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 faunal associate, was not observed, because its habitat is probably far offshore from those in which Morgan limestones were deposited. Even at the generic level, Pennsylvanian conodonts are environmentally sensitive; hence, they are useful for both sedimentologists and paleontologists. Sedimentologists can use conodont distributional data as an independent test of their paleoenvironmental interpretations. Paleontologists can identify conodonts that are strongly facies-dependent, and differentiate conodonts best suited for biostratigraphy.