Cirripedes (Crustacea) from the Pliocene (Piacenzian) Rushmere Member, Yorktown Formation of North Carolina, USA

Abstract

Abundant cirripedes of Pliocene age (Piacenzian Stage) are described from two localities in North Carolina. These include seven species, of which the most abundant are the large balanids Arossia glyptopoma (Pilsbry, 1916), previously known from the Pliocene of Florida and Virginia, and Chesaconcavus proteus (Conrad, 1834), known from the Pliocene of Virginia and Florida. Abundant material of the scalpellid Scalpellum multangulatum (Lea, 1843) permits the first description of all the plates of this species and allows a reconstruction to be made. A new species of Membranobalanus Hoek, 1913, M. distortus sp. nov., a genus which has an obligate relationship with clionaid sponges, represents only the second fossil record of this extant genus. New records of the extinct whale barnacle Coronula bifida Bronn, 1931 are the first from the Atlantic Coastal Plain of the eastern USA and indicate that the migration paths of humpback whales in the Pliocene ran close to the palaeocoastline. The material includes the only known juvenile specimens of the species and allows reconstruction of the ontogeny of C. bifida. We report the second and third North American occurrences of the verrucid barnacle Verruca stroemia (O.F. Müller, 1778) and the second known record of Fistulobalanus multiseptatus (Ross, 1964). The barnacle assemblage represents a warm water fauna, brought into the region during the Mid-Piacenzian Warm Period by the basal Rushmere Member transgression at 3.25 Ma. Only 1 of the 7 species recorded is still extant.