8.5 EVOLUTION OF AUSTRALIAN BIOTA
8.5.1 Evidence for crustal plate rearrangement and continental drift
220.127.116.11 Identify and describe evidence that supports the assertion that Australia was once part of a landmass called Gondwana, including:
matching continental margins
position of mid-ocean ridges
spreading zones between continental plates
fossils in common on Gondwanan continents, including Glossopteris and Gangamopteris flora, and marsupials
similarities between present-day organisms on Gondwanan continents
Matching continental margins
Evidence of continental drift comes from the ways the continents fit together and continuity of rocks between their opposite edges.
Position of mid-ocean ridges
The mid-ocean ridges form the boundaries of the Earth's crustal plates where the plates move apart, the crusts move because of lava added to the ridges, which causes earthquakes and volcanoes at these regions.
Spreading zones between continental plates
Sea floor spreading occurs where two crustal plates move apart, hot molten material rises and cools and becomes rigid. This then forms part of the plates on either side of the spreading zone.
Fossils in common on Gondwanan continents, including Glossopteris and Gangamopteris flora and marsupials
Glossopteris and Gangamopteris are two plants which are distinct in all the continents of Gondwana found from the Permian Age.
Mammals, especially marsupials provide evidence for plate tectonics and the past existence of Gondwana. When Australia became isolated from the rest of the world, the marsupials' evolved and diverse species flourished. The dasyurids (Native cats and marsupial mice) have several features in common with South American marsupials.
Similarities between present - day organisms on Gondwana continents
Flora of southern continents - South America, South Africa, Australia and New Zealand has many features in common.
The family Myrtaceae includes the plant genera Eucalyptus, Callistemon, Melaleuca and Leptospermum. Found in Australia, South America and Southern Asia.
The family Proteaceae includes the plant genera Banksia, Grevillea and Telopea. Found in New Zealand, South America, South Africa and Australia.
Flightless birds have also been examined, these include the Rhea (S. America), Emu and Cassowary (Australia), Ostrich (Africa) and Kiwi (New Zealand). The distribution of these flightless birds on these different continents is due to the super continent, Gondwana.
8.5.2 The changes in Australian flora and fauna over millions of years have happened through evolution
18.104.22.168 Discuss examples of variation between members of a species
All species of animals have variations in characteristics to help them adapt to their environment, and should be able to be inherited controlled by genes.
These variations come from
Recombination of genes