The vertebrate fossil record of the Pampean Region of Argentina occupies an important place in South American vertebrate paleontology. An abundance of localities has long been the main basis for constructing the chronostratigraphical/geochronological scale for the late Neogene–Quaternary of South America, as well as for understanding major patterns of vertebrate evolution, including the Great American Biotic Interchange. However, few independently-derived dates are available for constraining this record. In this contribution, we present new 40Ar/39Ar dates on escorias (likely the product of meteoric impacts) from the Argentinean Atlantic coast and statistically-based biochronological analyses that help to calibrate Late Miocene–Pliocene Pampean faunal successions. For the type areas of the Montehermosan and Chapadmalalan Ages/Stages, our results delimit their age ranges to 4.7–3.7 Ma and ca. 3.74–3.04 Ma, respectively. Additionally, from Buenos Aires Province, dates of 5.17 Ma and 4.33 Ma were recovered for “Huayquerian” and Montehermosan faunas. This information helps to better calibrate important first appearances of allochthonous taxa in South America, including one of the oldest records for procyonids (7.24–5.95 Ma), cricetids (6.95–5.46 Ma), and tayassuids (> 3.74 Ma, oldest high-confidence record). These results also constrain to ca. 3 Ma the last appearances of the autochthonous sparassodonts, as well as terror birds of large/middle body size in South America. South American faunal turnover during the late Neogene, including Late Pliocene extinctions, is interpreted as a consequence of knock-on effects from global climatic changes and initiation of the icehouse climate regime.

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Holocene landscape development in tHe el Bolson Basin: people, environment, and processes of cHange and staBility Julio Kulemeyer a , liliana lupo b , m. carolina madozzo Jaén c , alicia cruz d , patricia cuenya e , mariana maloberti f , gabriel cortés g y alejandra Korstanje h El valle de El Bolsón (Departamento de Belén, Catamarca, Argentina) tiene una larga historia de ocupaciones, sobre todo desde el inicio de la agricultura hasta la actualidad. Se presenta una primera integración local interdisciplinaria, utilizando diferentes proxies (sedimentos, suelos, mamíferos, polen y otros microfósiles) para contribuir a la primera discusión de los procesos de estabilidad y cambio en la historia social, paleoclimática y el medio ambiente en el valle durante el Holoceno. En tal sentido, observamos importantes cambios ambientales durante el Holoceno Tardío, que se manifiestan en forma de procesos de acumulación y erosión, cambios de uso del suelo e influencia antropogénica sobre los frágiles ecosistemas semiáridos en el contexto de las variaciones paleoclimáticas. Palabras claves: cambio ambiental, paisajes agrarios, interdisciplina. the valley of el Bolsón (department Belén, catamarca, argentina) has a long history of occupations, mainly since the beginning of agriculture until today. We present a first local interdisciplinary integration using different proxies (sediments, soils, mammals, pollen and other microfossils), to contribute to the first discussion of the processes of stability and change in social history, paleoclimate and environment in the valley during the Holocene. We observed significant environmental changes during the late Holocene, which manifest in the form of accumulation and erosion processes and changes in land use and anthropogenic influence on the fragile semi-arid ecosystems in the context of paleoclimatic variations.