Alisitos Fm. (UCB A-8314) (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; conglomerate

• "Dark volcanic breccia containing a few large molluscs, underlying A-8313."

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 1875: 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
 Ostreida - Gryphaeidae
Exogyra yabei
Exogyra yabei Nagao 1934 oyster
 Ostreida - Ostreidae
"Ostrea carinata" = Rastellum carinatum
"Ostrea carinata" = Rastellum carinatum Lamarck 1806 oyster
(Arctostrea)
Gastropoda
 Heterostropha - Acteonellidae
Actaeonella fusiformis
Actaeonella fusiformis Coquand 1865 snail
quest. ident. - originally entered as "Acteonella fusiformis"
 Heterostropha - Nerineidae
Nerinea (Plesioptygmatis) tomasensis
Nerinea (Plesioptygmatis) tomasensis Allison 1955 snail
(Plesioptygmatis) n. sp.