Bathyuriscus mendozanus (Rusconi, 1945), middle Cambrian trilobites from the Argentine Precordillera.

Abstract

Bathyuriscus mendozanus, a valid species differentiated from the 19 laurentian species accepted for this genus. As well, previous open nomenclature Bathyuriscus specimens and new materials collected by the authors are included. The most fossils occur commonly in the cambrian olistoliths with outer platform mudstones, hosted in pelitic ordovician sequences. The trilobites were found in Quebrada Ojos de Agua, Quebrada Los Sombreros, Cordón del Alojamiento and San Isidro localities, from the Argentine Precordillera. The biostratigraphic distribution of the B. mendozanus is middle Cambrian, Marjumian Stage, Oryctocephalus Zone in the conventional laurentian chronology, which is equivalent in the International Subcommission on Cambrian Stratigraphy (ISCS) scale to the Cambrian Series 3, upper Stage 5 of Cambrian. Its presence in western Argentina is further evidence for the very close faunal relationship between the Precordilleran Terrane and Laurentia during the Cambrian.