The Mississippian (Late Tournaisian) ammonoid Rotopericyclus from the Borden Formation, Kentucky

The Mississippian ammonoid Rotopericyclus TURNER, 1948 is reported from the Nancy Member of the Borden Formation near Morehead in northeastern Kentucky. This is the first confirmed record of the genus in North America. The ammonoids Rotopericyclus howardi n. sp. and R. chaplini n. sp. are associated with conodonts, including Polygnathus communis carina HASS, 1959 and Pseudopolygnathus multistriatus MEHL & THOMAS, 1947, that indicate an early Osagean (Fern Glen or lower Burlington [Dolbee Creek Member] equivalent) age corresponding to the early Ivorian Substage of the Belgian Late Tournaisian succession.