Fossil fauna and palaeoecology:

i) The fossil fauna:

    The Victoria Fossil Cave fauna has been studied by, among others, Smith (1971,1972,1975,1976,1985), Van Tets and Smith (1974), Van Tets (1974, 1985), Tyler (1977), Wells (1975, 1978), Wells and Nichol (1977), Wells and Murray (1979), Wells, Horton and Rogers (1982) and Wells, Moriarty and Williams (1984).  The remains of at least 93 vertebrate species have been identified, ranging in size from very tiny frogs to steer-sized marsupials.  It is essentially a terrestrial fauna with one aquatic element, the freshwater turtle cf. Emydura macquarii.  The Victoria Fossil Cave fauna typifies Australian Late Pleistocene terrestrial faunas in being comprised of a mixture of three categories of animals: 1, extinct species; 2, species that are extinct in the area but surviving elsewhere in Australia; and 3, species still living in the area.  The majority of the larger animals represent extinct species while the majority of the smaller mammals and birds represent modern species (although not all are living in the area today) (Smith 1976).

    Tyler (1977) has recognised 5 species of frogs, two of which still live in the caves today.  One of the Victoria Cave species, Geocrinia laevis, however, is not known from the Naracoorte area.  This retraction in range may be either the result of the increase in aridity of the southern Australian environment which occurred during the Late Pleistocene, or the desiccation of the environment due to water drainage and clearing of vegetation which occurred in the area following European settlement.

    Smith (1976) has identified 12 species of reptiles in the Victoria Cave deposits.  Nine of these still occur in the Naracoorte area today.  One snake, the Giant Australian Python Wonambi naracoortensis, represents a very large python with strong affinities to the extinct snakes of South America.  It is therefore part of the growing evidence for the southern continental affinities of much of Australia's vertebrate fauna.  The presence of such a large python in the southern part of Australia has been used as evidence of formerly more equable climates in this part of the continent during the Late Pleistocene.  Considering the Victoria Fossil Cave reptile fauna as a whole, it is interesting that there appears to be very little change in its composition throughout the known history of deposition.  Overall, it is an important assemblage within Australia because it represents an overlap zone between Bassian (cool temperate zone) and non-Bassian faunas.  Some of the Victoria Cave reptiles are not known today from the southern portions of the continent.  This overlap also suggests that there may have been less latitudinal climatic zonation during the Late Pleistocene than there is at present.

    Van Tets and Smith (1974) have studied the exceptionally well-preserved bird material from Victoria Fossil Cave.  They concluded that the bird bones may either have been washed into the caves or taken in by predators.  At present, there are too few bones to determine the most likely method of introduction.  Except for the giant Australian megapode (Progura naracoortensis), all of the bird species are known to have occurred in south-eastern South Australia in historic times.  All of the still-living species thrive today in wet coastal conditions although some also occur in the dry inland areas of the continent. Progura naracoortensis lived in open scrub (Van Tets, 1974) and was similar to the modern Malleefowl.  Its extinction may have resulted from the same processes that eliminated many of the larger mammals - possibly increased aridity and/or anthropogenic changes in the vegetation.  It is also possible that the introduction of the dingo by Aborigines adversely affected this large bird.

    Most studies of Victoria Fossil Cave vertebrates have concentrated on its mammals, for a number of reasons.  First, they are conspicuous parts of the fauna and hence have been collected in considerable abundance.  Second, the Victoria Cave mammals are represented by extaordinarily well-preserved materials which makes them particularly important in all kinds of analyses.  Third, because Pleistocene mammals have long been known from deposits throughout Australia, their biostratigraphic and palaeoecological significance in the Victoria Cave deposits is relatively easy to determine compared, for example, with the comparable record of fossil reptiles and frogs.

