Upper Member, Zorritos Formation (Miocene of Peru)

Where: Tumbes, Peru (3.7° S, 80.7° W: paleocoordinates 4.9° S, 76.4° W)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Upper Member (Zorritos Formation), Early/Lower Miocene (23.0 - 16.0 Ma)

• Stated as Early Miocene by Spieker (1922) and corroborated by more recent publications (e.g. see Higley 2004). Overlies the late Oligocene-early Miocene Heath Fm and underlies the Cardalitos Fm in Higley (2004) although Spieker (1922) uses varying lithostratigraphic nomenclature suggesting a "Talara Fm" overlies the upper member of the Zorritos Fm. Its is not clear whether definitions of these members has changed since Spieker. The upper member of the Zorritos Fm is 200 ft thick and comprises mostly conglomerates and sandstones.

• member-level stratigraphic resolution

Environment/lithology: coastal; poorly lithified, sandy conglomerate and poorly lithified, yellow, conglomeratic sandstone

• Shallow water, sandy littoral, agitated.
• Heavy conglomerates, sandstones, locally calcareous and fossiliferous locally loose and friable. Color prevailingly yellow.

Size class: macrofossils

Reposited in the YPM

• Collected by J. Singewald, and with inspection of collections by E.T. Nelson (1870) at Yale University. Possibly also involved inspection of Grzybowski's material (Geol. Inst. of Cracow). Singewald's material is presumably reposited at Johns Hopkins.

Primary reference: E. M. Spieker. 1922. The Paleontology of the Zorritos Formation of the North Peruvian Oil Fields. The Johns Hopkins University Studies in Geology 3:1-196 [A. Miller/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 58999: authorized by Austin Hendy, entered by Austin Hendy on 05.03.2006

Creative Commons license: CC BY (attribution)

Taxonomic list

• Probably not exhaustive though certainly representative of diversity of Mollusca for these units.
Bivalvia
 Arcida - Arcidae
"Arca (Scapharca) imporcata" = Anadara (Grandiarca) chiriquiensis, "Arca (Anadara) nelsoni" = Anadara (Grandiarca) chiriquiensis, "Arca (Scapharca) crescens" = Anadara (Grandiarca) chiriquiensis, "Arca (Scapharca) obesiformis" = Anadara (Grandiarca) chiriquiensis, "Arca (Anadara) septifera" = Anadara (Grandiarca) chiriquiensis, "Arca (Anadara) toroensis" = Anadara (Grandiarca) chiriquiensis
"Arca (Scapharca) imporcata" = Anadara (Grandiarca) chiriquiensis Gabb 1861 ark
"Arca (Anadara) nelsoni" = Anadara (Grandiarca) chiriquiensis Gabb 1861 ark
"Arca (Scapharca) crescens" = Anadara (Grandiarca) chiriquiensis Gabb 1861 ark
"Arca (Scapharca) obesiformis" = Anadara (Grandiarca) chiriquiensis Gabb 1861 ark
"Arca (Anadara) septifera" = Anadara (Grandiarca) chiriquiensis Gabb 1861 ark
"Arca (Anadara) toroensis" = Anadara (Grandiarca) chiriquiensis Gabb 1861 ark
Includes: A. (A.) toroensis crassa and A. (A.) toroensis prolata
 Pectinida - Pectinoidae
"Pecten woodringi" = Argopecten woodringi
"Pecten woodringi" = Argopecten woodringi Spieker 1922 calico scallop
 Pectinida - Anomiidae
"Anomia berryi" = Anomia (Anomia) peruviana
"Anomia berryi" = Anomia (Anomia) peruviana d'Orbigny 1846 jingle
 Pholadida - Corbulidae
"Corbula (Cuneocorbula) acutirostra" = Cuneocorbula
"Corbula (Cuneocorbula) acutirostra" = Cuneocorbula clam
 Cardiida - Anatinellidae
"Labiosa (Raeta) gabbi" = Raeta gabbi, "Labiosa (Raeta) gardnerae" = Raeta gardnerae
"Labiosa (Raeta) gabbi" = Raeta gabbi Pilsbry and Johnson 1917 clam
"Labiosa (Raeta) gardnerae" = Raeta gardnerae Spieker 1922 clam
 Cardiida - Veneridae
"Chione (Chione) angelana" = Chione (Chionopsis) angelana, "Chione (Chione) variabilis" = Chione (Chionopsis) variabilis, "Pitaria (Lamelliconcha) cora" = Lamelliconcha cora, "Clementia dariena" = Clementia (Clementia) dariena
"Chione (Chione) angelana" = Chione (Chionopsis) angelana Spieker 1922 venus clam
"Chione (Chione) variabilis" = Chione (Chionopsis) variabilis Nelson 1870 venus clam
"Pitaria (Lamelliconcha) cora" = Lamelliconcha cora Brown and Pilsbry 1911 venus clam
Subspecies: Pitaria (Lamelliconcha) cora aequicincta
"Clementia dariena" = Clementia (Clementia) dariena Conrad 1855 venus clam
 Cardiida - Tellinidae
"Tellina (Eurytellina) aequicincta" = Eurytellina aequicincta
"Tellina (Eurytellina) aequicincta" = Eurytellina aequicincta Spieker 1922 tellin clam
Gastropoda
 Neogastropoda - Conidae
Conus cacuminatus Spieker 1922 cone shell
Conus molis Brown and Pilsbry 1911 cone shell
Subspecies: Conus molis bravoi
 Sorbeoconcha - Potamididae
"Potamides ormei" = Potamides suprasulcatus
"Potamides ormei" = Potamides suprasulcatus Gabb 1873 horn snail
Subspecies: Potamides ormei infraliratus
 Sorbeoconcha - Turritellidae
Turritella robusta Grzybowski 1899 turret shell
"Turritella infracarinata" = Turritella (Turritella) infracarinata Grzybowski 1899 turret shell
Includes: Turritella infracarinata zorritoensis
Turritella inca Grzybowski 1899 turret shell
Subspecies: Turritella inca trita
Turritella filicincta Spieker 1922 turret shell
Subspecies: Turritella filicincta varicosta
Turritella nelsoni Spieker 1922 turret shell
Includes: Turritella nelsoni rotundata and T. nelsoni trullissatia
 Sorbeoconcha - Cerithiidae
Cerithium grillanum Spieker 1922 cerith snail
Cerithium infranodatum Spieker 1922 cerith snail