Alcatraz Island, recreation ground: Cenomanian, California
collected 1976

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Bivalvia - Myalinida - Inoceramidae
Buchia pacifica Jeletsky 1965
    = Inoceramus gradilis Pergament 1966
Elder and Miller 1993
Bivalvia - Pholadida - Pleuromyidae
Pleuromya sp. (Meek 1873)
original and current combination Myacites (Pleuromya)
see common names

Geography
Country:United States State/province:California County:San Francisco
Coordinates: 37.8° North, 122.4° West (view map)
Paleocoordinates:37.8° North, 82.6° West
Basis of coordinate:estimated from map
Geographic resolution:outcrop
Time
Period:Cretaceous Epoch:Late/Upper Cretaceous
Stage:Cenomanian 10 m.y. bin:Cretaceous 5
Key time interval:Cenomanian
Age range of interval:100.50000 - 93.90000 m.y. ago
Stratigraphy
Stratigraphic resolution:bed
Stratigraphy comments: Valanginian age initially based on Buchia pacifica. According to Elder & Miller, 1993: Unfortunately, these specimens appear to have been lost, and recent investigation of their locality yielded no fossils (C. Wahrhaftig, oral commun., 1992). This locality is less than two hundred feet stratigraphically below the new inoceramid locality in an apparently continuous graywacke sequence (C. Wahrhaftig, oral commun., 1992). It seems unlikely that a Valanginian to Cenomanian age span would be condensed within such a stratigraphically short graywacke interval. This leads us to speculate that the crushed specimens illustrated by Armstrong and Gallagher (1977) might actually be the middle Cenomanian inoceramid, Inoceramus gradilis Pergament, which looks very similar to Buchia pacifica.
Lithology and environment
Primary lithology: lithified sandstone
Environment:submarine fan
Taphonomy
Modes of preservation:mold/impression
Size of fossils:macrofossils
Collection methods and comments
Reason for describing collection:general faunal/floral analysis
Collection dates:1976
Collection method comments: Repository: not stated
Metadata
Database number:185239
Authorizer:M. Clapham Enterer:M. Clapham
Modifier:M. Clapham Research group:marine invertebrate
Created:2017-04-17 20:49:54 Last modified:2017-04-17 21:07:17
Access level:the public Released:2017-04-17 20:49:54
Creative Commons license:CC BY
Reference information

Primary reference:
62140. C. F. Armstrong and K. Gallagher. 1977. Fossils from the Franciscan assemblage, Alcatraz Island. California Geology 30(6):134-135 [M. Clapham/M. Clapham]

Secondary references:

62141 W. P. Elder and J. W. Miller. 1993. Map and checklists of Jurassic and Cretaceous macrofossil localities within the San Jose 1:100,000 Quadrangle, California, and discussion of paleontological results. United States Geological Survey Open-File Report 93-503:1-49 [M. Clapham/M. Clapham]