FLOIAN (EARLY ORDOVICIAN) CHITINOZOANSFROM SOUTH CHINA

Chitinozoans were recovered from graptolitic shales of Floian (Early Ordovician) age in the Nanba Section of the Yiyang area in Hunan Province, South China. The chitinozoan association includes four genera and six species. They are: Euconochitina symmetrica (Taugourdeau and de Jekhowsky, 1960), Clavachitian langei (Combaz and Péniguel, 1972), Lagenochitna ventriosa (Achab, 1980), Conochitina pseudocarinata Paris, 1981，Conochitina decipiens Taugourdeau and de Jekhowsky, 1960 and Conochitina poumoti Combaz and Peniguel, 1972. The chitinozoans were recovered from four graptolite biozones which are, in ascending stratigraphic order, the Tetragraptus approximatus, Pendeograptus fruticosus, Didymograptellus bifidus, and Corymbograptus deflexus biozones.These graptolite biozones provide independent stratigraphic control for the chitinozoans. The chitinozoan assemblage is characterized by species that have a glabrous vesicle wall and do not show obvious differentiation in their chamber and neck. This is the first report of Floian chitinozoans from the Jiangnan Slope Region, and the overall composition of the chitinozoan assemblage resembles coevel assemblages from various sections previously reported in the Yangtze Region, South China. Together with coexisting graptolites, these chitinozoans can be used for precise correlation at both a regional and global scale.