A DIVERSE CHONDRICHTHYAN FAUNA FROM THE KANSAS CITY GROUP (PENNSYLVANIAN) OF MISSOURI

Pennsylvanian chondrichthyan remains are understudied, especially as microfossils, and undervalued as indicators of depositional environments. This analysis studies portions of the Kansas City Group (Missourian Stage; Late Pennsylvanian). The Iola Limestone, Liberty Memorial Shale and Wyandotte Limestone were sampled, processed, and sieved to reveal not only the typical macroinvertebrates and conodonts but also a diverse chondrichthyan assemblage, typically ignored or unknown to many geologists. The shark remains typically indicate normal, open marine conditions but a few environments were indicated. Shark remains can be categorized as teeth, dermal denticles, mucous denticles, fin spines, and cephalic hooks. Teeth are rare compared to denticles but denticles have been identified primarily as form taxa due to their abundance, however, they are rarely found intact on a specimen. Denticles come in assorted styles that could be derived from the same shark species, varying according to location on the body, as in extant sharks. The most common elasmobranch remains are from symmoriid sharks, including: teeth from at least two species of Stethacanthus, as well as Cobelodus; brush-apex and cranial cap denticles from Stethacanthus; and symmoriid mucous membrane denticles. Ctenacanthid sharks are represented by Glikmanius occidentalis and Zangerlodus type teeth and fin-spine fragments. Dermal denticles of the form genera Sturgeonella; Cooperella; Kirkella; and Moreyella are also common. Less common remains include the teeth and cephalic hooks of hybodont sharks; several types of petalodont teeth, Protacrodus teeth; teeth and branchial denticles from the marine xenacanthid Bransonella and teeth from the neoselachian genus Cooleyella. Compound dermal denticles similar to Nebraskella ossiani are interpreted to be the remains of cochliodont holocephalans. Denticles of the eugeneodontid Listracanthus are rare, found primarily in core shales, and are the only fish remains found in the Muncie Creek Shale Member of the Iola Limestone at this location. Correlations of shark remains with conodonts are consistent with Listracanthus occupying deep water environments and Cobelodus seems to have preferred open ocean continental shelf environments, compared to the more cosmopolitan Stethacanthus.