Late middle Cambrian trilobites from El Totoral, Mendoza, Argentina

Abstract

Late middle Cambrian trilobites from open-shelf lithofacies of El Totoral, Precordillera of Mendoza, western Argentina, are described. The material belongs to the Ángel Borrello collections in the Museum of Natural Sciences of La Plata, Argentina. In addition, type specimens of the Carlos Rusconi collections in the Museum J.C. Moyano, Mendoza, are reillustrated. Biostratigraphically important agnostoids of the Lejopyge laevigata Zone [Agnostus microcephalus (Rusconi), Ammagnostus beltensis (Lochman), Kormagnostus seclusus Walcott, Clavagnostus calensis Rusconi, Tomagnostella nepos (Brøgger), Lejopyge sp.] are described from this locality for the first time, and the polymeroid faunas are fully revised. The latter include Asaphiscus cf. lasherensis (Rusconi), Blountia socorrensis Rusconi, Elrathia oscelata (Rusconi), Talbotinella communis Poulsen, Modocia sp., Olenoides faldeanus Rusconi and Hysteropleura (Verditerrina) totoralensis (Rusconi). As previously suggested by Borrello and Rusconi, the polymeroids have their closest affinities with faunas of North America (lower Cedaria Zone and equivalents).