Mammalian diversity and age of the Salicas Formation (Late Miocene–Early Pleistocene), Northwestern Argentina: State of knowledge and new contributions.

Late Cenozoic sediments in the Sierras Pampeanas of La Rioja and Catamarca provinces, Northwestern Argentina, have yielded fossil mammal remains from the Salicas Fm. Herein, we provide a taxonomic review of previously published material and new fossils from El Degolladito area, plus the San Blas area, and north of the Sierra de Mazán region (Villa Mervil, Villa Mazán, Santa Teresita, and Salar de Pipanaco localities). Zircon dating of volcaniclastic levels of the Salicas Fm localities reveals that the fossil vertebrates span from ca. 8.7 to 2.4 Ma (Late Miocene–Early Pleistocene), which in El Degolladito area (ca. 8.7–7.9 Ma) is more abundant and taxonomically rich and includes Metatheria (cf. Thylatheridum sp., Lycopsis sp.), Rodentia (Cardiomys sp., Prodolichotis prisca , Caviidae sp. A., Lagostomus pretrichodactyla , Metacaremys primitiva , Pseudoplataeomys elongatus , Tetrastylus sp.), Meridiungulata (Neobrachytherium sp., Hemihegetotherium torresi , Paedotherium minor , Protypotherium minutum , Typotheriopsis sp.), and Xenarthra (Eosclerocalyptus proximus , Stromaphorus compressidens , Nopachthus coagmentatus , Chasicotatus peiranoi , Paleuphractus argentinus , Proeuphractus limpidus , Prozaedyus sp., Vetelia gandhii , Pampatheriidae indet, Pilosa indet.). Lagostomus cf. L. pretrichodactyla , H. torresi , and Vetelia sp. have also been recovered in the outcrops near San Blas (without dating), whereas to the north of the Sierra de Mazán (ca. 5.7–2.4 Ma) only remains Dasypodidae, Glyptodontoinei, and N. coagmentatus have been found. Based on our analysis, it seems that the sampling conducted in El Degolladito area may have not yet fully uncovered the complete range of mammal diversity. The association from El Degolladito share affinity with those of the Late Neogene of Argentina previously referred to "Chasicoan" and "Huayquerian", like Palo Pintado Fm, "Chasicoan" faunas of Cerro Azul Fm (e.g., Cerro La Bota locality), Loma de Las Tapias assemblages A and B, which is congruent with the absolute dating obtained. • First zircon dating suggests Salicas Formation's deposition during Late Miocene to Early Pleistocene (ca. 8.7–2.4 Ma). • Mammalian assemblage at El Degolladito site (Late Miocene, Tortonian) shows affinity with Chasicoan and Huayquerian faunas. • New data expands Salicas Formation's mammal diversity in 27 taxa. [ABSTRACT FROM AUTHOR]