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Pennsylvanian rocks at Arrow Canyon have been proposed as a stratotype for the base and top of the Pennsylvanian System and for the "Atokan" Series. Fusulinaceans and conodonts document an essentially continuous biostratigraphic succession, and detailed petrographic descriptions have been published. Systematic descriptions and local ranges for the extensive and biostratigraphically significant brachiopod fauna are, as yet, unpublished. This report on brachiopods from the Zone of Fusulinella is part of an ongoing investigation of the Arrow Canyon invertebrate fauna being conducted at the University of Illinois. Materials under study include about 1,000 weathered-free specimens, and silicified material etched from about 500 pounds of matrix. Twenty-eight taxa have been iden ified, most notably a new species of Brasilioproductus Mendes, a genus previously known only from the Amazon basin. Ranges of Spiriferellina ceres, Antiquatonia hermosana, Neochonetes dominus, Cleiothyridina milleri, and Rhipidomella elyensis are here extended into the late "Atokan." Composita trinuclea, characteristically Mississippian, also occurs. Biostratigraphic correlation with both the southern Rocky Mountain region and Ohio is strong. Midcontinental correlations are less firm, probably because Atokan rocks in that area are poorly fossiliferous.
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