A quantitative analysis of conodont distributional patterns in the Middle Pennsylvanian (Atokan and Desmoinesian) Morgan Formation of northeastern Utah and northwestern Colorado supports previous empirically derived Pennsylvanian conodont biofacies models. R-mode factor analysis and stepwise discriminant analysis both demonstrate strong facies-dependence for the platform conodonts Adetognathus and Idiognathodus. The Adetognathus biofacies, which may also include Hindeodus and Diplognathodus, characterizes nearshore marine deposits in which salinity and/or temperature fluctuated considerably. The Idiognathodus biofacies, which also includes Neognathodus, characterizes slightly offshore, normal-marine deposits. The environmental significance of Idioprioniodus is uncertain because of its sporadic distribution; Gondolella, its normal...