Potsdam Sandstone Trilobites

The Potsdam Sandstone is composed of the lower Ausable and upper Keesville members.  The Ausable member is estimated to be Middle Cambrian in age based on a) the presence of Middle Cambrian trilobites in the underlying Altona Formation and b) the conformable nature of the Altona Formation with the Ausable Member.  The Keesville is dated as Late Cambrian based on a Crepicephalus Zone fauna.  This fauna was first reported by Walcott in 1912, but has never been thoroughly studied.  I am in the process of describing and revising the phylogenies of some of those species.  At least one genus is new and many of the species have never been described.

Pemphigaspis Potsdam Trilobite