fauna and palaeoecology:
i) The fossil
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
The exquisite preservation of the Victoria Fossil Cave material enabled
Wells and Nichol (1977) to reconstruct the hand of the Marsupial Lion
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.
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.
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.
| 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,
S. andersoni, S. gilli,
and Procoptodon rapha; the Marsupial lion Thylacoleo carnifex;
the diprotodontoids Zygomaturus trilobus and Palorchestes azael;
the giant echidna
Zaglossus ramsayi; the giant Australian python
naracoortensis; and the giant Australian megapode
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.
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).
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).
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
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.
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.