New Early Eocene Mammalian Fauna from Western Patagonia, Argentina

Abstract

Two new fossil mammal localities from the Paleogene of central-western Patagonia are preliminarily described as the basis for a new possible biochronological unit for the early Eocene of Patagonia, correlated as being between two conventional SALMAs, the Riochican (older) and the Vacan subage of the Casamayoran SALMA. The mammal-bearing strata belong to the Middle Chubut River Volcanic-Pyroclastic Complex (northwestern Chubut Province, Argentina), of

Patagonian Eocene Archaeopithecidae Ameghino, 1897 (Notoungulata): systematic revision, phylogeny and biostratigraphy

“…This variation was also mentioned by Simpson (1967b) for the teeth sample referred to Acropithecus rigidus (see above). This statement is crucial because the presence of a mesial cingulum was one of the characteristics alluded to by Tejedor et al (2009) for assigning their material to Archaeopithecus rogeri.…”

“…nov. in Gran Hondonada (Chubut Province), a locality referred to the Mustersan SALMA (late Eocene); however, the authors did not provide either a catalogue number or a figure of these specimens. Tejedor et al (2009) referred to Archaeopithecus cf. A. rogeri some maxillary and mandibular remains and isolated teeth from the Paso del Sapo fauna (late early Eocene, Woodburne et al, 2014a) represented in La Barda and Laguna Fría localities (west of Chubut Province).…”

“…In the case of Acropithecus remains from the Las Violetas fauna, these were recovered from outcrops, uncomformably overlying the Las Violetas Formation (Gelfo et al, 2010), assigned to Las Flores Formation (Río Chico Group), and referred to early Eocene (Bauzá et al, 2016). In turn, the presence of Archaeopithecus in the fauna from Paso del Sapo (Tejedor et al, 2009) is not discarded, bearing in mind that the Paso del Sapo fauna fills the gap between the Riochican SALMA and Vacan subage (Woodbourne et al, 2014b; but see Krause et al, 2017); however, the taxonomic affinities of these remains need to be corroborated. Finally, if the record of Archaeopithecus in the Mustersan levels of Gran Hondonada (Cladera et al, 2004) is confirmed, it would imply the youngest record and the biochronological extension of this taxon.…”

Evolução dos Toxodontia da América do Sul durante o Cenozoico: aspectos dentários, paleoclimáticos e paleoambientais

“…Nesta época, surgiram na Patagônia argentina, os primeiros notoungulados typotérios hipsodontes de tamanho médio, equivalentes a um cervo atual (Acropithecus no Riochiquense e Eohyrax no Vaquense) (Reguero & Prevosti 2010, Woodburne et al 2014. No entanto, em certas áreas restritas do interior da Patagônia teriam prevalecido condições mais quentes e secas, a julgar pelo registro paleoflorístico de anacardiáce-as (Barreda & Palazzesi 2007 (Tejedor et al 2009), idade correspondente ao final do OCEI (Fig. 3).…”

“…3). Os toxodontes da Patagônia argentina registrados durante o OCEM (Vaquense-Barranquense) são Anisotemnus, Pleurostylodon e Thomashuxleya, isotemnídeos braquiodontes com dentição similar a Isotemnus do Riochiquense, embora já exibam uma coroa mais elevada, bem como o notohippídeo Plexotemnus (Simpson 1967, Tejedor et al 2009, López et al 2010, Woodburne et al 2014.…”