Conodont taxonomy and the recognition of them Frasnian/Famennian (Upper Devonian) Stage Boundary

The boundary-stratotype for the base of the Famennian Stage at Coumiac in the Montagne Noire, southern France, was defined so as to coincide with the lower boundary of the Lower triangularis conodont zone. The definition of that biostratigraphic zone has to bemodified in light of the present taxonomic distinction between Palmatolepis triangularis and a closely related species, P. ultima. As a result, P. triangularis no longer first occurs at the base of its nominal zone, but enters upwithin the zone. A revision of the lower boundary of the Lower triangularis Zone, defined by the flood occurrence of P. ultima immediately above the end-Frasnian conodont extinction event, is recommended and does not alter the boundary-stratotype (GSSP) in anyway. The focus of the paper is the taxonomic distinction of two pairs of Palmatolepis species that have been widely confused in the literature and that affect the recognition of the Frasnian/Famennian boundary.