The youngest Ordovician (latest Katian) coral fauna from eastern Australia, in the uppermost Malachis Hill Formation of central New South Wales

Abstract

Corals representing the sole occurrence of C/S Fauna IV of the regional biostratigraphic scheme occur in limestone in the uppermost Malachis Hill Formation of the Bowan Park area, central New South Wales. New species described and illustrated from this fauna include the rugosan Bowanophyllum ramosum and tabulate Hemiagetiolites longiseptatus. Also documented are three other distinct species of Hemiagetiolites, H. spinimarginatus (Hall, 1975), H. sp. cf. H. palaeofavositoides (Lin & Chow, 1977) and H. sp., an unnamed species of Paleofavosites, and three heliolitine corals, Heliolites waicunensis Lin & Chow, 1977, Navoites cargoensis (Hill, 1957) and Plasmoporella sp. These descriptions, which complete knowledge of the entire fauna collected over 50 years, enable interesting conclusions to be drawn regarding palaeogeographic affinities of this youngest in situ Ordovician coral fauna known from eastern Australia. Its remarkable similarities to contemporaneous coral faunas from South Tien Shan and the Chu-Ili Terrane indicate strong connections between eastern Australia and the latter two terranes, supporting their positioning in equatorial latitudes of eastern peri-Gondwana. However, it is puzzling that fewer similarities exist between the eastern Australian coral fauna and those from rocks of Katian age in SE China, which may be due to either a slightly younger age of the former fauna or a relatively higher palaeolatitudinal position of South China.Guangxu Wang [gxwang@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing Institute of Geology and Palaeontology, Nanjing 210008, China; Ian G. Percival [ian.percival@planning.nsw.gov.au], and Yong Yi Zhen [yong-yi.zhen@planning.nsw.gov.au], Geological Survey of New South Wales, 947–953 Londonderry Road, Londonderry, NSW 2753, Australia.