The Fossil History of Australia

Cainozoic Era

Tertiary Period

(66.4 to 1.8 million years ago)

The Tertiary period is the first part of the Cainozoic era, and is generally divided into epochs called Paleocene, Eocene, Oligocene, Miocene and Pliocene, as each of these had unique fauna relating to that time.

The Australian landmass was now fully separated from Antartica and began its move northwards. The world temperature was not as warm as previous and the South Pole was beginning to cool, particularly after the Eocene epoch. The isolation of Australia meant that many types of flora and fauna developed unique forms not seen elsewhere.

Without the competition from dinosaurs and many reptiles, marsupials began to proliferate. Several different forms of possum are evident from fossil remains found from this time. From these, it is believed that the kangaroo may have evolved around the Miocene time. As the flora changed from rainforest to grasslands, the kangaroos flourished, with some species growing to over 3 metre tall.

Dating back to the Tertiary period, remains of placental mammals have been found as bats on the land, as a freshwater dolphin in the inland lakes, and as whales in the sea. Other fauna such as nautiloids, molluscs and crabs were found in the marine environment as well as lungfish and bony fish.

On land, reptiles still made a presence, including crocodiles similar to those in existence today. Lizards were not so common, although a large goanna was found to live on the eastern part of Australia. Remains of snakes and frogs form part of the history of the Tertiary period.

Penguins, pelicans and ducks were among the bird fossils from the Tertiary period, as well as a large bird which looked like an emu, although unrelated to the current emu population.

From the middle of the Tertiary period, there were many new species of flora including the eucalypt and the arcacia, which are so characteristic of Australia today, and which thrived in the changing climate.

Eucalypt

The later part of the Tertiary period was a much drier time for Australia, with a further reduction in rainforests, drying up of lakes, and formation of the inland deserts. The Pliocene also saw the appearance in Australia of another placental mammal, the rodent family.

 

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