Barda Negra 2 (Miocene of Argentina)

Also known as BN2

Where: Neuquén, Argentina (39.0° S, 69.7° W: paleocoordinates 39.8° S, 64.2° W)

• coordinate stated in text

• small collection-level geographic resolution

When: Cerro Bandera Formation, Colhuehuapian (21.0 - 17.5 Ma)

• the fossil-bearing deposits of the Cerro Bandera Formation correlate with the Lower Faunal Zone in the Colhue Huapi Member of the Sarmiento Formation at Gran Barranca (south of Colhue Huapi Lake, central Patagonia), dated at 21.1–20.1 Ma (Dunn et al., 2013), the type section for the Colhuehuapian South American Land Mammal Age (SALMA).

•nearly 25 m from the exposed base.

• group of beds-level stratigraphic resolution

Environment/lithology: fluvial; paleosol/pedogenic, bentonitic, tuffaceous volcaniclastic sediments

• These outcrops represent the relicts of an old alluvial in-filling developed in small local valleys eroded into Late Cretaceous and Paleocene rocks (Leanza and Hugo, 1997;Kramarz et al., 2005).

•whitish-greyish tuffaceous horizons, about six meters from the base of the stratigraphic sec- tion exposed in the area (similar rocks as BN1) located nearly 25 m from the exposed base.

• The Cerro Bandera Formation is 45 m-thick and consists

•of pyroclastic deposits showing evidence of fluvial rework- ing and/or pedogenesis, alternating with primary fall-out pyroclastic deposits, with abundant bentonitic horizons in the lower section and scant intercalated sandstones in the upper section. The abundant tuffaceous and tuffitic con- tents would have originated from discontinuous ash fall derived from Andean or sub-Andean volcanic centers. The origin of these deposits is associated with a fluvial environ- ment in an intermontane foreland basin; lacustrine deposits accumulated in the central, topographically lower areas of the paleovalleys, whereas paleosols accumulated in the marginal, higher areas. This depositional system resulted in marked lateral facies variations among the currently isolated exposures (Leanza and Hugo, 1997; Kramarz et al., 2005)

Size classes: macrofossils, mesofossils

Collected in 2015; reposited in the MACN, MLP

Primary reference: A. G. Kramarz, M. Bond, and M. Arnal. 2015. Systematic description of three new mammals (Notoungulata and Rodentia) from the Early Miocene Cerro Bandera Formation, Northern Patagonia, Argentina. Ameghiniana 52(6):585-597 [P. Mannion/M. Kouvari]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 197284: authorized by Philip Mannion, entered by Miranta Kouvari on 31.10.2018

Creative Commons license: CC BY (attribution)

Taxonomic list

Mammalia
 Rodentia - Neoepiblemidae
Doryperimys olsacheri Kramarz et al. 2015 caviomorph
 Notoungulata - Interatheriidae
"Protypotherium sinclairi" = Protypotherium columnifer
"Protypotherium sinclairi" = Protypotherium columnifer Fernández et al. 2021 notoungulate