Quebrada Gustavo section, Sierra de Villicúm (Ordovician of Argentina)

Also known as upper San Juan Fm., Gustavo Creek, Villicum Range

Where: San Juan, Argentina (31.2° S, 68.5° W: paleocoordinates 34.5° S, 133.2° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: San Juan Formation, Darriwilian (467.3 - 458.4 Ma)

• Eoplacognathus variabilis to E. suecicus zone, Middle Ordovician; both conodont zones correspond to the middle Darriwilian stage (see http://www.nhm.uio.no/norges/timescale/9b_Lower_Paleozoic_Sept08.pdf)

• member-level stratigraphic resolution

Environment/lithology: open shallow subtidal; argillaceous lime mudstone and shelly/skeletal wackestone

• "The San Juan Formation was deposited on an open carbonate shelf, and was bounded to the west by continental slope and oceanic basin deposits (Beresi, 1986). The diverse marine fauna and the lack of features indicative of restricted marine conditions suggest low-energy, subtidal conditions on an open platform during the entire interval of San Juan Formation deposition. The calcareous algae and cyanobacteria indicate deposition within the photic zone [...] "
• "argillaceous lime-mudstones, fossiliferous wackestones, K-bentonites, and calcarenites"

Size class: macrofossils

Preservation: cast

Collected by M. S. Beresi

• INGEO-PI = Invertebrate collections of Instituto de Geología, Facultad de Ciencias Exactas, Físicas y Naturales de la Universidad Nacional de San Juan

•PI-IANIGLA = Invertebrate collections of Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, Mendoza

Primary reference: B. Kröger, M. S. Beresi, and E. Landing. 2007. Early orthoceratoid cephalopods from the Argentine Precordillera (Lower-Middle Ordovician). Journal of Paleontology 81(6):1266-1283 [P. Wagner/P. Wagner/B. Kröger]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 87620: authorized by Björn Kröger, entered by Torsten Liebrecht on 21.03.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

Cephalopoda
 Orthocerida - Orthoceratidae
? Orthoceras sp. Breynius 1832
PI-IANIGLA No. 941 Vi70, No. 942 Vi73
 Orthocerida - Proteoceratidae
Gangshanoceras villicumense n. sp. Kröger et al. 2007
INGEO-PI No. 691 Vi82 (type) + possibly some of the 20 reported specimens in the PI-IANIGLA collections
 Orthocerida - Baltoceratidae
Cochlioceras sp. Eichwald 1860
INGEO-PI No. 686 Vi11