Where: Santa Cruz, Argentina (47.5° S, 71.9° W: paleocoordinates 48.2° S, 66.5° W)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Santa Cruz Formation, Santacrucian (17.5 - 16.3 Ma)

• Santacrucian age.

•The age of the SCF in Lago Posadas is based on six 40Ar/39Ar dates provided by Blisniuk et al.

•(2005), with an age span of 22-14 Ma. Based on regional tephrochronology and sedimentation rates estimations, Perkins et al. (2012) questioned the age for the lower strata of the SCF of Lago Posadas and concluded it should be close to 18 Ma. The latter was also supported by Cuitiño et al. (2015) based on Sr-stratigraphy for the underlying marine deposits, whose younger beds are chronologically located in 18 Ma. These age estimations provide an age span of roughly 4 my, from 18 Ma to 14 Ma, for the SFC in Lago Posadas. A note of caution has to be made related to the younger age (14.24±0.78 Ma) obtained by Blisniuk et al. (2005), since the stratigraphic position of this dated level corresponds to a tuff located 3 m beneath the top of the SCF in a place located 10 km southeast of the locality studied herein. That locality, shows thicker exposures of the SCF, which means that the dated level is probably not represented in the locality studied in this work and consequently the age of the top of our section should be somewhat older than 14.24±0.78 Ma.

• formation-level stratigraphic resolution

Environment/lithology: fluvial; lithified sandstone

Size class: macrofossils

Collected by Hatcher, Brown, Gonzalez-Ruiz in 1899, 1900, 1903, 2012

• Fossil vertebrates coming from the Santa Cruz formation in this area collected by the Princeton University expeditions are also catalogued as coming from “Lake Pueyrredon”

•

•Hatcher (1900, 1903) refers to the area of Lago Posadas, i.e., between the Río Furioso to the west, and Río Tarde to the east (Fig. 1), as “Lake Pueyrredon”.

•

•Hatcher went back to the area in 1899 with Barnum Brown from the American Museum of Natural History (AMNH, New York, USA). They stayed a longer period, making a larger collection of Santacrucian fossil vertebrates.

•

•Most of his collection is nowadays in the Yale Peabody Museum (YPM, New Haven, USA), and a few, mostly unprepared, specimens are in the AMNH. Since then, few paleontological expeditions visited the area, probably due to the difficulty for accessing these outcrops. There was a lack of effort in making a systematic collection of new fossils, excepting brief visits by a team from the Museo de La Plata (MLP, Argentina) in 1984, and a joint expedition of the Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB, Argentina) and the State University of New York at Stony Brook (SUNY, USA) in 2007 (González Ruiz, 2012).

Primary reference: J. I. Cuitiño, S. F. Vizcaíno, M. S. Bargo and I. Aramendía. 2019. Sedimentology and fossil vertebrates of the Santa Cruz formation (early Miocene) in Lago Posadas, southwestern Patagonia, Argentina. Andean Geology 46(2):383-420 [P. Mannion/M. Kouvari/M. Kouvari]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 210153: authorized by Philip Mannion, entered by Miranta Kouvari on 22.05.2020

Creative Commons license: CC BY (attribution)