FOSSIL CORALS FROM THE LOWER–UPPER MIOCENE FROM ATLANTIC DEPOSITS IN DELAWARE AND FLORIDA, USA

The Miocene corals of the North American Atlantic coast have been explored thus far only at select sites, and species identifications are still unknown in certain areas. Herein we compare corals from a well-known lower Miocene site, the Chipola Formation, exposed in northern Florida to the lesser known corals of the St. Marys Formation, exposed in Virginia, Maryland, and Delaware.

Fossil corals from this time and region are housed at the Virginia Museum of Natural History, including scleractinians from two different formations (n = 103). The Chipola Formation is represented by material collected from the McClellan Farm locality in the panhandle of Florida (n = 75). The Chipola is a fossiliferous limestone with intermittent clays. Other fossils from this site include abundant mollusks, echinoderms, and bryozoans. The site chosen for the St. Marys Formation is located in Smyrna, Delaware, representing the top of the Chesapeake Group (n = 28). This formation is also fossiliferous limestone with abundant mollusks, corals, and bryozoans.

Despite a temporal separation of at least four million years, there are strong similarities between the sites. The most abundant coral species at both sites is Flabellum chipolanum, a stationary epifaunal suspension feeder. The second most common coral is Proties sp., an epifaunal micro-carnivorous phytosymbiotic stony coral. Both Proties and F. chipolanum are typically abundant in areas considered as having been tropical. The third most common coral identified was Stylophora imperatoris, a stationary intermediate-level epifaunal micro-carnivorous photosymbiotic species.

Future studies connecting these coral collections to other assemblages in the Atlantic Coast will help further clarify the diversity and relative abundances of coral species during the changing climates of the Miocene in North America.