A UNIQUE OCCURRENCE OF SPINIPLATYCERAS AND ATRYPA ‘RETICULARIS’ IN THE ONONDAGA LIMESTONE, HUDSON VALLEY, NEW YORK

The (Eifelian) Onondaga Limestone crops out in the Hudson Valley from Albany, south to Kingston and then southwest to Port Jervis along Route 209. The formation consists of four members, three of which are exposed in the study area: Edgecliff, Nedrow, and Moorehouse. An association of Spiniplatyceras and Atrypa ‘reticularis’ occurs within the Atrypa-Coelospira-Nucleospira Community (AMNH Loc. 3135) near the top of the Moorehouse Member near Leeds, and again near Saugerties, New York. The association serves as a marker horizon for the top of the Moorehouse. The occurrence of current-swept clusters of atrypids and the spiny gastropods may have been due to selective preservational factors or ecological ones. Additional faunal constituents include tabulate and rugosan corals, trilobites and numerous brachiopods. The spinose gastropod genus Spiniplatyceras Blodgett and Frýda, 1999 is recognized only in strata of Pragian-Givetian age, and is biogeographically significant in that is primarily found in the Eastern Americas Realm (EAR) in eastern North America from Pragian-Givetian time, as well as in the Great Basin of western North America during the Pragian-early Emsian when it comprised a western extension of the EAR, as well as in several rare taxonomic outliers within the Old World Realm of Germany during the late Early Devonian-Eifelian. Although spinose members of the platyceratids have been reported since Conrad (1840), these specimens have the best-preserved spines known from the Devonian of New York where they were first documented.