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.

The type area for the Springerian stratigraphic sequence is in southern Oklahoma (Carter County) and that of the Morrowan is in northwestern Arkansas (Washington County). In the past, both series have been employed as comprising successive time-stratigraphic serial subdivisions of the North American Lower Pennsylvanian. A conodont zonal scheme developed herein provides a means for correlations between both type sections and demonstrates that the Springerian overlaps with the underlying Chesterian and overlying Morrowan. Therefore, usage of the Springerian as a viable subdivision of the Lower Pennsylvanian should be discontinued. In the type Springerian, the upper part of the Goddard Formation and Rod Club Member of the Springer Formation correlate with the Menard through the Grove Church sequence in the Illinois Basin. The “B” Shale Member contains an undiagnostic Upper Mississippian fauna, and the Target Limestone Lentil of the Lake Ardmore Member contains conodonts that correlate with the Cane Hill Member of the Hale Formation of the type Morrowan. The Lake Ardmore through Primrose sequence correlates with the Hale through Woolsey Member of the Bloyd Formation in Arkansas. The Dye Shale and Kessler Members of the Bloyd contain two upper Morrowan conodont zones, and the position of the Trace Creek Shale Member with respect to the Morrowan-Derryan (=Atokan) Boundary cannot be precisely determined. Morrowan conodont collections from northeastern Oklahoma can be correlated with the type Morrowan zonal scheme. The zonal scheme developed in both areas is present in Morrowan rocks in west Texas and Nevada. One taxon is newly described.