GRAPTOLITOS CARADOCIANOS DE LA FORMACION YERBA LOCA Y DEL Cº. LA CHILCA - DPTO. JACHAL, PROVINCIA DE SAN JUAN

A graptolite fossil assemblage from the Yerba Loca Forrnation at Cuesta del Viento, Rodeo (Departamento Jachal, Province of San Juan) characterized by Nemagraptus gracilis and Corynoides tricornis turneri (the latter being the First mention in South America of the Corynoid idae Family ) has indicated a Lower Caradocian age. At Cerro La Chilca (departamento [achal ), shales overlying the San juan Forrnation furnished a different assemblage, in which Dicellograptus dicaricatus salopiensis, the dominant form, plus Leptograptus flacculus macer define an Upper Caradocian age. Some species of Leptograptus found in both graptofaunas are the first forms of this genus describecl for Argentina. Systematic includes all the graptolites studied plus new arthropod trace Fossils from the Yerba Loca Formation.