Biology- Naracoorte Kanawinka Fault and the Naracoorte Flooding The first record of fossil bones from Naracoorte Caves came from a minister, Rev. Tension Woods, in 1859. He believed that these fossil bones were evidence of the Biblical Flood (described in the Bible, Genesis 6-8). There was no biblical flood, but the fossils had certainly suggested that Naracoorte had once been covered by the sea. Scientists exploring and studying the deposits at Naracoorte have tried to put together a puzzle of mammoth proportions.
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They constructed parts of the puzzle by finding tiny bones and fossilised teeth, the pollen of plants and certain geographic features. A meaningful picture had begun to emerge. The terrain features a limestone plateau along the Kanawinka fault. The limestone itself was deposited up to and included the Miocene epoch when the region featured a warm shallow ocean. Naracoorte limestone is richly endoved with the fossils of brachiopods, molluscs, sponges, corals and echinoderms. Fossilised remains of much larger marine species such as whales and sharks have also been reported.
About 800 000 years ago the Kanawinka fault moved, uplifting the Naracoorte limestone, raising the caves above the water table. Much of the limestone became covered and protected by sand dunes formed by the deposition of sand from the nearby sea. As water percolated downwards, dissolving some of the sand and limestone, ‘pitfall traps’ were formed. It is theorised that these pitfall traps claimed many animals for the caves below, accounting for much of the bone deposits. The flow of water into and through the caves would also have been responsible for the deposition of dead remains.
If the Kanawinka fault hadn’t moved, pitfall traps wouldn’t be formed resulting in an empty site with no real historic evidence of Megafauna or the life that was before us. We wouldn’t have discovered what we have today. Vegetation The animal fossils found at the Naracoorte site help construct a picture of the kinds of fauna that existed at different times. Pollen analysis had indicated the kinds of flora that existed. Core analysis of pollen samples in the Naracoorte area indicate that Eucalypts forest or woodland featuring an understorey of shrubs was followed by a period of open woodland.
This pattern occurred twice in alternating succession between 50 000 and 11 000 years ago. The area then became a Casuarina community that has persisted to the present day. Mega Fauna Fossils Some of the species of Mega Fauna that have been fossilised at Naracoorte include the giant Tasmanian devil, Marsupial lion, giant echidna, diprotodontoids and many giant kangaroos. Two more detailed examples include: Diprotodon- The Diprotodon is about 3m long and 2m high at the shoulder and looks like a giant wombat. They have five toes on their back feet that have short thick bones.
They also have two pouch bones. The flat area of vertebra where they join together shows that it is a mammal. Comparison with the modern wombat shows features that were needed to survive in the changed environment. Procoptodon- the Procoptodon is a giant short faced kangaroo with extremely elongated hind limbs and forward facing eyes. Their foot possesses a single large toe, ending in a hoof like nail. Comparison with modern macropods shows that the nearest living relative is the bonded wallaby. Modern-day Fauna Fossils
Some examples of modern-day fauna that are represented at the Naracoorte caves include frogs, lizards, turtle, snakes, birds, mice, possums, wallabies, the eastern grey kangaroo (macropus giganteus) the swamp wallaby (wallabia bicolor) the Tasmanian devil and the now extinct thylacine or Tasmanian tiger. Modern-day Species and the Environment Some researchers wrote that these extinctions occurred within 10 thousand years after the arrival of Australia’s indigenous people, and propose that these extinctions were a result of their over hunting and their practice of burning the changed vegetation.
Other researchers argue that these extinctions were caused by climate change that led first to the loss of the herbivore species then to the carnivores that preyed on them. It is suggested that the modern-day species that have been fossilized for tens of thousands of years did not have remarkable traits to continue existing. Over hunting and human interference also seemed to have a significant impact on their existence.