The Unique Australian Environment

1. The Unique Australian Environment

2. Gondwana • Gondwana was a southern precursor supercontinent. Its has been estimated to have begun its separation 570 to 510 million years ago. • All land masses, what we know call countries, were originally joined together when the Earth was created billions of years ago. The earth’s crust was still molding and transforming its shape and during this time Pangaea and consequently Gondwana was formed. • Gondwana was made up of many continents that are now found in the southern hemisphere. These included Antarctica, South America, Africa, Madagascar, Australia-New Guinea, New Zealand as well as Arabia and the Indian subcontinent.

3. Pangaea and Laurasia • Pangaea was originally the first land mass that is known to have occurred on Earth. • When Pangaea broke apart during the Jurassic period it formed two very large continents that we now know as Gondwana and Laurasia. These two continents were similar in size although Laurasia was situated in the northern hemisphere and Gondwana the southern hemisphere. • The continents that exist today have taken almost half a billion years to get this far. • Continental drift theory is the movement of the Earth’s crust or tectonic plates. These plates move at approximately less than two centimetres per year so for a whole continent to have moved thousands of kilometres would have taken an enormous amount of time. • This effect is still continuing today and is responsible for mountain ranges, such as the Himalayas, and earthquakes. It is predicted that Australia will eventually collide with southern Asia. Pangaea

4. Animals and Dinosaurs • Animals that may have originated in other continents yet are now found commonly in Australia are crocodiles and some birds. Fossil records have also shown that eucalypts, banksias and acacias may also have originated from the supercontinent. • Dinosaurs were still alive at the time of Gondwana and when the southern supercontinent was breaking apart. This occurred 100 million years ago and is known as “The Cretaceous” period. Dinosaurs that became stranded on the land mass that we now call Australia, included the Austrosaurusmckillopi and Leaellynasauraamicagraphica. • The climate was warm and moist at this time and as a result marsupials have been able to survive for millions of years from the supercontinent of Gondwana until now. • Yes. The break up of Pangaea would defiantly have affected the dinosaur population. Some species, especially herbivores, would have become extinct because the change in climate might have destroyed their food source. This would then lead to the extinction of other carnivore dinosaurs because their food source is no longer around either. • This change in climate would have also benefited other dinosaurs that had been able to adapt more rapidly then others and take advantage of new species of plants etc.

5. Adaptation to the harsh Australian Climate • Plants and animals would have had to change their diets, habitats and physical properties such as fur to survive the changing climate that was associated with the fragmentation of Gondwana. • Characteristics that enable a plant or animal to survive and adapt to changing conditions are located in their DNA. These genetic codes are the foundations that, for example, enable a plant to extend its roots further into the ground to access water or an animal to change its diet based on what is available within its environment. Plants also altered the shape and texture of their leaves to reduce moisture loss.

6. Humans • Humans managed to spread onto different continents by having a genetic ancestor on a continent as Gondwana beganbreaking apart. This is still a largely debated topic and is yet to be proven correct. It has also been said that human colonies developed individually in different parts of the world and then interbred to expand the population. This is known as the “regional continuity” theory. However roughly about 40,000 to 50,000 years ago aboriginals from Indonesia came across the ocean to the Australian mainland. They did • Humans have been said to develop from apes who have the most closely related genetic code to ourselves. This is known as the Darwin Theory of Evolution and it states that all life is related and has descended from a common ancestor.

7. Bibliography • http://en.wikipedia.org • http://www.kavenga.com • http://www.raceandhistory.com • http://www.onelife.com THE END