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In recent decades, Miocene marine transgressions in South America have sparked ongoing debates concerning their boundaries, number of events, regional connectivity, and the existence of an epicontinental sea formed during the Andean orogeny. The bed-by-bed analysis of the Late Miocene Paraná Formation deposits in Entre Ríos Province (Argentina) allow defining six facies associations: (i) beach ridge, (ii) tidal inlet channel and washover fan, (iii) outer estuarine bioherms, (iv) central estuary, (v) tidal bar and sandflat, and (vi) tidal mudflat and creek deposits. Architectural and stacking pattern analyses reveal transgressive-regressive sequences typical of the coastal strip, encompassing shallow marine to estuarine sub-environments. The analysis identified diverse ecological guilds, including bivalve and gastropod assemblages in bioherms, and crustacean traces in tidal flats. Regressive units are characterized by wave-dominated shoreface deposits, while transgressive units comprise fine-grained estuarine deposits interbedded with bioclastic sandstones and storm deposits. The paleoenvironmental and paleoecological data indicate normal salinity marine environments with macroinvertebrates and estuarine components and suggesting tropical brackish conditions. Plant remains point to a range of vegetative communities, including mangroves, palm forests, grasslands, humid riparian forests, and dry upland forests, reflecting tropical to subtropical and humid to semiarid environments. This study concludes that the Paraná Formation correspond to a third-order transgressive system tract influenced by the Miocene Paranaense Sea. The basin-scale implications suggest that the distal Chaco-Paraná basin was affected by eustatic changes due to its low accommodation and topographic relief. The Chaco-Paraná foreland basin's evolution was driven by interactions between tectonic, climatic, and eustatic processes. The comprehensive analysis of sedimentary and fossil records provides a detailed paleogeographic reconstruction of the Miocene marine transgression in southern South America. • Estuarine to shallow marine depositional environments identified in the Paraná Formation. • Integrated stratigraphic, depositional and paleoecological data for the reconstruction of the Paraná Formation. • Proposal of a sequential stratigraphic model for the beginning of the Chaco-Paraná foreland basin during the Cenozoic. • Tectonic, eustatic and climatic influences on the regional development of the Central Andes of South America are discussed. [ABSTRACT FROM AUTHOR]

We present the first record of an extinct procyonid for Bolivia (Tariquía Formation, La Angostura, Santa Cruz de La Sierra; Late Miocene). It corresponds to Cyonasua , the first Carnivore taxon to enter South America from North America before the Paniamian Isthmus raised and as a part of the "proto Great American Biotic Interchange" (GABI). Cyonasua fossil record, comprises the temporal lapse late Miocene to early Pleistocene in several localities of Argentina, Venezuela and Uruguay. This genus encompasses ten formally named species: C. argentina , C. brevirostris , C. longirostris , C. pascuali , C. groeberi , C. lutaria , C. clausa , C. robusta , C. argentines , and C. meranii. The mandible and teeth preserved of the new specimen, YPFBLIT-PAL-020, allows us to assign it to Cyonasua cf. C. pascuali. This record reinforces the paleoenvironment with warm climates and humid environments with abundant water bodies, vegetation and trees proposed previously for Tariquia Fm. Also, the proposed Huayquerian Age for this Formation is supported by this record. • On this contribution we present the first record of an extinct procyonid for Bolivia (Tariquía Formation, La Angostura, Santa Cruz de La Sierra; Late Miocene). • It corresponds to Cyonasua, the first Carnivore taxon to enter South America from North America before the Paniamian Isthmus raised and as a part of the "proto Great American Biotic Interchange" (GABI). • Cyonasua fossil record, comprises the temporal lapse late Miocene to early Pleistocene in several localities of Argentina, Venezuela and Uruguay. • The mandible and teeth preserved of the new specimen, YPFBLIT-PAL-020, allows us to assign it to Cyonasua cf. C. pascuali. • This record reinforces the paleoenvironment with warm climates and humid environments with abundant water bodies, vegetation and trees proposed previously for Tariquia Fm. • Also, the proposed Huayquerian Age for this Formation is supported by this record. [ABSTRACT FROM AUTHOR]