Rodighieroites belimelensis (MANDOV) (Ammonoidea) from the Taraises Formation (upper Valanginian), Durango, northeastern Mexico: biostratigraphic and paleobiogeographic implications

Abstract

This paper contributes to the knowledge of the upper Valanginian ammonite faunas of the Taraises Formation from northeastern Mexico. The fossils have been collected on a bed-by-bed basis from a predominately marly section from the state of Durango. The stratigraphic interval studied, leads to distinctive horizons defined by rich ammonite assemblages from which, stand out representatives of the species Rodighieroites belimelensis (Mandov). The presence of this taxon, along with remaining faunal elements such as Oosterella begastrensis, O. gaudryi, O. cultrata, O. cultrataeformis, Ceratotuberculus linguituberculatus, Olcostephanus ( Olcostephanus) balestrai, Olcostephanus ( Jeannoticeras) colorinensis, Karakaschiceras sp., and Bochianites spp., allowed for the assignment of these Mexican sediments to the upper Valanginian Peregrinus Zone of the standard biozonal scheme for the Mediterranean Faunal Province. This index upper Valanginian species was not hitherto recorded for Mexico or for any American locality. This new record from a western extreme of the former Tethys, increase the paleobiogeographic significance of this typical Valanginian Mediterranean ammonite species.