Lower middle ordovician chitinozoa from the southern Appalachians, United States

To assess the occurrence and significance of chitinozoans in the lower Middle Ordovician of the Southern Appalachians, 212 samples from eleven sections were selected for study. About 50% of the samples yielded chitinozoans but only half the productive samples contained reasonably abundant and taxonomically varied assemblages. Virtually all of these samples originate from the Lenoir Limestone in the Blount Con-facies Belt, but the Chickamauga Limestone of Alabama has also produced some interesting chitinozoans. A total of nineteen species have been identified, one new (Fungochitina chickamaugensis n. sp.). As a whole, the chitinozoan assemblages show close similarity to those of Baltoscandia, about 85% of our species being known from that area. They are less similar to assemblages from Britain, southwestern Europe, and other parts of North America. Although many species are long-ranging, some with limited vertical range are useful biostratigraphically and suggest correlations in general agreement with those indicated by conodonts and other fossils. Appalachian chitinozoan taxa exhibit complex variations in frequency and geographic distribution but ecologic factors controlling those patterns are unclear. Few chitinozoans were found in basinal rocks and intertidal and supratidal strata are also virtually barren. The richest collections are from rocks representing relatively shallow depositional environments, partly of lagoonal character. The present study shows that chitinozoans are widespread but not abundant in the strata studied and that they have considerable potential as index fossils in the Southern Appalachians.