Trilobites of the Upper Cambrian Ptychaspid Biomere, Wilberns Formation, Central Texas
Trilobites collected during the past 20 years from the Morgan Creek, Point Peak, and San Saba Members of the Wilberns Formation comprise 89 species assigned to 45 genera belonging to zones of the upper Franconian and Trempealeauan Stages of the Upper Cambrian Croixan Series. New zonal names are proposed in the interest of a regionally applicable nomenclature. Although none of the zonal nomenclature is identical to that of the 1944 Cambrian Correlation Chart of Howell et al., the four zones recognized in centralTexas are equivalent to the eight highest zones on the Chart.
Longacre, S. A., 1970, Trilobites of the Upper Cambrian Ptychaspid Biomere, Wilberns Formation, Central Texas: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 66, 70 p.
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The University of Texas at Austin, Bureau of Economic Geology
Report of Investigation