EVOLUTION OF SOME LOWER PENNSYLVANIAN CONODONT SPECIES

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Abstract

The closely related conodont species Idiognathoides noduliferus and Idiognathoides sulcatus underwent morphologic diversification in the lower Morrowan (Lower Pennsylvanian). The expanding range of variation of the two progenitor species overlapped, producing a completely intergraded morphologic-continuum. Non-intergradation and taxonomic differentiation at stratigraphically higher levels in the Morrowan demonstrate that certain morphotypes within the continuum bore the potential of becoming descendant species. The descendant species include Idiognathoides sinuatus, Idiognathoides macer, and Gnathodus bassleri symmetricus, Conventional systematic techniques are inadequate to depict the morphologic complexity and evolution shown by this example.

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