CSUN Loc. 374, 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)

• 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 CSUN (California State University Northridge)

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 8012: authorized by Linda Ivany, entered by Elizabeth Kowalski on 12.06.2000, edited by Austin Hendy, Matthew Clapham and Jonathan Marcot

Creative Commons license: CC BY (attribution)

Taxonomic list

Rhynchonellata
 Terebratulida - Terebrataliidae
Terebratalia aff. batequia3 Sandy et al. 1995
Polychaeta
 Sabellida - Serpulidae
Bivalvia
 Arcida - Glycymerididae
"Glycymeris (Glycymerita) sagittata" = Glycymeris sagittata2
"Glycymeris (Glycymerita) sagittata" = Glycymeris sagittata2 Gabb 1864 clam
 Pectinida - Pectinoidae
Spondylus carlosensis2 Anderson 1905 scallop
 Ostreida - Gryphaeidae
Pycnodonte (Phygraea) cf. pacifica3 Squires and Demetrion 1990 oyster
 Ostreida - Flemingostreidae
"Ostrea idriaensis" = Acutostrea idriaensis2
"Ostrea idriaensis" = Acutostrea idriaensis2 Gabb 1869 oyster
 Ostreida - Pteriidae
"Nayadina (Exputens) llajasensis" = Exputens llajasensis2
"Nayadina (Exputens) llajasensis" = Exputens llajasensis2 Clark 1934 pearl oyster
 Ostreida - Pinnidae
Pinna llajasensis n. sp. Squires 1983 oyster
 Mytilida - Mytilidae
Brachidontes (Brachidontes) cowlitzensis2 Weaver and Palmer 1922 mussel
 Carditida - Crassatellidae
Crassatella uvasana2 Conrad 1855 clam
 Carditida - Carditidae
Venericardia (Pacificor) hornii2 Gabb 1864 clam
as Venericardia (Pacificor) hornii calafia
 Pholadida - Teredinidae
? Teredo sp.2 Linnaeus 1758 clam
 Cardiida - Veneridae
"Marcia (Mercimonia) bunkeri" = Dosinia bunkeri2, Pitar (Calpitaria) uvasanus2, "Pitar uvasana" = Meretrix uvasana3
"Marcia (Mercimonia) bunkeri" = Dosinia bunkeri2 Hanna 1927 venus clam
"Pitar uvasana" = Meretrix uvasana3 Conrad 1855 venus clam
Subspecies: Pitar uvasana coquillensis
 Cardiida - Psammobiidae
"Gari texta" = Gari (Gobraeus) texta3 Gabb 1864 clam
Gari cf. eoundulata2 Vokes 1939 clam
 Cardiida - Cardiidae
"Nemocardium linteum" = Nemocardium (Nemocardium) linteum2, "Acanthocardia (Agnocardia) sorrentoensis" = Acanthocardia (Agnocardia) sorrentoense3, Acanthocardia (Schedocardia) brewerii2
"Nemocardium linteum" = Nemocardium (Nemocardium) linteum2 Conrad 1855 cockle
"Acanthocardia (Agnocardia) sorrentoensis" = Acanthocardia (Agnocardia) sorrentoense3 Hanna 1927 cockle
 Solenida - Solenidae
"Solena (Eosolen) navacularis" = Solena (Eosolen) novacularis2
"Solena (Eosolen) navacularis" = Solena (Eosolen) novacularis2 Anderson and Hanna 1925 clam
 Lucinida - Lucinidae
"Claibornites diegoensis" = Claibornites (Claibornites) diegoensis2
"Claibornites diegoensis" = Claibornites (Claibornites) diegoensis2 Dickerson 1916 clam
Gastropoda
 Ptenoglossa - Epitoniidae
Cirsotrema sp.2 Mörch 1852 wentletrap
 Opisthobranchia - Cylichnidae
"Cylichnina tantilla" = Cylichnella tantilla2
"Cylichnina tantilla" = Cylichnella tantilla2 Anderson and Hanna 1925 snail
 Tectibranchia - Akeridae
Akera maga3 Vokes 1939 snail
 Architaenioglossa - Ampullinidae
Eocernina hannibali2 Dickerson 1914 snail
Pachycrommium clarki2 Stewart 1927 snail
 Neogastropoda - Buccinidae
Ancistrolepis carolineae n. sp.2 Squires 1984 true whelk
 Neogastropoda - Melongenidae
"Ficopsis cooperiana" = Fusus (Hemifusus) cooperii2
"Ficopsis cooperiana" = Fusus (Hemifusus) cooperii2 Gabb 1864 snail
 Neogastropoda - Fasciolariidae
Clavilithes "n. sp. B"2, "Fusinus teglandae" = Fusinus teglandi2, "Clavilithes tabulatus" = Clavella tabulata2
Clavilithes "n. sp. B"2 Swainson 1840 snail
"Fusinus teglandae" = Fusinus teglandi2 Hanna 1927 snail
"Clavilithes tabulatus" = Clavella tabulata2 Dickerson 1913 snail
