Australia has split from Antarctica in responce to seafloor spreading. The early Tertiary saw the continent going through a wet phase, with large tropical forests.

As for life - well, some changes have occured. Not all of the dinosaurs are around: all groups except for the birds are extinct.

Way back during the Mesozoic, small-to-medium sized mammals had been roaming around. One branch of the mammal family tree - the "monotremes" - lays eggs from which their young hatch, just like the dinosaurs. Another branch of the mammal family tree nurtures it's young in a pouch. These are the "marsupials". And a third branch - one that isn't very important in Australian history until very recently (with the exception of rats and bats) - doesn't use a pouch, and has a placenta inside the womb to nurture their unborn children. These are the "placental mammals". In Australia, it is the marsupials that become the dominant large land animals of the Cainozoic (a.k.a. "Cenozoic") Era.

One of the largest and most successful groups of marsupials are the "diprotodontians". They included a huge range of forms, from long range roaming animals to small provincial things, from meat-eaters to plant-eaters to omnivores, from some of the largest mammals in Australia to some of the smallest.

• Palaeocene (Palaeogene) (65mya - 56.5mya)

The diprotodontians (these are a kind of marsupial; see above) are thought to have gone through much diversification in the early Tertiary Period, as during their first appearances in the fossil record, they are almost all already as diverse as today. It's unfortunate that we know so little of their original diversification.

• Eocene (Palaeogene) (56.5mya - 35.4mya)

In the early Eocene, global temepratures rose somewhat. They did again in the early-to-middle Eocene.

In the middle Eocene, rainforest conditions become restricted to the south-east. The earliest bat known to have lived in Australia existed at this time. Bats are placental mammals - unlike the monotremes and marsupials living in Australia up to this point. They are the odd ones out, and the latest group of land animals to gain the ability to fly.

A significant decline in global temperatures takes place at the end of the Eocene epoch.

Dinosaurs: Penguins are known to have lived in Australia from at least this point onwards.

• Oligocene (Palaeogene) (35.4mya - 23.3mya)

About 26mya, grasses first appear around the world.

The late Oligocene gives us a monotreme in the form of the platypus Obdurodon insignis, almost identical to the living Quarternary platypus (Ornithorhynchus insignis). The ancestors of the platypus go back into the Mesozoic Era.

The earliest "dasyurid" is known from this time. Dasyurids are marsupials that probably developed from the didelphids, who had originated in the Americas beforehand. Ankotarinja is an Australian didelphid/dasyurid from the late Oligocene to Middle Miocene.

Thylacinids (including species of Thylacinus, the "Tasmanian wolf" or "Tasmanian tiger") are known from this time, in Queensland.

Notoryctids ("marsupial moles") are known from a lush forested region at this time - modern notoryctids are confined to deserts.

Within the Diprotodontia, three seperate genera of koalas existed (as opposed to the single species around in the Qarternary - today) in the late Oligocene. Diprotodontoids (the diprotodontoids include 2 families: diprotodontids and palorchestids, and are contained within the group "Vombatimorphia") are also known from the late Oligocene.

The "thylacoleonids" are carnivorous diprotodontians: Priscileo is from the late Oligocene and belongs to this group. "Macropodids" (kangaroos) appear at this time.

• Miocene (Neogene) (23.3mya - 5.2mya)

Another increase in global temperatures occurs in the early to middle Miocene epoch. Then a significant drop in global temperature occured in the middle of the Miocene epoch.

During the early to middle Miocene, another monotreme is known: Zaglossus robusta, a large echidna.

Marsupials: At this time, the vombatiformes may have been going through a relative decline. This is when they first are known to us, however. Their sister group among the Diprotodontians (the order that the group 'vombatiformes' belongs to), the phalangeridians, began flourishing during the Neogene (Neogene = Miocene&Pliocene epochs together).

During the mid-Miocene, Propalorchestes, a small "maruspial tapir" was present. Sheep sized zygomaturines (diprotodontids) were around in rainforest habitats. Larger diprotodontids also existed. As did the rare, large, and possibly carnivorous 'propleopines', a sister group to modern rat-kangaroos. Twelve million years ago, wet tropics existed in the centre of the continent. After the mid-Miocene, the "megafauna" of large animals may have begun to appear possibly as a result of the shift from forests to more open grasslands, as Australia drifts north.

The late Miocene saw the thylacinids (Dasyuromorphs) represented by Thylacinus potens, the size of a modern fox. It also saw the thylacoleonids represented by the dog-sized cat-like Wakaleo vanderleueri and species of the small Priscileo. Another line of thylacoleonids existed then too (this other line would lead to the larger Thylacoleo itself later on). Diprotodontids represented by small species. The Ilariids were present, in the cow sized Ilaria.

In the Late Miocene, episodic droughts struck in the interior. This could possibly mark the time when Australia's drift brought it near to it's current location. Grazing animals are appearing (eg// forms of kangaroos).

• Pliocene (Neogene) (5.2mya - 1.64mya)

Large marsupials existed then. Such as zygomaturine Plaisiodon, and diprotodont Pyramios. The palorchestids had reached a great size with Palorchestes paini.

