Price et al.: koala palaeoecology 
41 
Fig. 1. Oligocene-Pleistocene fossil localities where koalas have 
been recovered, including present study sites (Chinchilla, Marmor 
and Mt. Etna). Shaded area indicates historic (i.e., post-European 
settlement in Australia) geographic range of the modern Koala, 
Phascolarctos cinereus. 
Bluff Downs Local Fauna, and Hamilton Local Fauna), 
suggests a Middle Pliocene age (Whitelaw, 1991; Tedford 
et al., 1992; Mackness et al., 2000). 
Marmor. Site QML1420 is located in Marmor, central 
eastern Queensland (Fig. 1). QML1420 is a brecciated 
limestone cave deposit, with sediments dominated by grey 
to brown clays and limestone clasts (Hocknull, 2005). The 
deposit contains typical Pleistocene megafauna including 
Diprotodon optatum, Thylacoleo carnifex and Macropus 
giganteus titan (Longman, 1925) ( D. optatum and M. g. 
titan taxonomy up-dated following Price (2008b) and 
Dawson & Flannery (1985), respectively). Direct U/Th 
dating based on teeth from such taxa returned minimum ages 
of 122-154 ka (Table 1) suggesting that the assemblage is 
Middle Pleistocene or older. The assemblage lacks faunal 
elements typical of Pliocene assemblages and on the basis of 
biocorrelation to nearby well-dated deposits of the Mt. Etna 
region (Hocknull et al., 2007), site QML1420 is unlikely to 
be older than Middle Pleistocene. 
Mount Etna. Site QML1384 (Unit “L.U.”; Elephant Hole 
Cave) is located at Mt. Etna, central eastern Queensland 
(Fig. 1). It is a brecciated limestone cave deposit, with 
sediments dominated by red/yellow/grey clays with 
occasional gravel and cobbles (Hocknull, 2005). Direct U/ 
Th dating based on a macropod bone provided an age of 
267±5.2 ka (Table 1). However, due to unknown rates of U 
uptake, the date should be regarded as a minimum age only. 
This interpretation is supported by U/Th dating of calcite 
recovered from the hollow of long bone, which returned 
an age of 331.6±14 ka (Table 1). This age is likely to be 
closer to, but still younger than, the true age of the fossil 
assemblage. A maximum age has not been determined for 
QML1384 “L.U.”, but based on faunal similarities to other 
dated sequences in the region, the deposit is unlikely to be 
older than 500 ka (Hocknull et al., 2007). 
Systematic Palaeontology 
Super cohort Marsupialia Cuvier, 1817 
Order Diprotodontia Owen, 1866 
Suborder Vombatiformes Woodburne, 1984 
Infraorder Phascolarctomorphia Aplin & Archer, 1987 
Family Phascolarctidae Owen, 1839 
Phascolarctidae gen. et sp. indet. 
Figs 2, 3A 
Referred material. QMF52287, left dentary fragment, 
QML7, Chinchilla, southeast Queensland, Australia 
(Pliocene). 
Description. Dentary fragment with horizontal ramus broken 
anterior to P 3 alveolus and posterior to M 3 alveolus; surface 
bone slightly root-etched; cheek teeth crowns missing, roots 
present, alveolar border broken buccally; ventral border 
slightly in-turned lingually; mental foramen anteroventral 
to P 3 anterior alveolus; posterior mental foramen well 
developed, ventral to position between posterior root of M t 
and anterior root of M 2 ; symphysis strongly fused, very deep, 
extended posteriorly to below posterior root of M l5 kinked 
such that posteroventral border extends below ventral border 
of horizontal ramus, inclined posteriorly at posteroventral 
margin, inclined anteriorly at a low angle (35°); genial pit, 
c. 3 mm largest diameter, present at posterior ventral portion 
of symphysis, similar symmetrical but broken pit present on 
opposing dentary. 
Remarks. The dentary fragment is considered to be adult 
based on the presence of well-developed P 3 and M 3 alveoli, 
and a strongly fused symphysis. The dentary resembles 
phascolarctids in general morphology. However, QMF52287 
does not appear to be referable to any phascolarctid where 
the dentary is known. It differs from Nimiokoala, Perikoala, 
Madakoala, and Phascolarctos cinereus by: (a) being 
significantly more robust in terms of depth and width (Fig. 
3A); ( b ) possessing a more anteriorly positioned posterior 
mental foramen; (c) having a straighter ventral border; 
and (d) by possessing a relatively deeper symphysis that 
has a lower anterior ascending angle. QMF52287 is more 
gracile in comparison to Cundokoala yorkensis (a genus 
that is questionably distinct from Phascolarctos', see Black, 
1999) (Fig. 3A), but like Ph. cinereus, also differs from 
the former taxon in having a more anteriorly positioned 
posterior mental foramen, straighter ventral border, and 
deeper symphysis. The dentary of Litokoala is unknown, but 
on the basis of alveoli dimensions, is probably significantly 
smaller than QMF52287. QMF52287 differs from Perikoala 
and Madakoala in that the symphysis is more strongly 
fused, and the diastema is relatively longer. Well-developed 
symmetrical genial pits are present at the posteroventral 
base of the symphysis of QMF52287, but are not expressed 
as strongly in other koala genera. Well-developed genial 
pits occur in wombats such as Vombatus, but such pits are 
relatively larger, positioned relatively higher from the ventral 
border, and the pits commonly converge on each other on 
the left and right side of the symphyseal fusion forming a 
