Trilobites from the Crepicephalus Zone (upper Guzhangian Stage, Miaolingian Series, Cambrian) from northern Sonora, Mexico, and its correlation to Arizona and Texas, USA

Abstract

In the Cananea region, northeastern Sonora, there is a sedimentary sequence of the lower Paleozoic outcrops that includes the Cambrian Bolsa Quartzite and Abrigo Formation. This work describes and illustrates the upper middle Cambrian ptychopariid trilobite fauna from the Abrigo Formation for the first time for Mexico. Trilobites from the inner shelf deposits of the El Tule and Mesteña hills include Crepicephalus sp., Tricrepicephalus texanus, Llanoaspis modesta?, Coosella perplexa, Coosia ariston, and Coosia sp., which represent the Crepicephalus Zone (upper Guzhangian Stage, Miaolingian Series). The distribution of these species denotes a strong affinity with North American fauna, specifically with Arizona and Texas.