CEPHALOPOD DIVERSITY IN THE LOWER DEVONIAN SCHOHARIE FORMATION: A UNIQUE OPPORTUNITY FOR REASSESSMENT OF DIVERSITY FROM GLACIAL ERRATICS

Large numbers (>100) of glacial erratics belonging to the Rickard Hill Facies of the Saugerties Mbr. of the Schoharie Fm. (Lower Devonian, Tristates Group) occur scattered across High Mountain, Passaic County, New Jersey. These erratics are most similar to lithologies exposed ~150km north in the Helderberg region of NY. The Rickard Hill Facies erratics contain an assemblage of exceptionally well-preserved cephalopods, dominated by orthoconic nautiliods, exposed by a complex sequence of physical and chemical weathering during glacial erosion, transportation and deposition. Phragmocones and body chambers display preferred orientations on bedding surfaces and contain casts and molds of numerous invertebrates including trilobites, crinoids, brachiopods and corals. Original taphonomic conditions indicate that the High Mountain cephalopods represent a post-mortem assemblage transported by wave and current activity prior to final burial and fossilization. In initial description of the cephalopod fauna of the Schoharie Fm. in the Helderberg region, James Hall identified >65 species from the ~2m thick unit. Our examination of >85 specimens from the High Mountain erratics suggest a total of 12-15 species present. The unique state of preservation of the High Mountain orthoconic nautiliods provides an opportunity to reassess earlier taxonomic assignments as well as reconstruct additional elements of the complex surficial geology of the New Jersey Piedmont and High Mountain.