Conodonts are accepted internationally to define Devonian Series and Stage boundaries. Hence, the evolution and taxonomy of pelagic palmatolepids, primarily Palmatolepis and its direct ancestor Mesotaxis, and shallow-water icriodontids, Icriodus, Pelekysgnathus, and "Icriodus", are the major tools for recognizing subdivisions of the Upper Devonian. Palmatolepids are the basis for the Late Devonian Standard Conodont Zonation (ZIEGLER & SANDBERG 1990), whereas icriodontids are the basis for the alternative, integrated shallow-water zonation (SANDBERG & DREESEN 1984). However, an alternative palmatolepid taxonomy for some Frasnian species has been employed recently by some conodont workers using the Montagne Noire (M.N.) zonation, shape analyses of Pa elements, and multielement reconstructions of KLAPPER (1989), KLAPPER & FOSTER (1993); and KLAPPER et al. (1996). Herein, the evolution of palmatolepids and icriodontids is summarized in terms of our zonation and some of the taxonomic differences with the alternative M.N. zonation are exemplified. One of the problems in relating the Standard and M.N. zonations arises from previous errors of interpretation and drafting of the Martenberg section in Germany. This section was designated the reference section for the Frasnian transitans through jamieae Zones by ZIEGLER & SANDBERG (1990). Herein, the early and middle Frasnian zonal boundaries at Martenberg are improved by re-study of our old and recent collections from three profiles, spaced only 4 m apart. Serious problems exist with the Global Stratotype Sections and Points (GSSP's), selected by the Subcommission on Devonian Stratigraphy, following the paleontologic definition of the bases of the Frasnian, Famennian, and Tournaisian Stages, because of the difficulty in making global correlations from these GSSP's. Our summary of these problems should be helpful if future workers decide to relocate these GSSP's.
Additional publication details
Utility of palmatolepids and icriodontids in recognizing Upper Devonian Series, Stage, and possible substage boundaries