CSUN Loc. 444, Las Llajas Canyon (Eocene of the United States)

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

• 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; 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 8013: authorized by Linda Ivany, entered by Elizabeth Kowalski on 12.06.2000, edited by Austin Hendy and Jonathan Marcot

Creative Commons license: CC BY (attribution)

Taxonomic list

Polychaeta
 Sabellida - Serpulidae
Bivalvia
 Arcida - Glycymerididae
"Glycymeris (Glycymerita) sagittata" = Glycymeris sagittata1
"Glycymeris (Glycymerita) sagittata" = Glycymeris sagittata1 Gabb 1864 clam
 Pectinida - Pectinoidae
Spondylus carlosensis1 Anderson 1905 scallop
 Ostreida - Flemingostreidae
"Ostrea idriaensis" = Acutostrea idriaensis1
"Ostrea idriaensis" = Acutostrea idriaensis1 Gabb 1869 oyster
 Carditida - Crassatellidae
Crassatella uvasana1 Conrad 1855 clam
 Pholadida - Teredinidae
? Teredo sp.1 Linnaeus 1758 clam
 Cardiida - Cardiidae
"Nemocardium linteum" = Nemocardium (Nemocardium) linteum1
"Nemocardium linteum" = Nemocardium (Nemocardium) linteum1 Conrad 1855 cockle
 Solenida - Solenidae
"Solena (Eosolen) navacularis" = Solena (Eosolen) novacularis1
"Solena (Eosolen) navacularis" = Solena (Eosolen) novacularis1 Anderson and Hanna 1925 clam
Gastropoda
 Architaenioglossa - Ampullinidae
Eocernina hannibali1 Dickerson 1914 snail
Pachycrommium clarki1 Stewart 1927 snail
 Neogastropoda - Fasciolariidae
Clavilithes sp. n. sp. Swainson 1840 snail
 Neogastropoda - Turridae
"Fusiturricula (Crenaturricula) crenatospira" = Crenaturricula crenatospira1, Surculites mathewsonii1
"Fusiturricula (Crenaturricula) crenatospira" = Crenaturricula crenatospira1 Cooper 1894 turrid
as Fusiturricula (Crenaturricula) crenatospira domenginica
Surculites mathewsonii1 Gabb 1864 turrid
 Stromboidea - Strombidae
"Ectinochilus (Macilentos) macilentus" = Ectinochilus (Macilentos) macilenta1
"Ectinochilus (Macilentos) macilentus" = Ectinochilus (Macilentos) macilenta1 White 1889 true conch
 Cypraeoidea - Cypraeidae
Cypraea castacensis1 Stewart 1927 cowry
 Xenophoroidea - Xenophoridae
Xenophora stocki1 Dickerson 1916 carrier shell
 Tonnoidea - Ranellidae
Cymatium janetae n. sp., "Olequahia domenginica" = Ranella domenginica1
Cymatium janetae n. sp. Squires 1983 triton shell
"Olequahia domenginica" = Ranella domenginica1 Vokes 1939 triton shell
 Tonnoidea - Cassidae
"Galeodea (Caliagaleodea) californica" = Galeodea californica1, "Phalium (Semicassis) tuberculiformis" = Morio (Sconsia) tuberculatus1
"Galeodea (Caliagaleodea) californica" = Galeodea californica1 Clark 1942 snail
"Phalium (Semicassis) tuberculiformis" = Morio (Sconsia) tuberculatus1 Squires 1984 snail
 Sorbeoconcha - Turritellidae
Turritella andersoni1 Dickerson 1916 turret shell
as Turritella andersoni lawsoni
Turritella uvasana1 Conrad 1865 turret shell
as Turritella uvasana applinae
 Architectonicoidea - Architectonicidae
"Architectonica (Stellaxis) cognata" = Stellaxis cognata1
"Architectonica (Stellaxis) cognata" = Stellaxis cognata1 Gabb 1864 sundial
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium stentor1 Anderson and Hanna 1925 tusk shell
Cephalopoda
 Nautilida - Nautilidae
Kummelonautilus sp.2 Matsumoto 1984 nautiloid
Anthozoa
 Scleractinia - Montlivaltiidae
"? Trochocyathus striatus" = Trochosmilia striata1
"? Trochocyathus striatus" = Trochosmilia striata1 Gabb 1864 stony coral
Lyrischapa lajollaensis
  -
"Lyrischapa lajollaensis" = Pejona lajollaensis1
"Lyrischapa lajollaensis" = Pejona lajollaensis1 Hanna 1927