© The Authors, 2009. Journal compilation © Australian Museum, Sydney, 2009 
Records of the Australian Museum (2009) Vol. 61: 39-48. ISSN 0067-1975 
doi:10.3853/j.0067-1975.61.2009.1518 
New Records of Plio-Pleistocene Koalas from Australia: 
Palaeoecological and Taxonomic Implications 
Gilbert J. Price 1 *, Jian-xin Zhao 1 , Yue-xing Feng 1 and Scott A. Hocknull 2 
1 Radiogenic Isotope Facility, Centre for Microscopy and Microanalysis, 
The University of Queensland, St. Lucia 4072 Queensland, Australia 
g.pricel @uq.edu.au 
2 Geosciences, Queensland Museum, 
122 Gerler Road, Hendra 4011 Queensland, Australia 
Abstract. 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 significant 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 first 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 significant 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 significant 
Middle Pleistocene climate change. 
Price, Gilbert J., Jian-xin Zhao, Yue-xing Feng and Scott A. Hocknull, 2009. New records of Plio-Pleistocene 
koalas from Australia: palaeoecological and taxonomic implications. Records of the Australian Museum 61(1): 
39-48. 
Koalas (Phascolarctidae, Marsupialia) are Australian 
endemic, relatively large-sized (c. 10 kg), arboreal marsupials 
that occupy a similar ecological niche to placental lemuroids 
or sloths (Murray, 1984). The modern Koala, Phascolarctos 
cinereus, is the only surviving member of an ancient and 
diverse family of marsupials, with the oldest members 
known from the Late Oligocene (Black, 1999). Six to 
seven genera and 18 species (several undescribed) are 
currently recognized (Black, 1999). Phascolarctids are 
separated from all other vombatiformes (i.e., wombats, 
marsupial “lions”, illarids, wynyardiids, maradids, and 
diprotodontoids) on the basis of their selenodont dental 
morphology and occupy a position near the base of the 
diprotodontian ordinal tree (Archer, 1976; Archer & 
Hand, 1987). A recent molecular phylogeny supermatrix, 
temporally-constrained using dated occurrences of fossil 
taxa, suggested that koalas diverged from vombatoids 
during the Middle Eocene (Beck, 2008). 
* author for correspondence 
