New Records of Plio-Pleistocene Koalas from Australia: Palaeoecological and Taxonomic Implications
Gilbert J. Price1*, Jian-Xin Zhao1, Yue-Xing Feng1 and Scott A. Hocknull2
2 Geosciences, Queensland Museum, 122 Gerler Road, Hendra 4011 Queensland, Australia
Koalas (Phascolarctidae, Marsupialia) are generally rare components of the Australian fossil record. However, new specimens of fossil koalas were recovered during recent systematic excavations from several eastern Plio-Pleistocene deposits of Queensland, eastern Australia, including the regions of Chinchilla, Marmor and Mt. Etna. The new records are signifcant in that they extend the temporal and geographic range of Plio-Pleistocene koalas from southern and southeastern Australia, to northeastern central Queensland. We provide the frst unambiguous evidence of koalas in the Pliocene Chinchilla Local Fauna (phascolarctid indet. and Ph. ?stirtoni): important additions to an increasingly diverse arboreal mammalian assemblage that also includes tree kangaroos. The persistence of koalas and local extinction of tree kangaroos in the Chinchilla region today suggests that signifcant habitat and faunal reorganization occurred between the Pliocene and Recent, presumably reﬂecting the expansion of open woodlands and grasslands. Other koala records from the newly U/Th-dated Middle Pleistocene Marmor and Mt. Etna fossil deposits (Phascolarctos sp. and Ph. ?stirtoni), along with independent palaeohabitat proxies, indicate the former presence of heterogeneous habitats comprised of rainforests, open woodlands and grasslands. The lack of such habitat mosaics in those regions today is likely the product of signifcant Middle Pleistocene climate change.