Trilobites of the Upper Cambrian Ptychaspid biomere, Wilberns formation, central Texas

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Longacre, Susan Ann

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University of Texas at Austin. Bureau of Economic Geology


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 central Texas are equivalent to the eight highest zones on the Chart.


To obtain a print version of this publication visit: and search for: RI0066. Reprint of Memoir 4, The Paleontological Society, supplement to Journal of Paleontology, v.44, no.1, January 1970.

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