Fryxellodontus inornatus (Conodonta) and associated conodonts from the Furongian (upper Cambrian) of the Cordillera Oriental, Argentina

Abstract

The conodont biostratigraphy of the middle-upper Lampazar Formation exposed at El Angosto del Moreno area, Cordillera Oriental of Jujuy, Argentina is analyzed. This 150 m thick unit overlies the Padrioc Formation (late Cambrian) and underlies the Cardonal Formation (late Cambrian–early Tremadocian). The unit is composed of pelites interbedded with sandstones and calcarenites and occasional coquinas, which were deposited primarily in offshore environments. Two calcarenite samples (3200 g) yielded 599 conodont elements, corresponding to 35 species of the genera Coelocerodontus, Cordylodus, Eoconodontus, Eodentatus, Fryxellodontus, Furnishina, Granatodontus, Hirsutodontus, Phakelodus, Proconodontus, Prooneotodus, Prosagittodontus, Teridontus, and Anellodontus n. gen. The recovered specimens are well preserved, exhibiting a Color Alteration Index (CAI) value of 1.5–2, which represents overburden palaeotemperatures between 50 C and 140 C. The conodont association corresponds to the upper part of the Cordylodus proavus Zone, indicating a late Furongian age for the sample levels. This contribution reports the first conodont record of Fryxellodontus inornatus and F. lineatus species, the genus Eodentatus, and a new genus Anellodontus n. gen. in South America.