Age of the Middlesex Shale (Upper Devonian, Frasnian) in New York State

The Middlesex Shale, the basal black shale in the Sonyea Group, represents the first major Frasnian sea level rise and redevelopment of an extensive anoxic substrate in the Appalachian Basin. The last occurrence of Ancyrodella alata and Ad. rugosa just below the base of the Middlesex in the West River Shale, and the appearance of Ad. gigas. Ancyrognathus? aff. Ag. ancyrognathoideus, and Palmatolepis punctata in, or just above the Middlesex indicate an assignment very near or at the start of Montagne Noire Zone 5 (punctata Zone).