A COMPARATIVE STUDY OF DIVERSITY AND ORGANISMAL INTERACTIONS AT THE FALLS OF THE OHIO (MIDDLE DEVONIAN, CLARKSVILLE, INDIANA) TO SIMILAR ENVIRONMENTS WITHIN THE KASKASKIA SEA

During the Middle Devonian, the Kaskaskia Sea was transgressing over much of what is now eastern North America. Many biostromes and reef-like environments have been studied within this region, including the those present at the Falls of the Ohio State Park in Clarksville, Indiana. The fossil beds at this locality are made up of the Coral Zone of the Jeffersonville Limestone, which is composed of abundant rugose and tabulate corals and stromatoporoid sponges. Unlike other biostromes within the Kaskaskia Sea, the Falls of the Ohio contains few organisms besides these corals and sponges. Despite exceptional preservation, the only organismal interactions/associations observed in the Coral Zone are between corals and stromatoporoids (i.e., no observed bioerosion or encrustation). To discover why the Coral Zone shows little diversity in non-coral/stromatoporoid taxa and very few types of interactions between organisms, this study will present a comparison between similar paleoenvironments throughout the Kaskaskia Sea.

From August-October of 2017, data were collected at the Falls of the Ohio by transect sampling. Corals were first identified to the genus-level, then measured for length, width, and compass bearing. In addition to size measurements, faunal associations were noted and described. Stromatoporoids represented 73% of the total biomass, followed by rugose corals at 18% and tabulate corals at 9%. Of the 170 stromatoporoid individuals assessed in this study, 30 had definitive interactions with coral fauna, making these types of occurrences fairly common at the Falls of the Ohio, however no other types of associations were observed.

In order to compare the Falls of the Ohio with similar ecosystems throughout the Kaskaskia Sea, a database of like-environment fossil localities was assembled using the Paleobiology Database and literature review. For each location, information was gathered on paleoenvironment (e.g., water depth, energy, substrate), taxon diversity, and categories of organismal interactions, if present. Comparing the Falls of the Ohio to similar environments within the same seaway may provide insight into whether the Falls of the Ohio exhibits atypical biostrome structure and associations during the Middle Devonian.