CSUN Loc. 1563, Larch Mountain area, Black Hills (Eocene of the United States)

Also known as LACMIP Loc. 16655; LACMIP loc. 41563

Where: Thurston County, Washington (48.0° N, 123.1° W: paleocoordinates 51.9° N, 103.4° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: CP10-11 nannofossil zone, Crescent Formation, Ypresian (56.0 - 47.8 Ma)

• Middle early Eocene age ("Capay Stage"), upper part of the Crescent Formation. ore recent information suggests that the “Capay” stage is Early Eocene with an age of ~50.5 to 53 Ma B.P. (e.g., Squires, 1997). Given as CP 9-11 in Squires 1997, so the upper part would be CP10-11.

• group of beds-level stratigraphic resolution

Environment/lithology: sand shoal; silty mudstone

• Extrusion of the basalt caused shoaling and the establishment of a rocky shoreline community where gastropod and bivalved mollusks lived with colonial corals and abundant coralline algae. Shells were transported a short distance seaward where they were deposited as a matrix of coquina that infilled spaces between basalt boulders. Many of the shells in the coquina are small to minute, and their size prevented them from being destroyed during transport. Within the coquina are a few larger shells, like those of the new species, that apparently lived in the shallowsubtidal environment where coquina accumulation took place (Squires & Goedert, 1994; in press).
• Fossil-bearing rocks at both localities consist of a thin section of richly fossiliferous and conglomeratic silty mudstone interbedded with basalt.

Size classes: macrofossils, mesofossils

Reposited in the LACM

Primary reference: L. T. Groves and R. L. Squires. 1995. First Report of the Genus Proadusta Sacco, 1894 (Gastropoda: Cypraeidae) from the Western Hemisphere, with a Description of a New Species from the Eocene of Washington. The Nautilus 109(4):113-116 [P. Wagner/P. Wagner]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 176361: authorized by Pete Wagner, entered by Pete Wagner on 09.02.2016, edited by Mihaela Krause, Mark Uhen, Jonathan Marcot and Barbara Seuss

Creative Commons license: CC BY (attribution)

Taxonomic list

Polychaeta
 Serpulimorpha -
Gastropoda
 Heterostropha - Orbitestellidae
Orbitestella palaiopacifica n. sp.8 Squires and Goedert 1996 snail
 Heterobranchia - Omalogyridae
Ammonicera benhami n. sp.8 Squires and Goedert 1996 snail
 Lepetellida - Scissurellidae
Scissurella (Scissurella) malloryi n. sp.8 Squires and Goedert 1996 snail
 Lepetellida - Fissurellidae
Puncturella (Altrix) pacifica n. sp.8 Squires and Goedert 1996 snail
 Trochoidea - Turbinidae
Arene olympiata n. sp.8 snail
 Neritoidea - Neritidae
Nerita (Bajanenta) larix n. sp.7 Saul and Squires 1997 snail
 Sorbeoconcha - Caecidae
Caecum benhami n. sp.2 snail
Caecum sp.2 Fleming 1813 snail
 Neogastropoda - Costellariidae
Conomitra capitolina n. sp.8 Squires and Goedert 1996 ribbed mitre
 Sorbeoconcha - Pediculariidae
Cypraeogemmula warnerae9 Effinger 1938 snail
 Sorbeoconcha - Eratoidae
Eratotrivia crescentensis4 Weaver and Palmer 1922 snail
 Sorbeoconcha - Cypraeidae
Bernaya grovesi4, "Proadusta goedertorum n. sp." = Subepona goedertorum
Bernaya grovesi4 Squires and Demetrion 1992 cowry
"Proadusta goedertorum n. sp." = Subepona goedertorum Groves and Squires 1995 cowry
 Sorbeoconcha - Eocypraeidae
"Eocypraea (Eocypraea) crescentensis n. sp." = Eocypraea crescentensis3
"Eocypraea (Eocypraea) crescentensis n. sp." = Eocypraea crescentensis3 Groves 2011 snail
Polyplacophora
 Neoloricata - Ischnochitonidae
Lepidochitona squiresi1 Dell'Angelo et al. 2011 chiton
Thecostraca
 Verrucomorpha - Verrucidae
Verruca sp.6 Schumacher 1817 barnacle