    Smith (1971, 1972) has presented analyses of the smaller mammals including the potoroids (rat kangaroos), petaurids (gliding and related possums), burramyids (pigmy possums), peramelids (bandicoots), thylacinids (Tasmanian tigers) and dasyurids (carnivorous marsupials).  Analyses of the age distribution of individual small mammals suggests that many if not most were brought into the cave by predators.  Among studies of middle-sized mammals, Flannery and Pledge (1987) used the important Victoria Fossil Cave wombat material in their analysis of the plesiomorphic wombat Warendja wakefieldi.  Pledge (1980) has reported on fossil echidnas including long-beaked echidnas (species of Zaglossus) which today survive only in New Guinea. Griffiths, Wells and Barrie (1991) have described a new genus of long-beaked echidna (Megalibgwilia ramsayi) from Victoria Fossil Cave. Archer and Dawson (1982) and Murray, Wells and Plane (1987) considered aspects of the diverse assemblages of thylacoleonids (marsupial lions) from the Victoria Fossil Cave deposits which enabled a revision of thylacoleonid diversity and phylogenetic systematics. Dawson (1982) also studied the fossil Tasmanian devils (Sarcophilus spp.) of eastern Australia, comparing them with the large collections from the Victoria Fossil Cave.

    The exquisite preservation of the Victoria Fossil Cave material enabled Wells and Nichol (1977) to reconstruct the hand of the Marsupial Lion Thylacoleo carnifex, and to interpret how it worked as a prey-capture mechanism.  They were also able to reconstruct, for the first time, the tarsal bones and most of the remainder of the hind foot of this leopard-sized carnivorous mammal.  They concluded that its limb proportions suggest that it may have been partly arboreal, although it probably did not pursue arboreal prey.  Its hand and foot were evidently suitable for grasping branches.

skeleton of Thylacoleo carnifex
A cast reconstruction of the skeleton of Thylacoleo carnifex.  This model is on display in Victoria Fossil Cave.

    Using the similarly well-preserved skulls and teeth of the Victoria Fossil Cave marsupial lions, Wells, Horton and Rogers (1982) studied jaw mechanics and the mechanisms involved in tooth sharpening.  They determined that the lower incisors were used for stabbing and the premolars for slicing flesh and bone.

    They proposed a leopard-like ecological niche, with marsupial lions hauling large kangaroos such as sthenurines into trees where they could be eaten at leisure, out of the reach of scavengers and other comparable-sized carnivores like the large Pleistocene Tasmanian tigers (Thylacinus sp.).

    The Victoria Fossil Cave is perhaps most famous for its extraordinarily rich record of kangaroos.  This assemblage is in broad terms typical for the Late Pleistocene of Australia except for two aspects: the preservation of the skull and postcranial material represented is unique; and the diversity of kangaroos in the fauna is strikingly high.  Overall, there are four groups of kangaroos represented: 1, species which are still living (e.g. the Red-necked wallaby (Macropus rufogriseus); 2, species which are still living but which no longer occur in the Naracoorte area (e.g. the Tammar wallaby, M. eugenii); 3, extinct species in extant genera (e.g. the Toolache wallaby, Macropus greyi); and 4, extinct genera (e.g. Procoptodon and Sthenurus).

    Among the more spectacular kangaroos in the Victoria Fossil Cave deposit were the species of Procoptodon, which were giant, short-faced browsers, and the species of Sthenurus, most of which were browsers (Wells and Murray, 1979).  The species of both of these genera are distinguished by placement in the subfamily Sthenurinae, a group that underwent an adaptive "explosion" sometime between the Middle Pliocene and the Middle Pleistocene, and a comparably "explosive" decline at the end of the Pleistocene.

skeleton of Simosthenurus occidentalis
Simosthenurus occidentalis, a large extinct species of leaf-eating kangaroo whose remains are prevalent in Victoria Fossil Cave.  The skull of an Eastern grey kangaroo (Macropus giganteus) is shown beside it for scale.

