The distant ancestors of some of Australia's fauna lived when our land was part of the giant super continent. Much of it was covered by rainforests. About 60 million years ago, shifts in the Earth's surface began to separate Australia from Antarctica and it started to move slowly northwards, carrying animals that would survive after most of the relatives they left behind in other landmasses died out.

For many millions of years most of Australia remained covered by rainforests. Around 15 million years ago, the continent became drier and gradually most of the rainforests were replaced by eucalypts, acacias and other plants suited to dry conditions. Some mammals remained in the shrinking rainforest, while others, such as the Koala, adapted their lifestyles and diets so they could survive in the new habitats.

The Diprotodon, a giant herbivorous marsupial
Above image © Queensland Museum

As recently as 30,000 years ago, Australia was home to a group of very large animals, the MEGAFAUNA. These giant animals included: -

• A leaf-eating kangaroo, Procoprodon, which stood 3 metres high
• A flesh eating marsupial lion, Thylacoleo
• Giant wombat called Phascolonus
• The giant herbivorous, rhinoceros sized, wombat-like marsupial, Diprotodon, which may have survived until 6,000 years ago.

The eventual arrival of humans changed the existence of Australia's mammals in many ways. Humans introduced many placental mammals to Australia. The Dingo came with seafarers from Southeast Asia. The house mouse and 2 rat species stowed away on the First Fleet in 1788. Europeans deliberately introduced cats, dogs, rabbits, hares, foxes, horses, donkeys, pigs, camels, sheep, cattle, water buffalo and goats, as pets, food animals and working animals. Some domestic animals, like cats and dogs, have become feral and, like foxes, prey on native Australian animals and compete with them for food and shelter while others change their habitat.

There are 3 different sorts of mammals separated on the ways they produce their young.

• Monotremes - lay soft-shelled eggs.
  The tiny young that hatch from monotreme eggs are naked, blind and have undeveloped hind limbs. They use their forelimbs to drag themselves to their mothers' belly, where it suckles on a patch where milk oozes onto the skin.
• Platypus
• Echidna
  
  
• Marsupials - give birth to tiny young that are naked, blind and have undeveloped hind limbs.
  The baby uses its forelimbs to drag itself to one of its mother's nipples, where it will attach itself. Here, it suckles milk and completes its development. It may be protected by a pouch or by folds of skin.
• Dasyurids - eat animals of all types and sizes
• Bandicoots & Bilbies - eat invertebrate animals and fungi
• Marsupial Mole - eats burrowing insects
• Numbat - eats insects (termites)
• Wombat - eats shrubs and grass
• Koala - eats leaves
• Possums & relatives - eat leaves, nectar, fruit, sap and insects
• Kangaroos & relatives - eat shrubs and grass.
  
  
• Placental Mammals - keep their young ones inside their bodies until they are well developed.
  This is possible because a placenta links the blood vessels of mother and baby and prevents the mother's body from rejecting the baby. Once born, the baby suckles milk from its mother's nipples when hungry.
• Flying Foxes & Bats
• Rodents
• Seals
• Sea Lions
• Whales
• Dolphins
• Dugong
• Dingo

The world's birds have been placed in 29 orders. One order, the Passerines (perching or song birds) includes more species than all the 28 orders put together. Australia's 750+ species of birds belong to 20 of the 29 orders. About half of Australia's species are non passerines and half are passerines. The major grouping of Australian birds are shown below.

The five families of Australian Lizards are:

• Geckos
• Leggless Lizards
• Dragons
• Monitors
• Skinks

Scientists place the world's spiders, scorpions, ticks and mites, and their allies, in a Class Arachnida. Spiders are placed in the order Araneae. There are 116 families of spiders in the world, 69 are found in Australia. The Australian spiders are placed in two groups. The "Primitive" group contains 10 families, while the "Modern" group contains 59.
Australia's spiders are grouped as shown below:

Some links about Australian Fauna

A personal homepage with information on Australia's fauna
DoAustralia.com - Information and images of Australia's fauna
Sassy's Home Page - Unique Australian Animals
All Australian - information on australian fauna