The first macropodids known appeared, in the form of Protemnodon and Sthenurus. Macropodids as a whole diversified greatly, leading to many various genera. They included both grazers and browsers. Such animals probably appeared as a result of the more open grassland habitats, which were more suited to grazing animals and animals that could move fast over long distance, as opposed to the forests of the pre-mid-Miocene. The related potoroids included carnivorous forms (been around since mid-Miocene), such as Propleopus and Ektadelta. The thylacoleonid Wakaleo alcootaensis, a bit larger than the Miocene species, lived.

Species of a large python (Wonambi), and the giant Megalania, a varanid lepidosaur. The archosaurs boasted large Crocodylus species. And Dromornis stirtoni, a huge dormornithid bird, existed along with it's relatives during this epoch.

Rodents appear on the Australian continent, aside from the already-present bats, these are the only placental mammals on the continent.

In the Late Pliocene, the large Zygomaturus and its relatives, other huge diprotodontids, roamed. Thylacoleo prissidens, a larger thylacoleonid ("marsupial lion") than its predecessors (eg// Wakaleo) lived. The palorchestids featured the big Palorcheste parvus.

The current period (Quarternary) of the current era (Cenozoic/Cainozoic).

• Pleistocene (1.64mya - 0.01mya)

During the Pleistocene, the huge varanid Megalania prisca lived. As did the horned tortoise Meiolania, and the crocodile Quinkana, and "marsupial lion" Thylacoleo carnifex, the same size as the Late Pliocene species T. prissidens. The dasyuromorph Sarcophilus laniaris, a Tasmanian devil larger than it's present day relatives, was also around.

Also present: the lineages of possibly carnivorous potoroids such as Ektadelta.

Among the mammalian herbivores, 1 - 2 ton Diprotodon opatum lived, and the 200 kg gaint wombat Phascolonus gigas, and the palorchestids ("marsupial tapirs") grew to large sizes in Palorchestes azeal, bigger than P. parvus of the Late Pliocene.

Giant kangaroos (the largest: three metre tall Procoptodon goliah) roamed, along with their smaller more familiar relatives. These macropodids included both the long-nosed grazing forms, and the short-faced browsing varieties.

Phascolarctus (koalas) were just a bit bigger than the present day animals. Their range extended a lot further, as well.

Monotremes: The long-beaked echidnas hung around - like 20kg Zaglossus hacketti, and the slightly smaller Zaglossus ramsayi.

The Pleistocene, in short, was very similar to the Pliocene. The Early Pleistocene probably included many of the same species present from the Pliocene, and certainly the same genera were mostly around all the way up to the Holocene.

• Holocene (0.01mya)

Earliest known "myrmecobiids" (numbats), a sister group to the dasyurids.

The related thylacinids are now represented only by a single species, Thylacinus cynocephalus, the "Tasmanian tiger".

About 40,000ya, humans were definately on the continent. By this time they had brought with them a breed of Canis: the dingoes. The introduction of these two major foreign predators no doubt had some impact on the ecosystem. This is the addition of at least two new placental mammal groups too - "primates" (represented by the humans) and "carnivores" (represented by the dingoes) - to the bats and rodents already present.

About 26,000ya, the last Australian dromornithid birds known.

18,000ya, last global glacial maximum. Glaciers in the highland areas around central Tasmania.

1788 sees the beginning of another wave of human invasion. European settlers arrive on boats, bringing many more foreign species along with them. Another sequence of accelerated extinctions has its beginnings here.

Immigration, mostly by Irish and English settlers, would follow.

The Gold Rushes of the middle of the 19th century - beginning 1851 - have large impacts on human society. Notably the immigration of many more settlers from Asia this time.

The year 1900 sees the official political independance of a new nation - "Australia" - whose territory includes the entire continent of Australia. Events in Europe - the First World War of 1914-18 - sees Australian involvement, altering the social climate around this period.

The extinction of the thylacines occurs during the 1930s when the last Tasmanian tiger seen alive dies in captivity.

The middle of the century - beginning 1941 - sees the nation of Japan making invasive moves around the Pacific. Japanese forces make an attack on a major coastal city (Sydney) and progress to New Guinea, north of Queensland and over the sea, where they are stopped.

Another wave of immigration from Europe begins soon after.

In the 1960s, aborigines are given the right to vote in elections.

Overall, the Holocene, beginning from hundred thousand years ago, is a predictable phase of extinction. Australia had been isolated from the rest of the world during it's drift north from Gondwana, causing ecosystems on the continent to evolve in their own way. When it came close to Asia, however, new species would be able to cross onto the continent, impacting the fauna already present. Added to that, technology allowed humans from Europe to follow after the humans who had crossed through Asia to land on the continent, and much the same thing happened. This should continue as Australia drifts into Asia in the coming millions of years and the Australian faunas are introduced to Asian faunas.

About 50 million years later, barring any catastrophic changes in the pattern of continental drift, it is predicted that Australia will join South-East Asia, which is moving south. Expect even more faunal mixing, along with extinction and new radiations and adaptations.