CONODONT BIOSTRATIGRAPHY OF THE VIRGILIAN STAGE, KANSAS

Conodont faunas of the uppermost Pennsylvanian are dominated by species loosely ascribed to the genera Idiognathodus and Streptognathodus. These genera have been poorly understood and generally treated as represented by a few long-ranging species. Detailed examination of these “species” shows that they are clades of several distinct species and can be used to differentiate most of the cycles that make up the Virgilian Stage in Kansas and Missouri. Specifically, the conodont clades characterized by asymmetric paired Pa elements as exemplified by Idiognathodus simulator and Streptognathodus bellus are very useful. Streptognathodus bellus gave rise to a succession of species, one of which defines the internationally recognized base of the Permian, Streptognathodus isolatus. In Kansas, Streptognathodus isolatus first occurs at the base of the Bennett Shale Member of the Red Eagle Limestone. The proposed base of the international Gzhelian Stage is the first occurrence of Idiognathodus simulator (sensu strictu) which occurs in its type stratum, the Heebner Shale Member of the Oread Limestone. Most maximum flooding surfaces appear to contain a different species of this clade, distinguished by apparatuses with very asymmetric paired Pa elements. The conodont faunas of the Douglas, Shawnee, Wabaunsee, Admire and lower Council Grove Groups, which constitute the uppermost Pennsylvanian or North American “Virgilian” Stage, are reviewed.