NEW INSIGHTS ON EARLIEST DEVONIAN (LOCHKOVIAN) OSTRACODS FROM THE ARGENTINE PRECORDILLERA

Ostracods from the Lower Devonian (Lochkovian) of the Argentine Precordillera Basin (upper levels of the Los Espejos Formation and lowermost ones of the Talacasto Formation) were studied. These units represent one of the best Lochkovian stratigraphic records in the Malvinokaffric basins. According to this revision, records of Devonian ostracod faunas in southwestern Gondwana can be extended to older stratigraphic levels. One new genus Suinella and ten species, including five new records (Suinella huarpesi gen. and sp. nov., Amphizona? argentinensis sp. nov., Bollia talacastensis sp. nov., Petrisigmoopsis? rotundum sp. nov. and Pircawayra antiqua sp. nov.) and one reassignment (Thilpsurella aff. T. putea Coryell and Cuskley) were hereby defined. The studied taxonomic assemblage differs from younger Devonian Malvinokaffric ostracod associations by being relatively diverse and composed mainly of drepanelloideans together with metacopids. The association is characterised by species with thin and spiny carapaces, a fact suggesting a relatively deep and low-energy environment below storm wave base. The mixed palaeo-biogeographic affinities of the Lochkovian ostracod fauna contrasts with the clear Malvinokaffric signature of the upper Lower-Middle Devonian associations previously recognised in Argentina.