PALEOECOLOGICAL AND STATISTICAL ANALYSIS OF A NEW OPHIUROID (ECHINODERMATA) FROM UPPER MISSISSIPPIAN (CHESTERIAN) SLADE FORMATION OF NORTHEASTERN KENTUCKY

Schoenaster carterensis, n. sp., is a new encrinasterid ophiuroid (Echinodermata) from Upper Mississippian (Chesterian) shallow-water carbonates in the Ramey Creek Member of the Slade Formation in northeastern Kentucky. First described in the 1860s from Lower and Middle Mississippian rocks, Schoenaster is not a well-known genus, but the 39 specimens in this collection permit further definition of the genus and extend its range. The number of specimens also permit differentiation of life stages based on average arm length and show that arm length, disc perimeter and disc area are interrelated in statistically significant ways. Though replaced by chert, the specimens are nearly intact due to rapid burial as rare constituents in habitat communities distributed among four, once contiguous habitats, including shoal, shoal margin, transitional and basinal. Most of the ophiuroids were concentrated on firmgrounds or hardgrounds in shoal and transitional environments, concentrations that probably reflect substrate stability and ability to support the ophiuroids’ generalist feeding strategy. Many ophiuroid species are known from only a few specimens, severely limiting interpretations about their detailed taxonomy, individual variation, and ecology. In contrast, the greater number of specimens and extensive knowledge of their geologic occurrence in this study permit detailed interpretations regarding the taxonomic, intraspecific and ecologic attributes of this species, and perhaps other fossil ophiuroids.