FIRST RECORD OF OSTRACODS FROM THE UPPER SILURIAN TAMBOLAR FORMATION, ARGENTINE PRECORDILLERA

MARÍA, SALAS; ANA, MESTRE; MARÍA, GÓMEZ; YANINA, GARCÍAS

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2018 vol. 55

0002-7014

Ostracods have been recovered 20 from the upper levels of the Pachaco Faciesof the Tambolar Formation of the Argentine Precordillera. Four species, of which two are new (Bollia sp. nov., Neothlipsura khiska sp. nov.), are described. An evaluation of the conodont fauna suggests an upper Silurian (Pridoli) to possibly early Devonian (earliest Lochkovian) age for the unit. The ostracod fauna is characterized by the absence of dimorphic paleocopines, forms typically abundant during the Silurian, and by the presence of Tricornina Bouček, 1936, a thin shelled spinose genus, together with representatives of Binodicopina and Metacopina (Thlipsuroidea). The taxonomic composition of the ostracods corresponds to Assemblage III of the Eifelan Mega-Assemblage or to a ?mixed assemblage?, suggesting a deep subtidal environment close to the area of the storm wave base. This interpretation is consistent with an external platform environment proposed by other authors based on stratigraphic analysis. The32 presence of ostracod taxa such as Neothlipsura khiska sp. nov. and Tricornina? sp. suggest a faunal link with the palaeocontinent of Laurentia.