuritida - Caprinuloideidae
Caprinuloidea sp.
Caprinuloidea sp. Palmer 1928 rudist
Gastropoda
 Heterostropha - Nerineidae
Nerinea (Plesioptygmatis) tomasensis
Nerinea (Plesioptygmatis) tomasensis Allison 1955 snail
(Plesioptygmatis) n. sp.