CSUN Loc. 458, Chivo Canyon (Eocene of the United States)

Where: Ventura County, California (34.3° N, 118.7° W: paleocoordinates 35.1° N, 104.6° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Llajas Formation, Lutetian (47.8 - 41.3 Ma)

• The stewart bed is a 1 m thick sandstone unit in the middle of the Llajas formation. Lutetian, chron 21r according to Squires (2001).

• bed-level stratigraphic resolution

Environment/lithology: transition zone or lower shoreface; lithified, bioturbated sandstone

• The "Stewart bed" is located in a section of transition from shallow-marine to outer slope and shelf facies. A nearshore environment is interpreted for that portion of the shallow-marine (transgressive) facies which consists of laminated beds alternating with bioturbated beds. In such cases, the finely laminated sand represents storm-influenced stratification, and the biogenic reworking is the inter-storm activity. Shell fragments commonly are concentrated as channel lags in surge channels. Fossils were apparently subjected to wave action because the apices of elongate shells such as Turritella are bimodally oriented in opposite directions. The deeper the water, the less amount of laminated sandstone and the more amount of bioturbated sandstone. Such areas, which were farther below effective wave base, existed 1) where the shallow-marine (transgressive) facies grades into the outer shelf to slope facies and 2) in the shallow-marine (regressive) facies. One of the deepest-water shallow-marine beds was the "Stewart bed."
• sandstone.

Size class: macrofossils

Reposited in the LACM

Collection methods: bulk,

• Repository: Formerly California State University Northridge (CSUN)

Primary reference: R. L. Squires. 1983. New Mollusks from the Lower Middle Eocene Llajas Formation, Southern California. Journal of Paleontology 57(2):354-362 [L. Ivany/E. Kowalski/J. Marcot]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 8015: authorized by Linda Ivany, entered by Elizabeth Kowalski on 12.06.2000, edited by Matthew Clapham and Jonathan Marcot

Creative Commons license: CC BY (attribution)

Taxonomic list

Bivalvia
 Ostreida - Flemingostreidae
"Ostrea idriaensis" = Acutostrea idriaensis
"Ostrea idriaensis" = Acutostrea idriaensis Gabb 1869 oyster
 Ostreida - Pinnidae
Pinna llajasensis Squires 1983 oyster
 Carditida - Crassatellidae
Crassatella uvasana Conrad 1855 clam
 Carditida - Carditidae
Venericardia (Pacificor) hornii Gabb 1864 clam
as Venericardia (Pacificor) hornii calafia
 Cardiida - Cardiidae
"Nemocardium linteum" = Nemocardium (Nemocardium) linteum
"Nemocardium linteum" = Nemocardium (Nemocardium) linteum Conrad 1855 cockle
 Solenida - Solenidae
"Solena (Eosolen) navacularis" = Solena (Eosolen) novacularis
"Solena (Eosolen) navacularis" = Solena (Eosolen) novacularis Anderson and Hanna 1925 clam
Gastropoda
 Architaenioglossa - Ampullinidae
Eocernina hannibali Dickerson 1914 snail
 Stromboidea - Strombidae
"Ectinochilus (Macilentos) macilentus" = Ectinochilus (Macilentos) macilenta
"Ectinochilus (Macilentos) macilentus" = Ectinochilus (Macilentos) macilenta White 1889 true conch
 Xenophoroidea - Xenophoridae
Xenophora stocki Dickerson 1916 carrier shell
 Tonnoidea - Cassidae
"Galeodea (Caliagaleodea) californica" = Galeodea californica, "Phalium (Semicassis) tuberculiformis" = Morio (Sconsia) tuberculatus
"Galeodea (Caliagaleodea) californica" = Galeodea californica Clark 1942 snail
"Phalium (Semicassis) tuberculiformis" = Morio (Sconsia) tuberculatus Squires 1984 snail
Cephalopoda
 Nautilida - Aturiidae
Aturia myrlae Hanna 1927 nautiloid
Echinoidea
 Spatangoida - Schizasteridae
Schizaster diabloensis Kew 1920 heart urchin
Anthozoa
 Scleractinia - Montlivaltiidae
"? Trochocyathus striatus" = Trochosmilia striata
"? Trochocyathus striatus" = Trochosmilia striata Gabb 1864 stony coral
Bullaea
  -
"Megistostoma gabbianum" = Bullaea gabbiana
"Megistostoma gabbianum" = Bullaea gabbiana Stoliczka 1868