    The Banded Hare-wallaby (Lagostrophus fasciatus) is thought to be the sole surviving sthenurine, while the Swamp Wallaby (Wallabia bicolor) is one of few browsers left in Australia (although it also eats grass) and is possibly a living relative of the extinct Protemnodont kangaroos.  Among other Victoria Fossil Cave species, the Eastern grey kangaroo (Macropus giganteus) is a giant that managed to survive the Late Pleistocene extinctions (Flannery, 1981) although the living form is approximately 30% smaller than its Pleistocene counterpart.  In most of the more recent studies of Pleistocene faunas, environments and palaeoecology, the Victoria Fossil Cave material has played an important part in the development of new ideas (e.g. Wells and Pledge 1983; Wells 1975, 1978; Wells et al. 1984).

    One of the more controversial areas of research is the study of the Victoria Fossil Cave material to see what light it can shed about the temporal changes in size of Pleistocene vertebrates, there being a clear trend throughout the late Tertiary towards increasing size in the larger terrestrial mammals (e.g. the diprotodontoids and macropodoids).

    Among the giants represented in the Victoria Fossil Cave fauna are many elements collectively called the megafauna.  These include: the giant Tasmanian devil Sarcophilus cf. laniarius (= harrisii); the kangaroos Macropus titan, Macropus greyi, Sthenurus atlas, S. andersoni, S. gilli, S. maddocki, S. occidentalis, S. brownei, S. pales and Procoptodon rapha; the Marsupial lion Thylacoleo carnifex; the diprotodontoids Zygomaturus trilobus and Palorchestes azael; the giant echidna Zaglossus ramsayi; the giant Australian python Wonambi naracoortensis; and the giant Australian megapode Progura naracoortensis.

maxilla of Zygomaturus trilobus
Maxilla of Zygomaturus trilobus, a medium-sized species of diprotodontid marsupial whose remains are often found in Victoria Fossil Cave.  This particular example is exceptional in that all of the teeth are present and virtually intact.  Actual length - 200 mm.

    Eco-physiological theories for the rise and fall of the megafauna are hotly debated.  It has been suggested that the increase in size in these animals was a response to environmental change; a response to a decline in temperatures and the selective advantages large body size conveyed for retention of body heat.  Alternatively, decline in the nutritional value of plant food may have selected for larger body size (the herbivore that could eat more poor quality food had a better chance of retrieving what it needed).  Reasons for what appears to have been a comparable but more sudden Late Pleistocene decline in average body size among these same herbivorous lineages ("post-Pleistocene dwarfing") are no less controversial.  Main (1978) suggests that it may have reflected the selective pressure to reduce the time taken to produce young (smaller mammals in general having shorter gestation and weaning periods) in ecosystems where "good" seasons were becoming relatively unpredictible.

    As these areas of vigorous debate continue to develop, the Victoria Fossil Cave faunas will become progressively more important, in part because they may well provide evidence for contemporaneity of distinct species that elsewhere, on the basis of studies of more poorly-preserved faunas, appear to be successional populations of single species.

ii) Palaeoecology:

    When knowledge of the preferred habitats of the extant species present in the Victoria Fossil Cave fauna is combined with independent determination of the apparently preferred habitats of the extinct Victoria Fossil Cave species, it appears that the surrounding region supported dry sclerophyl forest to savannah woodland with substantial areas of heath, wet and dry grasslands and shrublands (Smith, 1971; Van Tets & Smith 1974; Wells et al., 1984).  This kind of environment was typical of south-eastern South Australia at the time of European settlement, and evidently for at least some periods of the Late Pleistocene.

    However, signficant fluctuations in Quaternary climates in other areas of Australia (Martin, 1984) suggest that the Naracoorte area too may have undergone perturbations in climate although the Victoria Fossil Cave fauna and that of the present day do not in themselves demonstrate climatic change.  Recent dating and palaeo-climatic research in collaboration with Ayliffe and Marianelli at ANU using speleothems provides a high resolution record of the climate spanning the last four glacial/interglacial cycles.

