Alisitos Fm. (UCB A-8319): Late/Upper Aptian, Mexico

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Bivalvia - Trigoniida - Trigoniidae
Trigonia stolleyi Hill 1893
r category
Bivalvia - Arcida - Cucullaeidae
Cucullaea sp. Lamarck 1801
r category
see common names

Geography
Country:Mexico State/province:Baja California
Coordinates: 31.5° North, 116.7° West (view map)
Paleocoordinates:29.9° North, 68.2° West
Geographic resolution:small collection
Time
Period:Cretaceous Epoch:Early/Lower Cretaceous
10 m.y. bin:Cretaceous 2-3
*International age/stage:Aptian - Albian
Key time interval:Late/Upper Aptian
Age range of interval:119.50000 - 113.00000 m.y. ago
* legacy (obsolete) database fields
Stratigraphy
Formation:Alisitos Member:upper
Stratigraphic resolution:bed
Stratigraphy comments: Age: "Aptian to middle Albian." Squires and Saul (2004) confirming and following Allison (1974) place this collection in the Late Aptian.
Lithology and environment
Primary lithology: sandstone
Environment:shallow subtidal indet.
Geology comments: "Blue tuffaceous sandstone containing large pelecypods and bundles of serpulid worm tubes. ~2 m strat. below A-8318."
Taphonomy
Modes of preservation:body
Collection methods and comments
Collection methods:mechanical,field collection
Reason for describing collection:taxonomic analysis
Taxonomic list comments:CONTAINS SERPULID WORM TUBES. 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."
Metadata
Database number:1880
Authorizer:J. Alroy Enterer:M. Sommers
Modifier:A. Hendy Research group:marine invertebrate
Created:1999-06-10 15:36:54 Last modified:2006-09-08 17:32:17
Access level:the public Released:1999-06-10 15:36:54
Creative Commons license:CC BY
Reference information

Primary reference:

51. 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]

Secondary references:

18606 R. L. Squires and L. R. Saul. 2004. Uncommon Cretaceous naticiform gastropods from the Pacific Slope of North America. The Velliger 47(1-2):21-37 [A. Miller/A. Hendy]