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

作　　者：Viktor Karadi 

机构地区：[1]Department of Palaeontology,Eotvos Lorand University,Budapest 1117,Hungary

出　　处：《Journal of Earth Science》2021年第3期700-708,共9页地球科学学刊（英文版）

基　　金：Funding for this research was provided through the NKFIH PD-131536 Project and the Hantken Miksa Foundation。

摘　　要：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.

关 键 词：CONODONTS evolution Ancyrogondolella Late Triassic NORIAN Lacian Alaunian Sevatian 

分 类 号：P534.51[天文地球—古生物学与地层学] Q915[天文地球—地质学]