Bryozoans are abundant and diverse in the upper part of the Chainman Shale (Mississippian; Osagean, Meramecian-Chesterian) and in the upper Chesterian part of the overlying Ely Limestone (Mississippian-Pennsylvanian) in the Confusion Range of western Utah. The bryozoan assemblage includes 15 genera and 18 species; 12 species are new and 6 are in open nomenclature. The new species are the trepostomes Callocladia jensensis, Stenopora confusionensis, Stenoporella mineriensis, Tabulipora atacta, T. ricta, T. sarcinula, T. stragula, the cryptostomes Ascopora macellata, Rhabdomeson artum, Streblotrypa angulatum, Strebloplax pertusa, and the cystoporate Cystodictya astrepta. Species in open nomenclature are the trepostome Anisotrypa sp., the cryptostomes Saffordotaxis sp., Archimedes sp., Fenestella sp., Penniretepora sp. A, and Polypora sp. Callocladia and Strebloplax are known only from Chesterian strata in North America; Strebloplax is known only from the conterminous United States. The stratigraphic range of Stenoporella, also known only from the United States, is extended into rocks of supposed Pennsylvanian age. Stenoporella mineriensis, the only species in this bryozoan assemblage known to occur outside Utah, is also found in the Ely Limestone (Pennsylvanian) of Nevada.

Tabulipora is the dominant genus in the Chesterian rocks of this region; T. sarcinula and T. ricta are the most abundant taxa. The shallowing of the marine environment and the establishment of carbonate deposition during late Chainman time permitted widespread development and dispersal of the bryozoan faunas in western Utah.