Evolution of the Lower Carboniferous conodont genus Mestognathus

Abstract

A new species of the conodont genus Mestognathus is recognized in the Lower Carboniferous carbonates of the Cracow Upland, southern Poland. It appears much earlier than the base of the Lower Visean, from which the genus Mestognathus has hitherto been noted. The phyletic lineage of M. groessensi sp.n. → M. beckmanni → M. bipluti, Middle Tournaisian to lowermost Namurian in age, is shown from the carina and the inner parapet characteristics which illustrate a progressive trend in the evolution of Mestognathus. Additionally, the taxonomy of the genus Mestognathus is revised. It is suggested that Mestognathus was restricted only to the shelf area, from its margin to the intertidal zone. The rare basinal settings of this ,genus are interpreted as a result of synsedimentary redeposition affected by basinward debris flow.