Earliest Permian brachiopod faunas of west-central Argentina: Defining the Pennsylvanian–Permian boundary in Gondwana

Late Palaeozoic marine successions in the west-central Argentinian basins have one of the most complete stratigraphic records of the earliest Permian in Gondwana. Two brachiopod faunal assemblages characterize this interval: the Tivertonia jachalensis–Streptorhynchus inaequiornatus fauna, widely documented in the Río Blanco and western Paganzo basins; and the Costatumulus amosi fauna identified in the earliest Permian successions of the southern Calingasta–Uspallata Basin. This study reviews the composition and biostratigraphy of these two brachiopod faunas with special reference to their global significance for defining the Carboniferous–Permian boundary in Gondwana and deciphering the Early Permian climate change in western Gondwana.