PBDB Collection

Estación Boeuf (Neogene of Argentina)

Where: La Pampa, Argentina (36.0° S, 64.4° W: paleocoordinates 36.1° S, 62.2° W)

• coordinate stated in text

• small collection-level geographic resolution

When: Cerro Azul Formation, Huayquerian (8.0 - 5.0 Ma)

• The Cerro Azul Formation crops out in most of La Pampa Province, except in the southern region (Linares et al., 1980). It is a continental, nearly flat-lying unit composed of massive, pale red to pinkish siltstones and fine-grained sandstones with interbedded, poorly developed palaeosols (e.g., Linares et al., 1980; Goin et al., 2000). This lithostratigraphic unit is considered the distal portion of a clastic wedge related to the late Cenozoic Andean fold and thrust belt that is well developed in the neighbouring Mendoza Province. The maximum outcropping thickness is about 40 m, although the exposures are generally less than 5 m thick. The Cerro Azul Formation has yielded numerous vertebrate remains, specially mammals, which are referred to the Huayquerian land mammal age, which is of late Miocene age (Pascual and Bondesio, 1982; Montalvo and Casadío, 1988; Goin et al., 2000; Verzi et al., 1991, 1994, 1995, 1999, 2003, 2004; Montalvo et al., 1995, 1996, 1998; Esteban et al., 2001; Cerdeño and Montalvo, 2001, 2002). The base of the Cerro Azul Formation is covered and its top is overlain by Pliocene and younger (mostly aeolian) sediments or is composed of a discontinuous calcrete crust that forms a resistant layer responsible for the preservation from erosion of the unit. In the subsurface, the unit reaches ~370 m thick overlying older Cenozoic sediments or basement rocks (De Elorriaga and Tullio, 1998).

•Schmidt et al. 2018: Figure 2 illustrates the stratigraphic distribution of the locality giving a general age estimate of 7.2-7.5Ma

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•Romano et al. 2023: The presented 40Ar/39Ar “escoria” age estimate for Telén (average of 7.09 Ma) is contained in the older range of our previous inference.

• group of beds-level stratigraphic resolution

Environment/lithology: "floodplain"; lithified, paleosol/pedogenic, brown, gray, calcareous siltstone and lithified, fine-grained sandstone

• The recovered fauna, notoungulates and rodents specially, is indicative of steppes or herbaceous plains. Particularly, the hegetotheriid Paedotherium minor (Notoungulata) was a typical dweller of these environments in dry to humid warm climates (Bond et al., 1995), very abundant in this region during the late Miocene (Zetti, 1972; Cerdeño and Bond, 1998; Montalvo, 2004).

•Schmidt et al. 2018: Deposits at Telen, Bajo Giuliani, El Guanaco and Caleufú were interpreted as loess-like deposits with immature palaeosols and little diagenetic alteration

• The lithology of the section is monotonous, and mostly composed of carbonate-cemented greyish orange pink (5 YR 7/2) siltstones and fine-grained sandstones. The distinction of horizons in the soil profiles is poor and the stacked palaeosols are 1.7 m (lower) and 1.9 m (upper) thick. Both palaeosols are separated by a 2 to 7 cm thick, discontinuous bed of laminated, greyish-pink mudstone with mudcracks. Beneath the lower palaeosol lies a 0.5 m thick interval with poor pedogenic modification, which is a siltstone with abundant glass shards and no carbonate cementation. Each palaeosol exhibits a 1.2 to 1.4 m thick interval with greater carbonate cementation that is considered as a calcic horizon. The upper soil profile shows a second uppermost horizon, 0.30 m thick, more clayey than the rest of de soil, with fine prismatic peds and Celliforma isp. (fossil bee cell). Most conspicuous features of both palaeosols include pervasive (although not uniform) carbonate (micritic calcite) cementation, pedogenic slickensides and clastic dykes. Carbonate cementation is not homogeneous in the section. Calcium carbonate content is minimum (~1%) in the lower part of each palaeosol, increasing upward (~10%). At the field, carbonate cement appears as calcareous concretions with dominantly sub-vertical arrangement (up to 15 cm long and 5 cm diameter) and scarce nodules (1 to 2 cm in diameter). Pedogenic slickensides constitute curved, striated, clayey surfaces with a circular roughly concentric arrangement in plan view and a conical 3D pattern. These structures are 0.2 to 0.7 m in diameter and 1 m deep. Clastic dykes are 1 to 7 cm thick, sub-vertical, and filled by two to four pairs of symmetrical muddy laminae showing subtle lithology and colour contrasts. The classic dykes show no preferred orientation.

Size classes: macrofossils, mesofossils

• MACN-Pv 10050, right hemimandible without dentition inserted and the left hemimandible with c, root of p1, p2-m2

Collection methods: surface (in situ),

Primary reference: D. Hontecillas, L. H. Soibelzon, C. I. Montalvo and R. A. Bonini. 2023. Cyonasua zettii sp. nov. (Procyonidae, Mammalia) from the Late Miocene of Central Argentina and a review of the fossil record of Cerro Azul Formation. Historical Biology [E. Vlachos/F. Aspromonte/P. Mannion]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 232689: authorized by Evangelos Vlachos, entered by Franco Aspromonte on 21.12.2023

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names

Mammalia
Carnivora - Procyonidae	Cyonasua longirostris, Cyonasua zettii n. sp. Cyonasua longirostris Rovereto 1914 procyonid carnivore MACN-Pv 10050, right hemimandible without dentition inserted and the left hemimandible with c, root of p1, p2-m2 Cyonasua zettii n. sp. Hontecillas et al. 2023 procyonid carnivore MACN-Pv 6229 (holotype)