Palaeoecological analyses of Riversleighʹs Oligo-Miocene sites: Implications for Oligo-Miocene climate change in Australia

During the Cenozoic, Australian environments changed from being dominated by warm and humid rainforests to mainly arid/semiarid habitats comparable to those found today. Northern Australiaʹs Oligo-Miocene palaeoenvironment were analysed using mammalian assemblages from the Riversleigh World Heritage Area, northwestern Queensland. Limitations of fossil assemblages were minimised using Minimum Sample Richness and taxonomic distinctness analyses because these identify under-sampled, unrepresentative and taxonomically-biased fossil assemblages which can then be removed from the overall analysis. Cenogram and body mass distribution methodologies were used to help determine the palaeohabitats of seventeen sites from Riversleigh that span the late Oligocene to early Miocene, middle Miocene and early late Miocene. The results suggest a change of environment through time, with the late Oligocene of Riversleigh represented by an open forest, the early and middle Miocene by rainforest, and the early late Miocene represented by open forest.