CONICET | Buscador de Institutos y Recursos Humanos

This paper contains the taxonomic and biostratigraphic analysis of a new Tithonian ammonite fauna from the Neuquén Basin, Argentina. Most of the ammonites have been collected by the authors bed by bed in the lithographic limestone quarries of the Los Catutos region in the vicinity of Zapala city. Some additional material from Cerro Caicayén and Cerro Lotena has been contributed by the Olsacher Museum of Zapala. The new subfamily Windhauseniceratinae has been established within the Ataxioceratidae Buckman, 1921; it consists of the two new tribes Windhauseniceratini (with the new species Windhauseniceras stipanicici sp. nov.) and Catutosphinctini (with two new genera and nine new species): Mapuchesphinctes gen. nov., with M. garatei sp. nov., (type species), Parazapalia gen. nov. with P. hillebrandti sp. nov. (type species) and P. perezi sp. nov., Catutosphinctes callomoni sp. nov., C. westermanni sp. nov., Zapalia zapalensis sp. nov., Z. triplex sp. nov., Z. poultoni sp. nov., and Z. thomsoni sp. nov. Within the Aspidoceratidae the new species Aspidoceras quinchaoi sp. nov. has been established. The age of the described fauna is regarded as Late Middle Tithonian to Early Upper Tithonian. The fauna is encompassed in the upper part of the Proximus Zone (level x+a) and in the Internispinosum Zone (levels x, y, z, w), which in turn is divided in the Catutosphinctes rafaeli and the Zapalia fascipartita subzones. In the latter the horizons of Aspidoceras quinchaoi and Djurjuriceras catutosense have been recognized. The most important result of this study is the refinement of the biostratigraphy of the Andean Middle and Upper Tithonian in the Neuquén Basin. The significance of the Internispinosum Zone for global correlation at the base of the Upper Tithonian is also discussed.