UCMP 3689, east of Mount Diablo (Eocene of the United States)

Where: Contra Costa County, California (37.8° N, 121.6° W: paleocoordinates 40.5° N, 104.5° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Meganos Formation, Ypresian (56.0 - 47.8 Ma)

• "Meganos" faunas represent upper Bulitian and lower Penutian local ages=Ypresian

• bed-level stratigraphic resolution

Environment/lithology: coastal; lithified, fine-grained, pebbly, calcareous sandstone

• Shallow marine coastal siliciclastic environment
• Fine, micaceous sandstone, commonly with small pebbles, thinly beeded near bottom, more massive at top, yellow-brown to gray in color. The massive sandstones near top contain lenses of harded calcareous and fossiliferous sandstones.

Size class: macrofossils

Reposited in the UCMP

Collection methods: quarrying,

• Collected by Clark and Woodford. Collections reposited at UCMP.

Primary reference: B. L. Clark and A. O. Woodford. 1927. The geology and paleontology of the type section of the Meganos Formation (lower Middle Eocene) of California. University of California Publications in Geological Sciences 17(2):63-142 [A. Miller/A. Hendy/P. Wagner]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 52434: authorized by Austin Hendy, entered by Austin Hendy on 05.08.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

• Identified by Clark and Stewart.
Show authors, comments, and common names
Gastropoda
 Opisthobranchia - Cylichnidae
"Scaphander cf. costatus" = Scaphander (Mirascapha) costatus
"Scaphander cf. costatus" = Scaphander (Mirascapha) costatus Gabb 1864 snail
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium cooperi
Dentalium cooperi Gabb 1864 tusk shell
Bivalvia
 Nuculida - Nuculidae
"Nucila (Acila) gabbiana" = Acila (Truncacila) decisa
"Nucila (Acila) gabbiana" = Acila (Truncacila) decisa Conrad 1855 divaricate nutclam
 Nuculanida - Nuculanidae
"Leda gabbi" = Nuculana (Saccella) gabbii
"Leda gabbi" = Nuculana (Saccella) gabbii Conrad 1866 pointed nut clam
 Arcida - Arcidae
"Arca hornii" = Pachecoa hornii
"Arca hornii" = Pachecoa hornii Gabb 1864 clam
Subspecies: Arca hornii elusa
 Mytilida - Mytilidae
"Modiolus (Brachydontes) ornatus" = Brachidontes (Brachidontes) cowlitzensis
"Modiolus (Brachydontes) ornatus" = Brachidontes (Brachidontes) cowlitzensis Weaver and Palmer 1922 mussel
 Lucinida - Lucinidae
"Phacoides gyrata" = Gibbolucina (Eomiltha) gyrata
"Phacoides gyrata" = Gibbolucina (Eomiltha) gyrata Gabb 1864 clam
 Cardiida - Mactridae
"Spisula meganosensis n. sp." = Pseudocardium meganosensis
"Spisula meganosensis n. sp." = Pseudocardium meganosensis Clark and Woodford 1927 clam
 Cardiida - Veneridae
"Macrocallista meganosensis n. sp." = Microcallista (Costacallista) conradiana meganosensis
"Macrocallista meganosensis n. sp." = Microcallista (Costacallista) conradiana meganosensis Clark and Woodford 1927 venus clam