Document Type



Ammonoids, Mississippian Ammonoids


Lower Mississippian rocks in the type area of North America have produced only a few scattered ammonoid cephalopods. Those specimens from southeastern Iowa and northwestern Missouri lie within the general vicinity of the designated type locality, near Kinderhook, Illinois. In this area, age relationships for strata near the Devonian-Mississippian boundary have been established largely through studies of their conodont faunas. However, some of the ammonoids from within the Kinderhook and adjacent beds are critical for long-range correlation. Although most of these ammonoid occurrences have been recorded, minor changes in correlation can be suggested by reexamination of the specimens, together with a review of the physical stratigraphy and the associated conodont faunal data. The Kinderhookian Wassonville Member of the Hampton Formation in southeastern Iowa and the Chouteau Limestone of Missouri fall within the lower "Pericyclus-Stufe" of the upper Tournaisian Stage as these units are designated for the early Lower Carboniferous of Western Europe. The index genus is present, but relatively rare in North America; associated ammonoids include Gattendorfia, Prodromites and Imitoceras. All of these genera are known from the type Kinderhook area. The same genera, plus Muensteroceras and Beyrichoceras appear to characterize the overlying Osagean beds. The directly underlying Upper Devonian also contains Imitoceras, but Cymaclymenia and Cyrtoclymenia in addition.

Publication Date

March 1973

Journal Title

Proceedings of the Iowa Academy of Science





First Page


Last Page



©1973 Iowa Academy of Science, Inc.



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