    Pollen data from Wyrie Swamp (80 km south of Victoria Fossil Cave) provide a good record of climatic change for the area (Dodson, 1977) and indicate that during the period represented by at least the younger sediments (as indicated by charcoal dates) in Victoria Fossil Cave, inland lakes passed from a period of high water level to an emphemeral condition and finally dried up, while coastal vegetation passed from eucalypt forest with scrub understory to an open woodland (Wells et al., 1984).  In the South-East, two periods of Eucalyptus forest or woodland with a shrub understorey alternated with two periods of open woodland, from 50,000 years ago to 11,000 years ago, followed by a Casuarina community that has existed to the present day (Dodson 1977, Martin 1984).

    The sediments in Victoria Fossil Cave accumulated over a longer period but reflect similar climatic fluctuations not inconsistent with pollen data.  The decline of the scrub understory with increasing aridity of the environment, is more likely to be reflected in analysis of the small mammal fauna from the deposits, material which has yet to be fully analysed (A. Baynes and R. Wells, in prep.).  Many species now extinct in this region such as Perameles gunnii, Zaglossus ramsayi, Thylacinus cynocephalus, Dasyurus maculatus and others may owe their decline to these fluctuations in climate.

    The period represented by the accumulation of sediments in Victoria Fossil Cave was an important time in Australia's ecological history as it was worldwide.  The Australian Tertiary and Quaternary climatic record is one of overall increasing aridity, marked by the development of very different climatic subregions within Australia and the eventual spread of central Australian deserts (Archer, 1984).   Widespread dune construction occurred in the interior coinciding with very dry periods which first began some time prior to 300,000 years ago (Bowler, 1976).  Although this dryness was in fact a marked feature of the Australian continent since the mid-Miocene, there were complex perturbations in this trend during the Pleistocene (Martin, 1984).  During the late Cainozoic, dry conditions coincided with relatively low

mandible of Sarcophilus harrisii (Tasmanian devil)
A partial fossil mandible of Sarcophilus harrisii (Tasmanian devil).  This species is represented in the deposits of Victoria Fossil Cave.  However, this particular specimen is from the Wellington Caves of New South Wales.  Actual length - 60 mm.
temperatures and wet with higher temperatures.  For Australia, the concept of glacial pluvials has been abandoned (Galloway and Kemp, 1981) and it is now understood that periods of glacial advance on other continents were times of extreme aridity in Australia.  In the northern continents, glacial advances are characterised by cold climate sediments (e.g. moraines, loess, solifuction deposits and gravel terraces).  In Australia, glacial phenomena were restricted to the Great Divide and Tasmania.  Evidence for climatic fluctuations has, as a consequence, come more from studies of the advance and retreat of low latitude deserts (Wells, 1978).

    Because the chronology of Quaternary climatic events and the relative ages of known Quaternary faunas in Australia are as yet poorly understood (Wells, 1978), opportunities to establish detailed stratigraphic and chronological data for rich faunas such as that from Victoria Fossil Cave are of considerable importance for the whole continent.

    The Late Pleistocene events that affected Australia's diverse habitats, including those that were anthropogenic, profoundly altered this continent's biotas.  After having evolved in complete isolation from the nearest terrestrial ecosystems for 30 million years (following this continent's separation from Antarctica about 45 million years ago), every change, no matter how slight, was far more signficant in terms of preservation of the world's natural heritage than were comparable changes elsewhere on other continents.  Only Australia maintains ecosystems dominated by marsupials; only Australia has monotremes.  As Rich (1982) points out, only Australia may have had over 50% of its native mammals (the marsupials) descended from a single family (the Microbiotheriidae which today survive only in South America).  In stark contrast, biotic interchange occurred regularly between South America, North America, Europe, Asia and Africa.

Acknowledgement: This subsection of Thylacoleo Revealed is based upon the following: HAND, S. 1988. Draft Nomination of the Pleistocene Fossil Vertebrate Deposits of Victoria Fossil Cave Naracoorte, South Australia for inclusion on the World Heritage List. Unpub. report to SA National Parks and Wildlife Service.
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