The oldest record of Eothinoceratidae (Ellesmerocerida, Nautiloidea): Middle Tremadocian of the Cordillera Oriental, NW Argentina

Middle Tremadocian cephalopods from the Sierra de Mojotoro, Cordillera Oriental, NW Argentina, are assigned to Saloceras cf. sericeum (Salter) based on the siphuncle morphology and general shape of the conch. Saloceras sericeum (Salter) is known from the Upper Tremadocian and Floian of England and Wales, a region that formed part of eastern Avalonia during the Early Ordovician, located at a high southern latitude to the north of the Gondwanan margin. This is the oldest record of this genus and of the family Eothinoceratidae, and extends the geographical range of Saloceras, being the first positive record of its presence in Argentina and the Central Andean Basin. These remains are amongst the oldest cephalopods described from NW Argentina. They represent the third mid Tremadocian record of nautiloids at relatively high palaeolatitudes and away from the low latitude carbonate platform palaeoenvironments where the bulk of the earliest cephalopods resided. Fil: Cichowolski, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Vaccari, Norberto Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina