Archaeocyaths from Yorke Peninsula,South Australia and archaeocyathan Early Cambrian zonation

Zhuravlev, A. Yu., & Gravestock, D. I., 1994:03:28. Archaeayaths from Yorke Peninsula, South Australia and archaeocyathan Early Cambrian zonation. Alcheringa 18, 1–54. ISSN 0311-5518.

Two assemblages of archaeocyaths are documented from Lower Cambrian outcrops and drillholes on Yorke Peninsula. South Australia. The older assemblage (11 species) occurs in the uppermost Kulpara Formation and conformably overlying basal Parara Limestone, and is equivalent to Lower Faunal Assemblage II in the Flinders Ranges. The younger assemblage (28 species plus Acanthhcyathus and Rodiocyathus) occurs in the Koolywurtie Member near the top of the Parara Limestone. Equivalent taxa are widespread in the Flinders Ranges, western New South Wales and Antarctica. Archaeocyathan distribution is now sufficiently well known to propose three assemblage zones and two informal assemblages for regional correlation. No new taxa have been added, but Erugatocyathus scutatus (Hill) and Pycnoidocyathus latiloculatus (Hill), hitherto known only from Antarctica, are found in the upper assemblage on Yorke Peninsula. Irregular archaeocyathan systematics are discussed, the ontogeny of Archaeopharetra irregularis (Tylor) clarified, and Kruseicnema Debrenne. Gravestock & Zhuravlev, represented by K. gracilis (Gordon), is fully described.     

Early Cambrian endolithic algae

Phosphate fillings of the tunnels made by endolithic micro-organisms in the shells of Early Cambrian molluscs have been observed on phosphatic internal moulds at several sites. The best preserved examples are from the shells of the gastropod Yuwenia bentleyi from the Parara Limestone of South Australia. Three distinct types of borings are found in these shells: long unbranched tunnels that are either about 10 µm or 3 µm in diameter, and short vertical holes. The nature and distribution of the borings suggest that they were made by photosynthetic algae rather than fungi.     

An Asian compound archaeocyath

Material from the Jindingshan Formation (Tsanglangpu stage) at Jindingshan, Guizhou province, China, confirms that Agastrocyathus grandis Yuan & Zhang is a massive compound archaeocyath with chaetetide architecture. A new genus Zunyicyathus includes this species and Z. pianovskajae from Central Asia.