A CLOSE EXAMINATION OF EARLY OLIGOCENE (RUPELIAN) MARINE MICROFOSSILS FROM THE ASHLEY FORMATION OF SOUTH CAROLINA

Global marine deposits from the Oligocene epoch are some of the least studied units from the latter half of the Cenozoic Era. This paucity is primarily due to a lower number of accessible Oligocene marine rock units compared to Miocene, Pliocene, and Pleistocene exposures. The Lowcountry of South Carolina contains three Oligocene units, two of which are highly fossiliferous: the Chattian Chandler Bridge Formation and the Rupelian Ashley Formation (28 Ma). The earth underwent multiple global cooling events during the Eocene-Oligocene Transition (EOT) with the formation of the Antarctic Circumpolar Current and the opening of the Drake Passage. The EOT extinction event impacted both marine and terrestrial faunas, with our oceans further witnessing a change in chondrichthyan populations as they shifted from lamniform-dominant to carcharhiniform-dominant species. Few studies have intensively sampled microfossils within the Rupelian Ashley Formation, which preserves a wide range of ichthyofauna. Through surface collection and bulk sampling of dredged gravel, this study reports on preliminary findings from the Ashley Fm including over 50 taxa of cartilaginous and bony fish, echinoderms, mollusks, crustaceans, and foraminifera. Notable findings from our assemblage include specimens of Pristiophorus, Rhincodon, Galeorhinus, Paragaleus, cf. Physogaleus secundus, Stomatopoda indet., Conosaurus, Ginglymostomatidae, and ophiuroid remains.