UN AMONITE HETEROMORFO (SPIROCERATIDAE) DEL BAYOCIANO SUPERIOR DEL PASO DEL ESPINACITO, SAN JUAN, ARGENTINA

M. Beatriz Aguirre Urreta, P. Pamela Alvarez

Abstract


AN HETEROMORPHOUS AMMONITE (SPIROCERATIDAE) OF UPPER BAJOCIAN AGE FROM PASO DEL ESPINACITO, SAN JUAN, ARGENTINA. The species Spiroceras orbignyi (Baugier y Sauzé) is recorded from the upper levels of the Los Patillos Formation in the Paso del Espinacito area, Principal Cordillera of San Juan. S. orbignyi shows a widespread geographic distribution but is stratigraphically restricted to the Upper Bajocian. In the local ammonoid zonation it can be placed in the Megasphaeroceras magnum Assemblage zone, which is partially equivalent to the Upper Bajocian Submeditarrean Subfurcatum(=Niortense) and Garantiana zones. This finding represents the first record of the genus Spiroceras from Argentina.

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