NEW PERMIAN COLD WATER CONODONT FAUNAS FROM THE TETHYAN GONDWANAN MARGIN OF AUSTRALIA

Conodont faunas have now been recovered from Permian sediments in the Perth, Carnarvon, and Canning basins of Australia, and from the adjacent island of Timor, on what was the western (Tethyan) margin of Gondwanaland. Specimens are rare and diversity low, with the cold water tolerant genera Vjalovognathus and Hindeodus being most common. These faunas range in age from the Sakmarian to the Wuchiapingian, and can, in part, be correlated with other Tethyan faunas found in the Salt Range (Pakistan), the Pamirs (Tajikistan) and the Himalaya (central Nepal).

Faunal diversity appears to suggest a north-south gradient with fewer species at higher latitudes and diversity increasing northward. Only one species has been recovered from the Perth Basin in the south, but up to 4 species have been recorded from Timor in the north. Species diversity in the Pamirs may be as high as 8 to 10 species. This trend is presumed to reflect a temperature gradient, with water temperatures increasing northward.

The oldest fauna, consisting of Vjalovognathus australis and Hindeodus sp., has been found in the Callytharra Formation in the Carnarvon Basin, the Nura Nura Member of the Poole Sandstone in the Canning Basin and from Timor. The fauna appears to be found from the late Sakmarian into the early Artinskian. The next fauna contains Vjalovognathus shindyensis and one or more species of Mesogondolella and Hindeodus. This second fauna is thought to be of predominately of Kungurian age. The third fauna is known only from a single species of Vjalovognathus, V. sp. A, which is endemic to Australia. This fauna had been recorded from the Beekeeper Formation in the Perth Basin, the Wandagee Formation and Coolkilya Siltstone in the Carnarvon Basin and the Lightjack Formation in the Canning Basin. Based on associated macrofauna, this fauna is of late Kungurian to Rhodian age, and could be as young as Wordian. The youngest fauna consists only of Vjalovognathus sp. B and is found only in the Cherrabun Member of the Hardman Formation in the Canning Basin. This fauna is believed to be of Wuchiapingian age and to correlate with a fauna found in the Salt Range of Pakistan.