Three groups of unusual microfossils in the Pennsylvanian and Permian succession in midcontinent North America

This thesis includes descriptions of three unusual groups of microfossils from the Pennsylvanian and Permian succession of Midcontinent North America. Most of the locations were discovered during the examination of acid insoluble residues of shales and limestones, while working on various projects involving conodont biostratigraphy. Locations vary from near Des Moines, Iowa in the north, to northwest Missouri, eastern and south-central Kansas, and near Tulsa, Oklahoma in the south. Locations range in age from the Excello Shale in the upper Desmoinesian Stage (Pennsylvanian) to the Fort Riley Limestone in the lower Artinskian Stage (Permian). Fossil groups include radiolarians, chitinozoans, and chitinozoan-like organic-walled microfossils. All fossil groups contain very small individuals (62--2500mu) and require imaging by a scanning electron microscope (SEM) to identify and study morphology.; The radiolarians (Chapter I) represent the first known occurrence of abundant relatively well-preserved specimens from Midcontinent North America. The radiolarians are from the Excello Shale, lower Marmaton Group (Desmoinesian, Pennsylvanian) of south-central Iowa, and include pseudoalbaillellids and both spherical and stauraxon spumellarians.; The chitinozoans (Chapter II) were previously reported from the Leavenworth Limestone and Fort Riley Limestone (Virgilian and Artinskian stages respectively) of eastern Kansas, and this report extends the geographical range into northwest Missouri in the Larsh-Burroak Shale (Virgilian) and into northeastern Oklahoma in the Eudora Shale (Missourian). They include Rhabdochitina, Euconochitina, Lagenochitina, and Sphaerochitina of the Order Prosomatifera.; The chitinozoan-like organic-walled microfossils (Chapter III) were also previously reported from the Leavenworth Limestone (Virgilian) and the Fort Riley Limestone (Artinskian) of eastern Kansas, but they had never been described morphologically. They have also now been found in abundance in the lower Lane Shale (Missourian) of Iowa, Larsh-Burroak Shale (Virgilian) of Missouri, and lower Eudora Shale (Missourian) of Oklahoma. Their biological affinity is still unknown, but they may represent Polychaete worm egg cases.; All three groups of microfossils are related to their utility in biostratigraphy and to their position within transgressive-regressive sequences (cyclothems). Radiolarians and the organic-walled microfossils occur in abundance only in facies of the highstand system tract, while the chitinozoans occur as rare fossils in all system tracts. Only the radiolarians seem useful in biostratigraphic correlation, and paleogeographic reconstruction.