A new Metapolygnathus platform conodont species and its implications for Upper Carnian global correlations

摘要

A rich conodont fauna from two Neotethyan sections, Pizzo Mondello (western Sicily, Italy) and Pignola 2 sections (southern Apennines, Italy) includes conodonts described herein as a new species. Metapolygnathus praecommunisti sp. nov. is transitional between Paragondolella noah and Metapolygnathus communisti. The genus Metapolygnathus (in− cluding M. praecommunisti) is now characterised by posterior prolongation of the keel termination, associated with a cen− trally located pit and with a weak ornamentation confined to the anterior part of the platform margins. The establishment of M. praecommunisti addresses the problems related to the origin and the peculiar, probably facies−controlled, distribu− tion of its descendant species M. communisti. Since M. praecommunisti occurs in the entire Tethys and in North America, we propose the species as a good guide fossil for global correlations, characterised by a short temporal range limited to the uppermost Tuvalian (upper Carnian). The stratigraphic occurrence of the genus Metapolygnathus is restricted to the Tuvalian–Lacian (upper Carnian–lower Norian), excluding its presence in the Julian substage (lower Carnian).