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Among the great diversity of Oligocene mammals from Quebrada Fiera (Mendoza Province, Argentina), three families of typotherian notoungulates are very abundant. Since the first paper on archaeohyracids in 2010 until the last fieldwork in 2016, numerous unpublished remains were added to the collection. The study of all these remains, together with some revised materials, allows us to provide new anatomical data and some taxonomic decisions on these groups. Within Hegetotheriidae, we present one of the most complete skulls of "Prohegetotherium schiaffinoi" known to date, providing descriptions of certain previously unknown features of the caudal cranium; MCNAM-PV 3984 is discarded as belonging to Hegetotheriopsis sulcatus, as recently suggested, and is considered as Hegetotheriinae indet., like other isolated large specimens and some teeth previously determined as Prohegetotherium sp.; and several well-preserved specimens add to the sample of the pachyrukhine Prosotherium garzoni, including a partial maxilla with erupting P2. Concerning "Archaeohyracidae", Archaeohyrax suniensis is now better represented, recording several ontogenetic stages previously observed in the Bolivian sample of this species. Finally, within Interatheriidae, most new dental material belongs to Argyrohyrax proavus, but an isolated upper molar suggests the presence of a different Interatheriinae at Quebrada Fiera, more similar to the Bolivian Brucemacfaddenia boliviensis than to other Deseadan (late Oligocene) taxa. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with the detailed taxonomic study of the first mammal remains from the Mariño Formation in the Divisadero Largo area, Mendoza, central west Argentina. This area was well-known by the fossils recovered from the Triassic levels and particularly by the faunal assemblage from the Cenozoic levels corresponding to the Divisadero Largo Formation. Until recently, no mammal remains had been accurately reported for the Mariño Formation, Miocene in age. The specimen consists in an almost complete upper jugal series (teeth found separated from the maxillary bone except the M3) of a small Mesotheriidae (Notoungulata), which was preliminary identified as Mesotheriinae indet. The main characteristic of these teeth is their small size, significatively lesser than that of the Miocene genera Eutypotherium, Typotheriopsis and Pseudotypotherium, being closer to Mycrotypotherium from Bolivia and the Chilean species from the Chucal Formation. The direct comparison with these latter forms has allowed a more detailed study and the recognition of the material here described as cf. Altitypotherium chucalensis, with all cautions inherent to the incompleteness of the material. [Copyright &y& Elsevier]

Late Oligocene caviomorphs represent one of the most important early adaptive radiations of this group of rodents. They show a high taxonomic diversity and a wide geographic distribution, with those found in the upper Oligocene of Salla (Bolivia) and Patagonia (Argentina) being particularly diverse. However, caviomorphs from the Deseadan South American Land Mammal Age in other latitudes are still scarcely known. In this contribution, we describe new caviomorph rodents from the Deseadan levels of Quebrada Fiera locality (Mendoza Province; central-western Argentina) and evaluate their systematic and paleobiogeographic significance. The taxonomic composition of the caviomorphs from Quebrada Fiera reveals a complex biogeographic history, as we recognize one endemic Cavioidea (Asteromys puelche sp. nov.) and two Chinchilloidea: one with Patagonian affinities (Cephalomys sp.) and another with a wide distribution in South America (Incamys bolivianus). Asteromys puelche sp. nov., shows closer phylogenetic affinities with the Bolivian A. bolivianus than with the Patagonian A. punctus. These rodents, in common with the whole mammalian association from Quebrada Fiera, show a mix of endemic taxa and others shared with higher and lower latitudes. [ABSTRACT FROM AUTHOR]

We present two new Paleogene fossiliferous sites that provide the first mammal remains for the Malargüe Group in the Neuquén basin of southeastern Mendoza Province, Argentina. Identified taxa from Agua de Flores-Agua de Isaac: Kibenikhoria sp., Oldfieldthomasiidae indet., ?Henricosborniidae indet., and a large Notoungulata probably related to the Isotemnidae. Taxa from Liu Malal: cf. Kibenikhoria and Notopithecidae gen. et sp. nov. Based on facies composition and geological distribution, we consider that the Cenozoic deposits from these fossiliferous localities correspond to the already defined Puesto Fortunata Formation. This unit is correlated to the Coihueco Formation, the top of the Malargüe Group in the northern Neuquén basin, and its mammal content supports the proposed hiatus between the ~40 Ma and 20 Ma based on chronostratigraphy. The presence of Kibenikhoria in the local faunas of southeastern Mendoza extends the geographic range of this genus so far known in Patagonia to central-west areas of Argentina and supports an early-middle Eocene age for the fossil-bearing levels of the Puesto Fortunata Formation. • First report of Eocene mammal for the Malargüe Group, Neuquén basin, Mendoza. • The fossil bearing levels belong to the Puesto Fortunata Formation. • Fossils are recognized as henricosborniid, notopithecid, oldfieldthomasiid, and isotemnid. • These mammal groups imply a faunal relationship between Mendoza and Patagonia. • Evidence reinforce a early–middle Eocene age for the fossil-bearing levels. [ABSTRACT FROM AUTHOR]