Also known as Zone of Chasichimys bonaerense
Where: La Pampa, Argentina (37.4° S, 65.5° W: paleocoordinates 37.6° S, 63.2° W)
• coordinate stated in text
• outcrop-level geographic resolution
When: Cerro Azul Formation, Huayquerian (8.0 - 5.0 Ma)
• Early late Miocene
•The stratotype is the lower level of the Cerro Azul Formation outcropping at this locality
•Montalvo et al. 2019: The revision of the vertebrate assemblage from this locality, as well as new geomorphologic and sedimentological interpretations of the Cerro Azul Formation in the area, confirms the previous assignation to the Chasicoan age.
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•Prevosti et al. 2023: Between 9 and ca. 7.7 Ma, there is a transitional fauna, represented by the assemblages retrieved from Cerro Patagua, Cerro La Bota, and Algarrobo del Águila, with taxa already recorded in the Chasicoan fauna and the appearance of four taxa ca. 8 Ma that reach at least 7.3 Ma. These are “Orthomyctera”, Proeuphractus limpidus, Macrochorobates scalabrinii, and Tetrastylus laevigatus, possibly representing the first instances of the beginning of the “Huayquerian” fauna. We did not consider Cerro La Bota as part of the Chasicoan fauna but as representative of a transition between the Chasicoan fauna and the “Huayquerian” fauna, together with Cerro Patagua and Algarrobo del Águila (cf. Contreras et al., 2013).
Environment/lithology: fluvial; lithified, massive, red, sandy siltstone and lithified, medium-grained, sandy conglomerate
•The amalgamated conglomeradic–sandy bodies suggest the episodic development of perennial streams without flow division on a loessic substrate.
•Schmidt et al. 2018: Levels of Cerro Azul formation at Cerro La Bota represent an ephemeral fluvial event (Goin et al. 2000; Verzi et al. 2008).
•Montalvo et al. 2019: The FA1 crops out in the lower part of the studied section and is 1.7 m thick (Fig. 2). It includes sheet-like strata with non-erosive bases, composed of massive and commonly very fine-grained siltstones (facies Fsm) with root traces (facies P).The FA2 is 2.2 m thick and overlays FA1 deposits with erosive contact (Fig. 2). It is constituted by a lateral and vertical erosive superposition of sandstone (facies St) and conglomeratic (facies Gt) bodies.
Size classes: macrofossils, mesofossils
Collection methods: Montalvo et al. 2019: specimens recovered belong to the Paleontological Collection of the Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa (La Pampa Province, Argentina).
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•Esteban, et al. 2000: Todos los ejemplares analizados están depositados en
•la Cátedra de Geología Histórica de la Facultad de Ciencias Exactas y Naturales de la Universidad Nacional ele La Pampa, Argentina, cuyo acrónimo es GHUNLPam
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 152063: authorized by Carlos Jaramillo, entered by Maria Vallejo on 05.11.2013, edited by Grace Varnham, Miranta Kouvari and Kateryn Pino
Creative Commons license: CC BY (attribution)
Taxonomic list
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| Reptilia | |
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| Mammalia | |
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Dasypodidae indet.4, Vetelia perforata4, Macrochorobates scalabrinii, Eutatini indet.4, Doellotatus inornatus4, Chasicotatus ameghinoi, Euphractini indet.4, Chorobates villosissimus4, Proeuphractus sp.4, Proeuphractus limpidus4, Zaedyus pichiy1
Macrochorobates scalabrinii Moreno and Mercerat 1891 armadillo
Chasicotatus ameghinoi Scillato-Yané 1977 armadillo | |
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Hemihegetotherium torresi7 Cabrera and Kraglievich 1931 notoungulate GHUNLPam 351, GHUNLPam 5303, GHUNLPam 5307, GHUNLPam 5307, GHUNLPam 6983, GHUNLPam 21975
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Caviidae indet.4, cf. Procardiomys indet.4, cf. Procardiomys sp.3, cf. Orthomyctera indet.4, cf. Orthomyctera sp.3
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Lagostomus telenkechanum2 Rasia and Candela 2017 viscacha GHUNLPam 5986 left mandible with i and p4-m3
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Octodontoidea indet.4, Octodontoidea "indet. 1"4, Octodontoidea "indet. 2"4, cf. Chasichimys indet.4, cf. Chasichimys sp.3, Chasichimys bonaerense
Chasichimys bonaerense Pascual 1967 caviomorph | |
Octodontidae indet.3, "Metacaremys primitiva" = Metacaremys primitiva3, "Cercomys primitiva" = Metacaremys primitiva4
"Metacaremys primitiva" = Metacaremys primitiva3 Piñero et al. 2021 caviomorph GHUNLPam 5969, 6922, 6925, 6926, 6927, 6928, 6929, 21984, 21986, 21987, 21989
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