Revision of the Conodont Mockina slovakensis and Its Paleogeographic Implications for the Upper Triassic Intraplatform Basins of the Alps

Mockina slovakensis,thought to have evolved from Epigondolella praeslovakensis,is an important species of the Norian(Upper Triassic),generally considered as the representative of the uppermost Alaunian to upper Sevatian in the Tethys.The previous description of M.slovakensis was incomplete,thus has led to some misidentifications.We thus update the description of M.slovakensis and discuss its comparisons and occurrence based on the new conodont investigations in Dolomia di Forni and the data from previous literatures.The conodont assemblage in the succession of Dolomia di Forni is dominated by M.slovakensis,along with rare M.postera and E.praeslovakensis.We described two morphotypes of M.slovakensis(morphotypes A and B),on the basis of shape of the lateral profile.These two morphotypes can also be observed in the E.praeslovakensis.Moreover,M.slovakensis is usually documented as almost monospecific conodont association in intraplatform basins,thus its paleogeographic implications are also discussed.

Evolutionary Process from Mockina bidentata to Parvigondolella andrusovi:Evidence from the Pizzo Mondello Section,Sicily,Italy

During their last phase of evolution,the pectiniform conodont elements manifested an evident trend of simplification and miniaturization.This phase started from the late Norian(Sevatian)in the Late Triassic and the evolutionary process of genus Mockina to Parvigondolella,in particular between Mockina bidentata and Parvigondolella andrusovi,is one of the most significant examples.Parvigondolella has been reported worldwide since it was first described in the early 1970s.However,it has recently been suggested that genus Parvigondolella is an ecostratigraphic morphotype of genus Mockina,and thus a phenotype controlled by the environmental conditions,and not an independent taxon.In the Pizzo Mondello Section(Sicily,Italy),transitional forms between M.bidentata and P.andrusovi have been found at different evolutionary stages.We have investigated the oceanic conditions at the time by using redox-sensitive elements(Mn,Fe,V,Cr,and Ni)and seawater temperatures from biogenetic δ^(18)Ophos to understand the possible environmental influences on the phylogenetic evolution between Mockina and Parvigondolella.The geochemical and isotope analyses indicate that the redox condition and temperature were stable during the evolution of genus Parvigondolella in Pizzo Mondello,confirming that genus Parvigondolella is a real taxon and not a phenotype.A new conodont species named Parvigondolella ciarapicae n.sp.is described here for the first time.

Evolutionary Trends of the Genus Ancyrogondolella(Conodonta)and Related Taxa in the Norian(Late Triassic)

The Norian represents the longest stage of the Triassic,nevertheless,its precise subdivision is an unresolved matter.Conodonts might be useful in the establishment of an accurate biozonation to avoid common scientific misinterpretations.Understanding the Norian evolutionary trends and morphological changes of the Ancyrogondolella lineage(genus Ancyrogondolella and descendant genera Epigondolella,Orchardella and Mockina)is of key importance in this issue.The forward shifting of the pit and the posterior prolongation of the keel and the carina characterize the main trend that corresponds to the faunal turnover around the Lacian-Alaunian transition.A gradual decrease in overall element width and length can be observed from that time on,which couples with a decrease in the length of the free blade and an increase in the height of the anterior platform denticles.The presence of secondary carinae is characteristic for the mid-Lacian 1 to Alaunian 1,but their development shows no trends and has no taxonomic value.Adult specimens of the Lacian generally have an arched lower profile,whereas in the Alaunian and Sevatian the lower profile is dominantly stepped or straight.The thorough documentation of the Tethyan assemblages is needed for any detailed taxonomic and paleobiogeographic comparisons with other regions.

New Advances in Biostratigraphy of the Lower/Middle Norian Transition:Conodonts of the Dov?ko Section,Slovenia

This study presents the results of the conodont biostratigraphy and microfacies analysis carried out on the pelagic limestones of the Upper Triassic Dov?ko Section in Slovenia,which represents the eastern part of the Slovenian Basin.The age of the section ranges from the Lacian 1 to the Alaunian 1.The Lacian part of the succession is predominantly characterized by the representatives of the genus Ancyrogondolella.Transitional morphologies towards Alaunian faunas first appear in the Lacian 3 and become common during the Lacian-Alaunian transition.This evolutionary development coincides with a shift in microfacies from a dominantly radiolarian-bearing mudstone-wackestone-packstone to a filament-dominated wackestone-packstone,and the formation of small neptunian dykes,which may reflect environmental perturbations and/or a change in basin geometry.The proliferation of the genera Epigondolella and Mockina is observed in the Alaunian part of the section,though the genus Ancyrogondolella is still present in this interval.Systematic description of the conodont taxa is provided,and seven new species and two new subspecies are established.The new advances will be of great value in further biostratigraphic studies,especially in areas without ammonoid faunas,and in the reconstruction of the paleogeography of the Slovenian Basin.