Computer Media (SDSNH 3278) (Eocene of the United States)

Also known as Poway, in part

Where: San Diego County, California (32.8° N, 117.1° W: paleocoordinates 33.5° N, 103.1° W)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Scripps Formation (La Jolla Group), Lutetian (47.8 - 41.3 Ma)

• From the lowermost part of the section. A single bed, 50-70 cm thick, approximately 11m below the Friars-Stadium contact. Magnetochron C21n (early Lutetian) at the Computer Media section, according to Walsh et al. (2005). The land-mammal assemblage from locality 3278 contains the insectivore Crypholestes?, a genus apparently endemic to

•southern California and only confidently identifed from strata of early Uintan "Age" (middle Eocene) (Novacek, 1976). The fossil assemblage from locality SDSNH 3278 contains molluscan taxa indicative of the middle Eocene "Transition Stage" of West Coast provincial molluscan biostratigraphy (Clark and Vokes, 1936; as refined by Givens and Kennedy, 1979). In terms of correlation with the standard European section, Givens (1974), Givens and Kennedy (1979), Saul (1983), and Squires (1984, 1987) considered the middle Eocene "Transition Stage" to be correlative with the middle part of the Lutetian Stage.

• bed-level stratigraphic resolution

Environment/lithology: shoreface; fine-grained, medium, shelly/skeletal, gray, conglomeratic sandstone

• The co-occurrence of both complete, delicate shells (e.g., the gastropods Diodora and Zachrysia) and abraded shells (e.g., the bivalves Barbatia and Corbicula) and the co occurrence of ecologically mixed (e.g. marine species and terrestrial species; sandy bottom species and rocky rubble species), as well as the lack of articulated bivalves, suggests post-mortem transportation of shell material to a common site of deposition (i.e., a storm-bed accumulation). Sand-rich/pebbly nature, mixture of terrestrial and marine components, and presence of plant-rich mudstone (probable lagoon) a few meters higher, suggest shoreface environment.
• Fine to medium sandstone, gray, fossiliferous, with basal cobble conglomerate. At the base of the fossiliferous bed is pebble conglomerate with fossils tightly packed in among the clasts as whole and fragmented shell material. The pebble conglomerate grades upward into a pebbly sandstone where shells are unoriented and "floating" in the matrix. The lower contact of the bed is undulatory and erosional, and the upper contact is gradational.

Size class: macrofossils

Preservation: original aragonite, original calcite

Collected by B.O. Riney in 1985

Primary reference: S. L. Walsh. 1991. Eocene mammal faunas of San Diego County. Pacific Section SEPM 68:161-178 [J. Alroy/J. Alroy/M. Uhen]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 16712: authorized by John Alroy, entered by John Alroy on 12.04.1997, edited by Mark Uhen and Patricia Holroyd

Creative Commons license: CC BY (attribution)

