ARCHAEOCYATHS FROM YORKE PENINSULA, SOUTH-AUSTRALIA AND ARCHAEOCYATHAN EARLY CAMBRIAN ZONATION

Two assemblages of archaeocyaths are documented from Lower Cambrian ou tcrops and drillholes on Yorke Peninsula, South Australia. The older a ssemblage (11 species) occurs in the uppermost Kulpara Formation and c onformably overlying basal Parara Limestone. and is equivalent to Lowe r Faunal Assemblage II in the Flinders Ranges. The younger assemblage (28 species plus Acanthinocyathus and Radiocyathus) occurs in the Kool ywurtie Member near the top of the Parara Limestone. Equivalent taxa a re widespread in the Flinders Ranges, western New South Wales and Anta rctica. Archaeocyathan distribution is now sufficiently well known to propose three assemblage zones and two informal assemblages for region al correlation. No new taxa have been added, but Erugatocyathus scutat us (Hill) and Pycnoidocyathus latiloculatus (Hill), hitherto known onl y from Antarctica, are found in the upper assemblage on Yorke Peninsul a. Irregular archaeocyathan systematics are discussed, the ontogeny of Archaeopharetra irregularis (Taylor) clarified, and Kruseicnema Debre nne, Gravestock & Zhuravlev, represented by K. gracilis (Gordon), is f ully described.