ENVIRONMENTAL AND ECOLOGICAL ANALYZATION OF MIDDLE CHESTERIAN CRINOIDS

The Mississippian Period was a peak of crinoid diversity during the Paleozoic, with genera radiating into new environmental niches. Eucladid crinoids expanded during this time and diverged into many specialized morphs adapted to varying water turbidities and tiering levels. An outcrop near Princeton, Kentucky has yielded abundant articulated and semi-articulated crinoid specimens collected over many years as they weathered out of the Middle Chesterian Glen Dean Formation. Using systematic taxonomy, six crinoid species have been tentatively identified: Dasciocrinus florialis (Yandell and Shumard), Phacelocrinus decabrachiatus (Hall), Phacelocrinus longidactylus (McChesney), Phacelocrinus sp., Phanocrinus maniformis (Yandell and Shumard), and Zeacrinites sp. Other noticeable fauna includes blastoids, brachiopods, and fenestrated bryozoa. The morphologies of these crinoids have been used to reconstruct possible relationships between members of the benthic community in this filter-feeder dominated Mississippian ecosystem. Specifically, traits such as fan density and branching patterns were analyzed to determine the most probable environments, tiering, and optimal turbidity for individual species and the collective faunal community. This kind of study shows the benefits of using biological traits as evidence for environmental and ecological conclusions when outcrops have been extremely weathered and degraded.