Bahia Mazarredo - San Julian Fm (Miocene of Argentina)

Where: Argentina (47.0° S, 66.7° W: paleocoordinates 47.7° S, 60.3° W)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: San Julián Formation, Early/Lower Miocene (23.0 - 16.0 Ma)

• STRATIGRAPHIC RELATIONS: From beds of the San Julián Fm, which unconformably overlies the Deseado Fm and is overlain by the Early Miocene Monte Leon Fm. THICKNESS: From multiple beds within formation that reaches a thickness of 80 m. AGE: Late Oligocene-Early Miocene according to molluscan biostratigraphy. Assigned to the Early Miocene based on the the recognition of the JR assemblage. STRATIGRAPHIC POSITION: From uppermost parts of the formation.

• group of beds-level stratigraphic resolution

Environment/lithology: coastal; poorly lithified, sandy limestone

• ENVIRONMENT: Environmental data not reported in text. Siliciclastic shallow marine assemblage.
• SPECIFIC LITHOLOGY: Sandy limestone. LITHIFICATION: Poorly-lithified on the basis of figured specimes.

Size class: macrofossils

Collection methods: COLLECTOR: List includes both new collections by the author, and examination of museum and previously reported taxa. REPOSITORY: Museo Argentino de Ciencias Naturales Bernadino Rivadavia, Buenos Aires, Argentina.

Primary reference: C. J. del Rio. 2004. Tertiary Marine Molluscan Assemblages of Eastern Patagonia (Argentina): A Biostratigraphic Analysis. Journal of Paleontology 78(6):1097-1122 [L. Ivany/P. Wall/P. Wall]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 71403: authorized by Austin Hendy, entered by Austin Hendy on 24.04.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for bivalvia and gastropoda. NOMENCLATURE: Not an authoritaive publication, but providing revised generic placement for many previously reported antiquated names.
unclassified
  -
Gastropoda
 Trochoidea - Trochidae
 Trochoidea - Tegulidae
 Opisthobranchia -
 Cerithioidea - Turritellidae
"Turritella" ambulacrum Sowerby 1846 turret shell
 Neotaenioglossa - Trichotropidae
? Trichosirius patagonica Cossmann 1899 snail
 Epitonioidea - Epitoniidae
 Sorbeoconcha - Naticidae
""Polynices" secunda" = Polinices
""Polynices" secunda" = Polinices moon snail
 Neogastropoda - Nassariidae
 Neogastropoda - Mangeliidae
"Fusiguraleus pilsbry" = Neoguraleus (Fusiguraleus)
"Fusiguraleus pilsbry" = Neoguraleus (Fusiguraleus) snail
 Neogastropoda - Volutidae
"Lyria" dalli Ihering 1907 volute
 Neogastropoda - Muricidae
"Hadriania" jorgensis Ihering 1907 murex snail
Trophon santacrucensis Ihering 1897 murex snail
 Sorbeoconcha - Struthiolariidae
 Sorbeoconcha - Ranellidae
"Siphonalia nodosocincta" = Sassia armata
"Siphonalia nodosocincta" = Sassia armata Hupé 1854 triton shell
 Sorbeoconcha - Ficidae
Ficus carolina d'Orbigny 1847 fig shell
Bivalvia
 Nuculanida - Malletiidae
Neilo (Neilo) ornata Sowerby 1846 clam
 Mytilida - Crenellidae
 Mytilida - Mytilidae
"Aulacomya cf. ater" = Aulacomya atra, Modiolus ameghinoi
"Aulacomya cf. ater" = Aulacomya atra Molina 1782 mussel
Modiolus ameghinoi Ihering 1907 mussel
 Pectinida - Pectinoidae
"Swiftopecten iheringii" = Chlamys (Swiftopecten) iheringii del Rio 1995 scallop
Jorgechlamys centralis Sowerby 1846 scallop
"Zygochlamys geminatus" = Zygochlamys geminata Sowerby 1846 scallop
""Chlamys" jorgensis" = Chlamys (Zygochlamys) jorgensis Ihering 1907 scallop
 Pectinida - Limidae
"Lima (Limatula) pisum" = Limatula, "Lima (Limatula) cossmanni" = Limatula, Neoinoceramus ameghinoi, "Lima (Limaria) patagonia" = Limaria
"Lima (Limatula) pisum" = Limatula file clam
"Lima (Limatula) cossmanni" = Limatula file clam
"Lima (Limaria) patagonia" = Limaria file clam
 Pectinida - Anomiidae
 Ostreida - Pinnidae
Pinna (Atrina) magellanica Ihering 1907 oyster
 Ostreida - Ostreidae
Crassostrea hatcheri Ihering 1899 oyster
 Arcida - Parallelodontidae
"Cucullaea darwini" = Cucullaria darwini
"Cucullaea darwini" = Cucullaria darwini Philippi 1887 clam
 Arcida - Cucullaeidae
 Arcida - Limopsidae
Limopsis insolita Sowerby 1846 clam
 Cardiida - Veneridae
"Chione" patagonica Philippi 1887 venus clam
"Chione" eupyga Ihering 1907 venus clam
"Chione" casa Ihering 1907 venus clam
Dosinia meridonalis Ihering 1897 venus clam
Retrotapes scutata venus clam
Pitar julianum venus clam
 Pholadida - Corbulidae
 Lucinida - Lucinidae
 Carditida - Crassatellidae
 Carditida - Carditidae
"Fasciculicardia inaequalis" = Glyptoactis (Fasciculicardia) clam