CONICET | Buscador de Institutos y Recursos Humanos

Based on three specimens assigned to Arthrophyllum sp., the family Lamellorthoceratidae is reported from the LowerDevonian Talacasto Formation in the Precordillera Basin, central western Argentina. These Devonian cephalopods havebeen known only from low to mid palaeolatitudes and its presence in the cold water settings of southwestern Gondwana isnotable. A nektonic mode of life, not strictly demersal but eventually pelagic, with a horizontal orientation of the conch isproposed for adults lamellorthoceratids, whereas a planktonic habit is suggested for juvenile individuals. These featureswould had allow their arrival to this southern basin, explaining their unusual presence in the Malvinokaffric Realm, andreinforcing the need of re-evaluate the distribution pattern of several groups of cephalopods.