Evolutionary trends of the genus Ancyrogondolella (Conodonta) and related taxa in the Norian (Late Triassic)

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