FIGURE 1 in The pliomerid trilobite Ibexaspis and related new genera, with species from the Early Ordovician (Floian; Tulean, Blackhillsian) of the Great Basin, western USA

FIGURE 1. Schematic diagram of stratigraphic distribution of species of Ibexaspis, Deltapliomera, Tuleaspis, and Millardaspis in Floian (Tulean–Blackhillsian) sections of the Yellow Hill Limestone in eastern Nevada (Section YH), Fillmore Formation and Wah Wah Formation in western Utah (Sections G, H, J), and the Garden City Formation in southeastern Idaho (Sections HC5, HC6). Measurements are in metres. Metreages are not to scale. The zonation is that established by Adrain et al. (2009), with additions and modifications by McAdams and Adrain (2010, 2011a, 2011b), Adrain and McAdams (2012), and herein (see text).