Topics: Pleistocene, Australia, Climate change Pages: 9 (3051 words) Published: August 12, 2011
Diprotodon, meaning "two forward teeth", sometimes known as the Giant Wombat or the Rhinoceros Wombat, was the largest known marsupial that ever lived and the last of the extinct, herbivorous Diprotodontids. Diprotodon was the first fossil mammal named from Australia and one of the most well-known of the mega fauna. It was widespread across Australia when the first indigenous people arrived, co-existing with them for thousands of years before becoming extinct about 25,000 years ago. Distribution and Abundance

Diprotodon is known from many sites across Australia, including the Darling Downs in southeastern Queensland: Wellington Caves, Tambar Springs and Cuddie Springs in New South Wales; Bacchus Marsh in Victoria; Lake Callabonna, Naracoorte Caves and Burra in South Australia. It is believed that Diprotodons could be found in all parts of Australia except in Tasmania. Until recently it was unknown how many species of Diprotodon had existed. Sir Richard Owen, a well- known palaeolontologist, studied them and gave the genus the name, Diprotodon in 1938. Wikipedia Reports 4 species : Diprotodon optatum, Diprotodon minor, Diprotodon laden, Diprotodon annextans.

Evolution of the Flora
The past 2 million years have been characterized by marked instability of the vegetation caused by dramatic cyclical fluctuations in climate. The remaining evergreen rainforest was further stressed. Evidence from southeastern Australia indicates that rainforest and Sclerophyll vegetation had very restricted distributions within a predominantly steppe vegetation during the cold dry periods of the ice ages.

These colder conditions would have also made it easier for cold-adapted herbaceous plants from overseas to colonize Australia. By around 750,000 years ago, the vegetation had become adapted to the climatic changes. This pattern was broken within the last glacial cycle, possibly 140,000 years ago, with substantial replacement of the remaining rainforest and fire-sensitive sclerophyll vegetation by fire-tolerant communities, especially those dominated by eucalypts.

This change was accompanied by significant increases in charcoal due to an increase in burning, perhaps the result of Aboriginal activities. Effects of this increase were probably greatest during the height of the last ice age, between about 20, 000 and 10,000 years ago. Today’s plant distributions have developed only within the past 10,000 years under higher temperatures and rainfall levels and have been affected by frequent fires.

The Historical Development of Fauna
The development of contemporary climatic patterns in Australia – of monsoonal rains across the north, Mediterranean winter rains across the south, year-rain only on the mountain ranges of the coast, and low erratic rain inland – has had the effect of zoning the flora and fauna. Fauna Today

Within the concentric faunal zones, the climatic fluctuations of the past several million years created cyclic make-and-break connections around the fringe of the continent. During cold, dry spells, the regional faunas were split and compressed into refugia and the fauna specied into isolation. When conditions ameliorated during the warmer, wetter periods between the ice ages, the isolated stocks expanded with their habitat and remet, to overlap or, if the speciation had not been completed to interbreed. In this way, rings of species formed around the periphery of the continent. Many of the refugia are self-evident from the number of endemic forms now present there.
Evolution of Climate
In “Pleistocene Climate Variation” compline by J.Richerson from the University of California, Richerson states that, using a variety of proxy measures of past temperature, rainfall, ice volume mostly from cores of ocean sediments, and ice caps, paleoclimatologists have constructed an increasingly detailed picture of the climate deterioration over the last few million years, culminating in the...
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