Two Cambrian agnostoid trilobites,Agnostotes orientalis (Kobayashi, 1935) andLotagnostus americanus (Billings, 1860): Key species for defining global stages of the Cambrian System

摘要

The systematics, stratigraphic distribution and geographic distribution of two widely distributed agnostoid species from the Furongian Series of the Cambrian are reviewed. The speciesAgnostotes orientalis (Kobayashi, 1935) andLotagnostus americanus (Billings, 1860) have been described from around the world under a variety of species and subspecies names, and have been assigned to a variety of genera. Nomenclatural problems have hindered to some extent a full under standing of the value of these two forms for intercontinental correlation. Both species have relatively narrow stratigraphic ranges and intercontinental distributions in open-shelf lithofacies. These conditions make these species excellent candidates for defining the bases of stage boundaries within the Furongian Series.