Kiana Cliff: a new fossil vertebrate site of probable last interglacial age from Eyre Peninsula, South Australia

The distributions of modern vertebrate species and their molecular phylogenetic relationships across southern mainland Australia point to a long and complex history of dispersal and vicariance shaped by climatic fluctuations and resultant vegetation shifts. Yet, there are relatively few Pleistocene vertebrate assemblages from the southern periphery that provide direct insight into which species lived where and when. Here we report on a new site, a cave-fill exposed high on Kiana Cliff on southwestern Eyre Peninsula, South Australia. The assemblage contains the remains of 17 mammal taxa, including six extinct kangaroos. Single grain thermally transferred optically stimulated luminescence (TT-OSL) dating reveals an age of 126 ± 10 thousand years for the fossil-bearing sedimentary infill, marking the assemblage as likely to be of last interglacial age. The presence on Eyre Peninsula of some species known from both the south-east and south-west of the continent suggests the potential for interchange and dispersal across the southern margin of the continent during the last interglacial period, or during glacial periods on the then exposed continental shelf areas. For species unable to penetrate the arid interior of southern Australia, Eyre Peninsula may have played a significant role in their local persistence during interglacial periods, and their east – west dispersal during lower sea-level stages of past glacials.