Cambrian to Permian conodont biogeography in East Asia-Australasia

Conodont faunas of the allochthonous East Asian terranes demonstrate biogeographic affinities with Australasia during the Cambrian to Permian and suggest close proximity or attachment to Australian Gondwanaland in the Palaeozoic over a time frame of about 250 My, from about 500 Ma in the Late Cambrian to the end of the Permian at about 253 Ma. Lower Palaeozoic conodonts that define an East Asia-Australasia province include the Late Cambrian genus Eodentatus and Ordovician taxa such as Serratognathus spp., Aurilobodus spp., Plectodina onychodonta and Tasmanognathus. The distinctive Lower to Middle Silurian conodont genera Tuberocostadontus and Nericodus are also restricted to East Asia and Australasia. Devonian conodont faunas appear to be more cosmopolitan, which may be related to global oceanic current distribution patterns. At the same time endemic forms are common, but species restricted to East Asia - Australasia have not been widely recognised. Lower Carboniferous conodont faunas of the Asian terranes and Western Australia are generally cosmopolitan. However, the distribution of Mestognathus beckmanni appears restricted to Gondwanaland (including the Sibumasu terrane), and Laurentia (including the allochthonous terranes of N. America). Eastern Australian conodont faunas are highly endemic during the Visean and are dominated by the genus Montognathus, which has also recently been discovered on the Sibumasu terrane. Conodonts appear to be absent from the Permian of eastern Australia due to the cold conditions present there as a result of high latitudinal position and Carbo-Permian glaciation. Conodonts were also thought, until recently, to be absent from Western Australia due to cold climatic conditions. However, scarce low diversity conodont faunas are now known from Western Australia and these are characterized and dominated by the cold-water tolerant genus Vjalo-vognathus which invaded the shallow continental margin seas of Gondwanaland during periods of climatic amelioration. Vjalovognathus is also recorded from Timor and the Pamirs and defines a Tethyan-Gondwanaland conodont province during the Permian.