Smithian (Early Triassic) ammonoid faunas from Timor: taxonomy and biochronology

Abstract

Two extensive collections retrieved from West Timor have yielded several astonishingly well-preserved and highly diversified Smithian (Early Triassic) ammonoid faunas (Kashmirites fauna, Owenites fauna, Anasibirites fauna). A population approach on this material, with an emphasis on ontogeny and covariation of morphological characters, led to the unprecedented assessment of intraspecific variation for many species. Based on this, their synonymy is thoroughly discussed whenever possible. One new genus (Roopnarinites) and five new species (Paraspidites bicarinatus Flemingites lidakensis Subflemingites bihatiense Baidites obesus and Churkites warei) are described. These results have a direct impact on the resolution and accuracy of biochronological correlations, as well as on the accuracy of diversity counts at the species level, which is important for potential future broad-scale diversity analyses. This material also provides highly valuable data for comprehensive biogeographical and phylogenetic studies hopefully to come. Finally, these new Timor data strengthen the singularly uniform biogeographical distribution of the Smithian ammonoid faunas within the Tethys.