Also known as Zone of Xenodontomys simpsoni

Where: La Pampa, Argentina (36.7° S, 64.2° W: paleocoordinates 36.8° S, 62.5° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Cerro Azul Formation, Messinian (7.2 - 5.3 Ma)

• The stratotype is recognized in the lower levels of the Cerro Azul Formation in this locality

•This zone is also recognized in the lower levels of the Cerro Azul Formation at El Guanaco (368 170 S–648 160 W

•

•Romano et al. 2023: Biochronological methods were useful in ordering and estimating the age of the different faunas of the Cerro Azul Formation, ranging from ca. 8 to ca. 5.7 Ma. Some appear to be transitional between Chasicoan and “Huayquerian” faunas (Cerro La Bota, Cerro Patagua, and Algarrobo del Águila), and other three (Barrancas Coloradas, El Guanaco, and Caleufú) cover the latest Miocene, even some of them could have reached the earliest Pliocene.

•

•La Pampa Province. But the chronomorph of X. simpsoni recorded in El Guanaco is slightly more derived, suggesting that these bearing levels are younger than those

•outcropping at Barrancas Coloradas (Verzi et al., 2004a, 2004b).

•

•Sostillo et al 2018: The Cerro Azul Formation deposits (Linares et al., 1980) are discontinuous along the whole occupied area in the provinces of La Pampa and Buenos Aires (Fig. 2). They are composed of silts, sandy silts and very thin silty sands, reddish and brown colored, with a homogeneous and com- pact general aspect, and frequent carbonate nodules and evidences of pedogenic processes (Folguera and Zárate, 2009). Visconti et al. (2010) interpreted them as eolian deposits characterized by loessic materials, with a high per- centage of lithic fragments and volcaniclastic sediments. Detailed geological and stratigraphic descriptions of the Cerro Azul Formation are provided by Linares et al. (1980), Goin et al. (2000), Visconti et al. (2010), and Folguera and Zárate (2009).

Environment/lithology: terrestrial; massive, red, sandy siltstone

Size classes: macrofossils, mesofossils

Primary reference: D. H. Verzi, C. I. Montalvo, and C. M. Deschamps. 2008. Biostratigraphy and biochronology of the Late Miocene of central Argentina: Evidence from rodents and taphonomy. Geobios 41:145-155 [C. Jaramillo/M. Vallejo]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 152067: authorized by Carlos Jaramillo, entered by Maria Vallejo on 05.11.2013, edited by Juan Carrillo, Miranta Kouvari, Philip Mannion and Kateryn Pino

Creative Commons license: CC BY (attribution)