An Early Ordovician conodont fauna from the Santa Rosita Formation at its type area in the Santa Victoria Range, Cordillera Oriental, Northwestern Argentina

Abstract

The Cambrian - Lower Ordovician stratigraphic units from the Cordillera Oriental were originally defined in the Santa Victoria Range, Salta Province, northwestern Argentina, however, the extensive outcrops of this region lack detailed biostratigraphic studies. We describe and analyse the first reported conodont fauna from the Santa Rosita Formation at its type area, which produced significant biostratigraphic information. Over 4,500 well-preserved conodont elements were recovered from outcrops of the Santa Rosita Formation at the southern margin of the Santa Victoria River, near the homonymous locality. Collected specimens exhibit a CAI 3 and correspond to the Paltodus deltifer deltifer Subzone of the P. deltifer Zone (middle Tremadocian, Tr2). A number of species are described for the genera Acanthodus, Acodus, Decoriconus, Drepanodus, Drepanoistodus, Filodontus, Granatodontus, Hammannodus, Iapetonudus, Kallidontus, Paltodus, Paroistodus, Teridontus, Tilcarodus, Utahconus, Variabiloconus, Gen. and sp. indet., the protoconodont Phakelodus and the paraconodont Coelocerodontus. Two new conodont species, Drepanoistodus andinus Voldman, Zeballo and Albanesi and Filodontus carolinae Voldman, Albanesi and Zeballo, are diagnosed herein. The studied assemblages include conodont species of wide intercontinental distribution as well as endemic forms from the Central Andean Basin, which characterize a faunal province with a particular signature from the Shallow Water Realm.