Taxonomic list

• originally assigned to Friars Fm.; see Walsh 1996b
at the base of the Computer Media section of Walsh et al. 1996
 Rotaliacea - Elphidiidae
 Arcida - Arcidae
Barbatia sp.3 Gray 1842 clam
 Arcida - Glycymerididae
"Glycymeris (Glycymeris) rosecanyonensis" = Glycymeris rosecanyonensis3, "Glycymeris (Glycymerita) sagittata" = Axinaea sagittata3
"Glycymeris (Glycymeris) rosecanyonensis" = Glycymeris rosecanyonensis3 Hanna 1927 clam
"Glycymeris (Glycymerita) sagittata" = Axinaea sagittata3 Gabb 1864 clam
 Ostreida - Flemingostreidae
Acutostrea idriaensis3 Gabb 1868 oyster
 Carditida - Carditidae
 Pholadida - Corbulidae
"Corbula (Carycorbula) dickersoni" = Corbula dickersoni3
"Corbula (Carycorbula) dickersoni" = Corbula dickersoni3 Weaver and Palmer 1922 clam
 Cardiida - Corbiculidae
 Cardiida - Mactridae
""Spisula" bisculpturata" = Mactromeris bisculpturata3
""Spisula" bisculpturata" = Mactromeris bisculpturata3 Anderson and Hanna 1942 clam
 Cardiida - Veneridae
"Callista (Costacallista) soledadensis" = Costacallista3, Tivela (Pachydesma) weaveri3
"Callista (Costacallista) soledadensis" = Costacallista3 venus clam
 Cardiida - Donacidae
? Donax sp.3 Linnaeus 1758 clam
 Cardiida - Tellinidae
"Tellina castacana" = Tellina (Angulus) castacana3 Anderson and Hanna 1925 tellin clam
Tellina aff. townsendsis3 tellin clam
n. sp.
Tellina soledadensis3 Hanna 1927 tellin clam
"Tellina lebecki" = Tellina (Phyllodina) lebecki3 Anderson and Hanna 1925 tellin clam
 Solenida - Solenidae
Solena (Eosolen) novacularis3 Anderson and Hanna 1925 clam
 Nuculida - Nuculidae
Acila (Truncacila) decisa3 Conrad 1855 divaricate nutclam
 Protobranchia - Nuculanidae
"Nuculana (Saccella) aff. gabbi" = Saccella3
"Nuculana (Saccella) aff. gabbi" = Saccella3 pointed nut clam
 Opisthobranchia - Cylichnidae
"Scaphander (Mirascapaha) costatus" = Scaphander costatus3
"Scaphander (Mirascapaha) costatus" = Scaphander costatus3 Gabb 1864 snail
 Architaenioglossa - Ampullinidae
Eocernina hannibali3 Dickerson 1914 snail
Pachycrommium clarki3 Stewart 1927 snail
 Neogastropoda - Olividae
Olivella mathewsonii3 Gabb 1864 olive snail
 Ficoidea - Ficidae
Ficopsis remondii3 Gabb 1864 fig shell
subspecies crescentensis
 Naticoidea - Naticidae
Sinum obliquum3, "Neverita (Neverita) globosa" = Neverita globosa3
Sinum obliquum3 Gabb 1864 moon snail
"Neverita (Neverita) globosa" = Neverita globosa3 Gabb 1868 moon snail
 Calyptraeoidea - Calyptraeidae
Calyptraea diegoana3 Conrad 1855 slipper shell
 Rissooidea - Vitrinellidae
 Sorbeoconcha - Thiaridae
Loxotrema turritum3 Gabb 1868 snail
? Thiara sp.3 Röding 1798 snail
 Sorbeoconcha - Turritellidae
Turritella buwaldana3 Dickerson 1916 turret shell
 Sorbeoconcha - Pleuroceridae
 Pulmonata - Camaenidae
Zachrysia fraterna n. sp.2 Roth 1988 land snail
 Neritoidea - Neritidae
 Fissurelloidea - Fissurellidae
 Dentaliida - Dentaliidae
Dentalium sp.3 Linnaeus 1758 tusk shell
 Nautilida - Aturiidae
Aturia sp.3 Bronn 1838 nautiloid
 Carchariniformes - Triakidae
cf. Galeorhinus sp.3 de Blainville and Prévost 1816 school shark
 Siluriformes - Ariidae
Ariidae indet.3 Berg 1958 Ariid catfish
 Crocodylia -
cf. Tomistoma sp.3 Müller 1846 false gharial
 Loricata -
Pristichampsus sp.3 Gervais 1853 crocodilian
 Macroscelidea - Amphilemuridae
? Crypholestes sp. Novacek 1980 elephant shrew
? Crypholestes sp.3 Novacek 1980 elephant shrew
 Theriiformes - Herpetotheriidae
Peratherium sp.3 Aymard 1850 marsupial
 Didelphimorphia - Didelphidae
Didelphidae indet.1 Gray 1821 opossum
Labyrinthus ? sp.2 Kobluk 1979
 Scleractinia - Turbinoliidae
Turbinolia pusillanima3 Nomland 1916 stony coral