Vertebrate Assemblages of the Skelley Limestone (Conemaugh Group: Carboniferous, Gzhelian) in Noble and Muskingum Counties, Ohio

Three outcrops of the Gzhelian-aged Skelley Limestone (Casselman Formation, Conemaugh Group) were explored for vertebrate macrofossils and vertebrate microremains. The purpose of this exploration was to construct a better ecological history of the marine communities in the Late Pennsylvanian of eastern Ohio. Bulk limestone samples were collected, washed with acid, sieved and the resulting residues produced 21 distinct taxa of near-shore marine vertebrates. Osteichthyans were represented by an unknown palaeonisciform, an unknown platysomid, and an unknown palaeoniscoid. Holocephalians were represented by symmoriforms, helodontiforms, cochliodontiforms, and petalodontiforms. Elasmobranch groups included ctenacanthiforms and euselachians which contained representatives of hybodontiforms, protacrodontiforms, and neoselachians. All osteichthyan taxa are reported from the Skelley Limestone for the first time. Furthermore, three chondrichthyan genera, Ossianodus, Diablodontus, and Adamantina, represent significant extensions to the temporal or geographic distributions of these genera. While the few previous studies on the fauna of the Conemaugh Group have indicated that the marine units within were fairly biodiverse overall, these studies focused primarily on invertebrates or only specific groups of vertebrates. Significantly less work has been done towards overall analyses of the vertebrate fauna of the constituent cyclothems of the Conemaugh Group. This examination of the Skelley Limestone shows that marine vertebrate biodiversity at the end of the Conemaugh Group, and by extension the Pennsylvanian, remained high. Further analysis of the Skelley Limestone, along with similar explorations of other stratigraphic units with the Conemaugh Group, may generate further revelations in the paleobiogeography, biostratigraphy, and evolutionary history of a number of Paleozoic marine vertebrates.