UCMP 1173, Sobrante anticline (Oligocene of the United States)

Where: Contra Costa County, California (38.0° N, 122.2° W)

• Paleocoordinates: 42.5° N, 108.6° W (Wright 2013)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: San Ramon Formation, Chattian (28.1 - 23.0 Ma)

• Contains a fauna typical of the Agasoma gravidum beds. The ridge at this location contains the San Ramon Formation and Sobrante Formation, but only the San Ramon Formation contains the Agasoma gravidum beds. Formation generally assigned an upper Oligocene age (Hertlein & Grant, 1972; Amano, 1999), but could be Miocene.

• group of beds-level stratigraphic resolution

Environment/lithology: marine; poorly lithified siliciclastic sediments

Size class: macrofossils

Reposited in the UCMP

Primary reference: H. G. Schenck. 1931. Cephalopods of the genus Aturia from western North America. University of California Publications, Bulletin of the Department of Geological Sciences 19:435-490 [M. Clapham/K. Okamoto/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 180446: authorized by Matthew Clapham, entered by Matthew Clapham on 16.07.2016, edited by Jonathan Marcot

Creative Commons license: CC BY (attribution)

Taxonomic list

Gastropoda
 Sorbeoconcha - Ranellidae
"Bursa mathewsonii" = Mediargo mathewsoni
"Bursa mathewsonii" = Mediargo mathewsoni Gabb 1866 triton shell
p. 226
 Neogastropoda - Nassariidae
Molopophorus biplicatus Gabb 1866 snail
 Neogastropoda - Olividae
Olivella quadriplicata Clark 1918 olive snail
Bivalvia
 Cardiida - Veneridae
"Dosinia mathewsonii" = Dosinia (Dosinia) whitneyi
"Dosinia mathewsonii" = Dosinia (Dosinia) whitneyi Gabb 1866 venus clam
 Solenida - Solenidae
"Solen curtus" = Solena (Plectosolen) conradi, "Solen gravidus" = Solena (Plectosolen) gravidus
"Solen curtus" = Solena (Plectosolen) conradi Dall 1900 clam
"Solen gravidus" = Solena (Plectosolen) gravidus Clark 1918 clam
 Arcida - Glycymerididae
"Glycimeris tenuimbricata" = Glycymeris (Tucetona) tenuimbricata
"Glycimeris tenuimbricata" = Glycymeris (Tucetona) tenuimbricata Clark 1918 clam
p. 218
 Nuculida - Nuculidae
"Acila muta" = Acila (Truncacila) muta
"Acila muta" = Acila (Truncacila) muta Clark 1918 divaricate nutclam
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium radiolineata Clark 1918 tusk shell
type locality of ssp. Dentalium radiolineata sobrantensis
Cephalopoda
 Nautilida - Aturiidae
Aturia sp. Bronn 1838