Very well preserved Lower Ordovician graptolites are found in the Ibex region of Millard County, Utah. They are preserved in the shale that is interbedded with limestone of the Pogonip Group throughout much of its 1,000+-m thickness. The graptolites are an important element of a shaly fauna that interbeds uniquely with an extensive, well-developed shelly fauna.
In this region, 45 species from 13 genera are recognized. Of these, 15 are new and are described and named; 26 were collected in great enough numbers to be accurately identified and statistically analyzed, and 12 have excellently preserved ontogenetic and (or) early astogenetic developmental stages, descriptions of which add considerably to our present knowledge of graptolites of Early Ordovician age.
Seven graptolite zones are established for biostratigraphic correlation. The zones are the first to be established in the Great Basin of the western United States. These zones will serve as a much-needed reference for correlation of strata within and possibly beyond this region.