Discovery of Iapetognathus fauna from far western New South Wales: towards a more precisely defined Cambrian–Ordovician boundary in Australia.

Conodont speciesIapetognathus fluctivagusandIapetonudus ibexensisare documented for the first time from Australia. The former is the primary marker internationally defining the base of the Ordovician, and the latter is also a distinctive species previously recorded only from the base of the Ordovician in North America. Both species were recovered from a single sample in the Kandie Tank Limestone of the Kayrunnera Group, located about 50 km west of White Cliffs in far western New South Wales. Other species recovered from this sample includeProoneotodusspp.,Cordylodus lindstromi,Cordylodus proavus,Hirsutodontus simplex,Teridontus nakamuraiandVariabiloconussp. Recognition of theIapetognathus fluctivagusBiozone in the Kandie Tank Limestone supports its correlation with the Green Point section (Global Stratigraphic Section and Point for the base of the Ordovician) in western Newfoundland and the Lawson Cove section of Utah (Auxiliary Stratigraphic Section and Point), as well as sections in Asia and South America. Review of other sections in Australia and elsewhere spanning the Cambrian–Ordovician boundary confirms that, in the absence ofI. fluctivagus, the presence ofC. lindstromiis a good proxy for this level. [ABSTRACT FROM AUTHOR]