ABSTRACT: The most complete, abundant and diverse Middle–Upper Pennsylvanian ammonoid succession in the world occurs in the North American Midcontinent, where more than 40,000 ammonoids representing 52 genera from at least 42 successive stratigraphic levels have been recovered. The Desmoinesian–Virgilian succession comprises a series of seven substage-scale ammonoid genus zones, in ascending order: Wellerites, Eothalassoceras, Pennoceras, Preshumardites, Pseudaktubites, Shumardites and Subperrinites (new), which are subdivided into 14 ammonoid species- or genus-based subzones. The base of the Eothalassoceras Zone is near the current base of the global Kasimovian Stage, the base of the Pennoceras Zone coincides with the base of the regional Missourian Stage (and likely will be close to the base of a revised Kasimovian Stage when its official base is formally selected), the base of the Pseudaktubites stainbrooki Subzone nearly coincides with the base of the regional Virgilian Stage, and the base of the Shumardites Zone coincides with the base of the global Gzhelian Stage, illustrating the value of this zonation for regional and global correlation.
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