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.

First Records of Late Triassic Conodont Fauna andδ13Ccarb from the Dengdengqiao Section,Dangchang County,Gansu Province,Northwestern China

Based on a study of 49 conodont and 57 geochemical samples from the Upper Triassic,carbonate-dominated Dengdengqiao Formation,Qinling Basin,China,the Carnian conodonts and carbon isotope records are first reported.Two genera and four species have been identified amongst 87 conodont elements:Mosherella praebudaensis,Mo.longnanensis sp.nov.,Mo.sp.,and"Misikella"longidentata.The presence of Mo.praebudaensis indicates that the lower part(bed 2)of the formation is attributable to the Julian(lower Carnian)substage.A radiolarian fauna identified in a previous study belongs to the upper Carnian,but the sampling horizon is unclear.Theδ13Ccarb curve shows a~1.8‰negative excursion beginning from upper part of bed 3,but its stratigraphic location is uncertain.The Dengdengqiao Formation is clearly at least partly of Carnian age but could include younger strata.The abundant calcareous algae at the section is probably due to some transport rather than preserved in site.The unusual ecosystem with rare marine organisms may reflect long-term stressful and unfavorable conditions at Dengdengqiao.

Preface

Conodonts are elements of a feeding apparatus of jawless eel-like animals belonging to the clade Vertebrata.They are very important microfossils,ubiquitous in the Paleozoic and Early Mesozoic marine sequences,and they occurred in different habitats,from deep-ocean to shallow-shelf waters.