USGS MR 4987, Alexander Avenue, Marin Headlands (M-2aE) (Jurassic of the United States)

Where: Marin County, California (37.8° N, 122.5° W: paleocoordinates 27.0° N, 57.7° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Pliensbachian (190.8 - 182.7 Ma)

• Assemblage MH-1: Pliensbachian (probably late) and (or) Toarcian. Only Pliensbachian, according to Kohnen & Murchey, 1995.

• bed-level stratigraphic resolution

Environment/lithology: basinal (siliceous); lithified chert

Size class: macrofossils

Reposited in the USGS

Primary reference: B. Murchey. 1984. Biostratigraphy and lithostratigraphy of chert in the Franciscan complex, Marin Headlands, California. Franciscan Geology of Northern California Field Trip Guidebook 43, Society of Economic Paleontologists and Mineralogists, Pacific Section 51-70 [M. Clapham/M. Clapham]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 185248: authorized by Matthew Clapham, entered by Matthew Clapham on 17.04.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

 Polycystina -
Nassellaria "indet. A" Ehrenberg 1875 radiolarian
 Nassellaria - Bagotidae
Canutus rockfishensis Pessagno and Whalen 1982 radiolarian
Bagotum aff. modestum Pessagno and Whalen 1982 radiolarian
 Nassellaria - Eucyrtidiidae
? Eucyrtidium "sp. B" Ehrenberg 1847 radiolarian
Stichocapsa "sp. A" Haeckel 1881 radiolarian
 Nassellaria - Foremanellinidae
Riedelius "sp. A" De Wever 1982 radiolarian
 Nassellaria - Parvicingulidae
Canoptum poissoni Pessagno et al. 1979 radiolarian
 Nassellaria - Syringocapsidae
Katroma aff. neagui Pessagno and Poisson 1981 radiolarian
 Spumellaria - Pantanelliidae
Pantanellium "sp. A" Pessagno 1977 radiolarian