 Neogastropoda - Volutidae
Lapparia eomagna3 Vokes 1939 volute
 Neogastropoda - Tudiclidae
Pseudoperissolax blakei2 Conrad 1855 snail
as Pseudoperissolax blakei praeblakei
 Neogastropoda - Harpidae
"Eocithara mutica" = Harpa mutica2
"Eocithara mutica" = Harpa mutica2 Lamarck 1803 snail
as Eocithara mutica californiensis
 Neogastropoda - Turridae
? Cochlespiropsis jenkinsi n. sp.3, "Fusiturricula (Crenaturricula) crenatospira" = Crenaturricula crenatospira2, Surculites mathewsonii2
? Cochlespiropsis jenkinsi n. sp.3 Squires 2001 turrid
"Fusiturricula (Crenaturricula) crenatospira" = Crenaturricula crenatospira2 Cooper 1894 turrid
also as Fusiturricula (Crenaturricula) crenatospira domenginica
Surculites mathewsonii2 Gabb 1864 turrid
 Neogastropoda - Conidae
Conus hornii2 Gabb 1864 cone shell
as Conus hornii umpquaensis
 Stromboidea - Strombidae
"Ectinochilus (Macilentos) macilentus" = Ectinochilus (Macilentos) macilenta2
"Ectinochilus (Macilentos) macilentus" = Ectinochilus (Macilentos) macilenta2 White 1889 true conch
 Ficoidea - Ficidae
Ficopsis remondii2 Gabb 1864 fig shell
as Ficopsis remondii crescentensis
 Naticoidea - Naticidae
Polinices (Euspira) nuciformis2 Gabb 1864 moon snail
 Cypraeoidea - Cypraeidae
Cypraea castacensis2 Stewart 1927 cowry
 Xenophoroidea - Xenophoridae
Xenophora stocki2 Dickerson 1916 carrier shell
 Tonnoidea - Ranellidae
Cymatium janetae n. sp. Squires 1983 triton shell
Cymatium (Septa) janetae2 Squires 1983 triton shell
Ranella katherineae n. sp. Squires 1983 triton shell
"Olequahia domenginica" = Ranella domenginica2 Vokes 1939 triton shell
 Tonnoidea - Cassidae
"Galeodea (Caliagaleodea) californica" = Galeodea californica2, "Phalium (Semicassis) tuberculiformis" = Morio (Sconsia) tuberculatus2
"Galeodea (Caliagaleodea) californica" = Galeodea californica2 Clark 1942 snail
"Phalium (Semicassis) tuberculiformis" = Morio (Sconsia) tuberculatus2 Squires 1984 snail
 Sorbeoconcha - Turritellidae
Turritella andersoni2 Dickerson 1916 turret shell
as Turritella andersoni lawsoni
Turritella uvasana2 Conrad 1865 turret shell
as Turritella uvasana applinae
 Sorbeoconcha - Brachytrematidae
Benoistia umpquaensis2 Turner 1938 snail
 Architectonicoidea - Architectonicidae
"Architectonica (Stellaxis) cognata" = Stellaxis cognata2
"Architectonica (Stellaxis) cognata" = Stellaxis cognata2 Gabb 1864 sundial
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium stentor2 Anderson and Hanna 1925 tusk shell
Cephalopoda
 Nautilida - Aturiidae
Aturia myrlae2 Hanna 1927 nautiloid
 Nautilida - Nautilidae
Kummelonautilus sp.3 Matsumoto 1984 nautiloid
Chondrichthyes
 Lamniformes - Odontaspididae
Odontaspis sp.2 Agassiz 1843 sand tiger shark
 Galeomorphi -
Striatolamia macrota3 Agassiz 1843 shark
Echinoidea
 Spatangoida - Schizasteridae
Schizaster diabloensis2 Kew 1920 heart urchin
 Spatangoida - Brissidae
Eupatagus stevensi n. sp.1 Grant and Hertlein 1938 heart urchin
Anthozoa
 Scleractinia - Montlivaltiidae
"? Trochocyathus striatus" = Trochosmilia striata2
"? Trochocyathus striatus" = Trochosmilia striata2 Gabb 1864 stony coral
 Scleractinia - Oculinidae
"Archohelia clarki" = Petrophyllia clarki3
"Archohelia clarki" = Petrophyllia clarki3 Vaughan 1927 stony coral
Orthophragmina
  -
"Pseudophragmina (Proporocyclina) clarki" = Orthophragmina clarki2
"Pseudophragmina (Proporocyclina) clarki" = Orthophragmina clarki2 Cushman 1920
Bullaea
  -
"Megistostoma gabbianum" = Bullaea gabbiana2
"Megistostoma gabbianum" = Bullaea gabbiana2 Stoliczka 1868
Lyrischapa lajollaensis
  -
"Lyrischapa lajollaensis" = Pejona lajollaensis2
"Lyrischapa lajollaensis" = Pejona lajollaensis2 Hanna 1927