Segundas Barrancas Blancas (SBB) - Estancia El Tordillo (EET) (Miocene of Argentina)

Where: Santa Cruz, Argentina (50.3° S, 70.2° W: paleocoordinates 50.9° S, 64.6° W)

• coordinate stated in text

• small collection-level geographic resolution

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

• Segundas Barrancas Blancas (SBB; 16.47–15.3 Ma), with three sites, Estancia Cordón Alto1 (ECA), Estancia Cordón Alto2 (ECA2), and Estancia el Tordillo (EET);

• formation-level stratigraphic resolution

Environment/lithology: "floodplain"; lenticular, paleosol/pedogenic, silty sandstone

• Floodplain deposits with paleosols, Sheet flood – crevasse splay deposits and Fluvial channel deposits
• The SCF here in the SBB is composed of fine-grained sediments of FAs 1 and 2, although conspicuous lenticular sandstone bodies of FA3 are observed (Fig. 10). The sections are locally correlated using a tuff layer (CECA-2 tuff; Cuitiño et al., 2016) and tabular, laterally extensive and distinctive yellow beds (Figs. 10 and 11). The CECA-2 tuff layer is about 1 m thick (Fig. 10.3) and was dated at the EET1 Section by Cuitiño et al. (2016) with an age of 16.32 ± 0.62 Ma. This tuff allows the correlation of Section EET1 with Section ECA1 (Fig. 11) 3.5 km away. Conspicuous yellow beds also used for correlation are a package of about 10 m of fine-grained sediments assigned to FA1 that contains two or three layers that contrast in color with the remaining beds of the SCF (Fig. 10). These beds were used to correlate sections EET2, ECA2 and ECA1 (Fig. 11). Although present in Section ECA, the yellow layers are barely visible due to the presence of thick lenticular sandstone deposits that partly erode them (Figs. 10.1 and 11). Finally, due to the lack of guide levels, Section Point 9 was located in the correlation scheme according to its elevation above sea level (Fig. 11).

Size classes: macrofossils, mesofossils

Collected by Fernicola et al in 2013-2014

• Recent fieldwork carried out between 2013 and 2014 by joint expeditions of the MLP, MACN, and Duke University

Primary reference: M. Arnal, M. G. Vucetich, D. A. Croft, M. S. Bargo, J. C. Fernícola and S. F. Viscaino. 2017. Systematic revision and evolutionary history of Acarechimys Patterson in Kraglievich 1965 (Rodentia, Caviomorpha, Octodontoidea). Ameghiniana 54(3):307-330 [P. Mannion/M. Kouvari]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 210637: authorized by Philip Mannion, entered by Miranta Kouvari on 10.06.2020

Creative Commons license: CC BY (attribution)

Taxonomic list

Mammalia
 Sparassodonta -
Sipalocyon gracilis2 Ameghino 1887 metatherian
 Paucituberculata - Palaeothentidae
Palaeothentes lemoinei2 Ameghino 1887 marsupial
Palaeothentes minutus2 Ameghino 1887 marsupial
 Astrapotheria - Astrapotheriidae
Astrapotherium sp.3 Burmeister 1879 placental
 Notoungulata - Interatheriidae
Interatherium sp.3, Protypotherium sp.3, Protypotherium australe3, "Protypotherium praerutilum" = Protypotherium praerutilum3, "Protypotherium attenuatum" = Protypotherium praerutilum3
Interatherium sp.3 Ameghino 1887 notoungulate
Protypotherium sp.3 Ameghino 1882 notoungulate
Protypotherium australe3 Moreno 1882 notoungulate
"Protypotherium praerutilum" = Protypotherium praerutilum3 Ameghino 1887 notoungulate
"Protypotherium attenuatum" = Protypotherium praerutilum3 Ameghino 1887 notoungulate
 Notoungulata - Hegetotheriidae
Pachyrukhos moyani3 Ameghino 1885 notoungulate
 Primates - Homunculidae
Homunculus vizcainoi4 Kay and Perry 2019 monkey
MPM-PV 19427, 8
 Rodentia -
Caviomorpha indet.1 caviomorph
 Rodentia - Neoepiblemidae
Perimys sp.1 Ameghino 1887 caviomorph
Perimys erutus1 Ameghino 1887 caviomorph
Perimys onustus1 Ameghino 1887 caviomorph
 Rodentia - Dinomyidae
cf. Scleromys sp.1 Ameghino 1887 caviomorph
 Rodentia -
Octodontoidea indet.1 Waterhouse 1839 caviomorph
Spaniomys sp.1 Ameghino 1877 caviomorph
 Rodentia - Octodontidae
Sciamys principalis1 Ameghino 1887 caviomorph
 Rodentia -
Acarechimys minutus Patterson and Pascual 1967 caviomorph
MPM-PV 15087 MPM-PV 15088 MPM-PV 17436 MPM-PV 17437
Acarechimys minutissimus Ameghino 1887 caviomorph
MPM-PV 17438
Acarechimys gracilis Ameghino 1891 caviomorph
MPM-PV 17439
Stichomys sp.1 Ameghino 1887 caviomorph
cf. Stichomys sp.1 Ameghino 1887 caviomorph
Stichomys/ Adelphomys
Stichomys regularis1 Ameghino 1887 caviomorph
Steiromys sp.1 Ameghino 1887 caviomorph
Neoreomys sp.1 Ameghino 1887 caviomorph
Neoreomys australis1 Ameghino 1887 caviomorph
cf. Eocardia sp.1 Ameghino 1887 caviomorph
Eocardia /Schistomys
Eocardia sp.1 Ameghino 1887 caviomorph
 Rodentia - Eocardiidae
Schistomys erro1 Ameghino 1887 caviomorph
 Rodentia - Chinchillidae
Prolagostomus sp.1 Ameghino 1887 chinchilid
cf. Prolagostomus sp.1 Ameghino 1887 chinchilid
Prolagostomus/Pliolagostomus
Pliolagostomus notatus1 Ameghino 1887 chinchilid
 Panameriungulata - Proterotheriidae
Anisolophus floweri5 Ameghino 1887 placental