In the late Cambrian, Australia is largely underwater. It is a part of the continent Gondwana (and is directly connected to Antarctica along the current South Coast, and India and Tibet along the current South West Coast). The current East Coast faced northwards, and Western Australia faced southwards. The area that is currently Australia porbably lay between 5 and 40 degrees North of the equator, and made up the northwestern edge of Gondwana.

West Australia probably experienced a tropical climate, with high rainfall and temperature, though it wouldn't have been the kind of tropics we're familiar with: there were no plants then. The South was probably mainly desert.

Slight sea level rises occured during the middle Cambrian.

Meanwhile, a major event in the world's prehistory was occuring. The best record we have of this event comes from Canada, then underwater, on the continental shelf near Laurentia - on the opposite side of the world from the Australian region, and to the east across the sea from the eastern coast of Gondwana.

This event has been dubbed the "Cambrian Explosion". It was the geologically sudden appearance of a wide range of designs of animal. A few key designs survived to this day, and gave rise to all the plans of animal design we see around us.

(Prior to this event, though, Australia hosted some of the earliest known multicellular life. They were strange soft-bodied animals, including jellyfish-like creatures and stalked leaf-shaped things that don't exist anymore.)

During the middle of the Ordivician period, Australia - along with the movement of Gondwana - was crossing the equator, moving into the southern hemisphere.

Much of Australia was covered in deep water, or in other places warm shallow seas, once again. Land areas were subject to a warm, equatorial climate.

415mya, Australia's orientation has changed. The underwater East Coast (which faced north) now faces north-east, the North (which faced west) faces north-west, the South Coast - connected to the landmass of Antarctica - is oriented in a south-easterly direction.

Gondwana has moved south - as far south as one can go. The main mass of the continent (containing present-day Africa and South America) lies near the south pole. Australia and Antarctica make up an arm of the continent that lies north - reaching almost to the equator with Australia.

Its likely the West and the Centre of Australia were warm and arid. Warm, rainy climates are probable in the equatorial areas such as the north-east.

The land areas would have shown evidence of the first life on land - plants. Along with them, some early insects and other "arthropods" (many-legged creatures with hard, jointed exoskeletons) moved onto the land. Compared to today, the land of the Silurian would have seemed quite empty.

In the oceans though, life continued to flourish. Soft fishes (with no jaws or teeth) called "agnathans" swam through the seas that covered the East Coast of Australia. Ocean-dwelling scorpion-like creatures called "eurypterids" crawled along the bottom of the seas. Trilobites - a kind of arthropod - roamed along with them.

During this period, the average global temperature probably increased. Temporary shallow seas are common.

And one of the most important events in prehistory occured - the appearance of widespread land plants. These plants would go on to form coal deposits in other parts of the world, however in Gondwana, Devonian coal deposits are unknown. A few plants are known from Devonian Gondwana, but land plants possibly did not develop on Gondwana - rather one of the northern continents of Siberia, Laurussia, Kazakhstania or China, and as Gondwana was geographically isolated from these continents, they possibly did not spread there as widely as in other places during the Devonian.

The populations of marine invertebrates were rich and diverse on Australia during the Devonian, possibly as a result of the warm climate. Groups of fish such as lungfish and "placoderms" (armoured fish) existed in Australia during the Devonian. So did many kinds of "chondrichthyan" (cartilaginous fishes, like sharks and rays).

Griphognathus, one kind of lungfish, had a deep vertically flattened fish body and a duck-like snout that it used to forage for food in the seabed. As for placoderms, there were arthrodire placoderms similar to the huge Dunkleosteus of the Northern Hemisphere, including a three-metre relative called Westralichthys. These arthrodire placoderms had extensive armour over the front of their bodies, and instead of teeth their armour became jagged-edged over the mouth to form big biting devices.

As well as the arthrodire placoderms, there where the odd-looking antiarch placoderms such as the freshwater fish Bothriolepis. Like the arthrodires, the antiarchs had extensive armour covering over the front of their bodies. But antiarchs took it a step further by having the first pair of fins - the pectoral fins - covered in armour as well.

Amphibians, the first tetrapods (groups that include all land animals - i.e., not fish), are known to have existed in Australia during the Devonian. In fact, the earliest known trackways of tetrapods from anywhere in the world were discovered in Victoria, from the early Devonian. Amphibians are divided into at least three groups. One of these groups are the "labyrinthodonts" - in Australia this included things called ichthyostegalians and temnospondyls. The temnospondyls were more common.

The Eary Carboniferous was relatively warm, and huge forests of trees and other plants had appeared. Ancient coal-forming plants are known from Carboniferous Australia.

Worldwide news: Reptilian tetrapods evolved from amphibian tetrapods, and the first reptile fossils appear in the early Carboniferous. These animals and all their descendants (including us) are known as "Amniotes", for the hard eggs (as opposed to amphibian eggs) that could be laid on land rather than being restricted to water. They also developed thick skin for retaining moisture, so they could venture further from water sources. Amniotes where the next logical step for vertebrate animals spreading onto land - designed for dryness.

The amniotes where divided into the "synapsids" and the "sauropsids" - most land vertebrates that are not amphibians are either synapsids or sauropsids. Humans: put your hand to your temple, on the side of your skull. That temple makes you a synapsid. Both the synapsids and the sauropsids mainly included little lizard-like animals during the Carboniferous.

Thicker air than we have today ensured that giant insects (like the enormous dragonfly Meganeura) could stay in the air.

During the later Carboniferous, Gondwana had moved again, and the Australian sector of Gondwana shifted far south. This, of course, resulted in much cooler conditions, and the advance of glaciers. Glaciers are huge masses of ice, such as that covering Antarctica nowadays, although Carboniferous Australian glaciers were not so extensive: they stayed mainly on the highland areas and on islands off the East Coast.

The Western areas were still somewhat warm, but becoming progressively cooler towards the end of the period.

During the Permian, the synapsids (one of the two major groups of amniotes) evolved into some of the very first large land animals! At first they included creatures known as "pelycosaurs", fat stocky creatures with sprawling legs that included herbivores with little heads and huge barrel-like bodies, and carnivores with smaller bodies and bigger heads full of sharp teeth.

Then came the "dinocephalians", who had tight rows of teeth and heads shaped almost like footballs that angled downward. Most of the dinocephalians where huge, heavy herbivores (like Moschops), while others where carnivores (like Anteosaurus).

Then there were also the "therapsids", generally smaller than the dinocephalians and the pelycosaurs with more dog-like bodies. Their heads where much flatter. They are our ancestors.

The synapsids where definitely the largest land animals around. Their sister group, the sauropsids, hung around mostly as small reptiles.

In Australia, glaciation (resulting from that part of Gondwana shifting into polar areas) had not subsided by the beginning of the Permian. Rather, it grew in extent.

True glaciers covered huge areas of the continent, mainly in the East. A major ice sheet covered New South Wales, Northern Territory, Soth Australia and Victoria. It appears to have extended up out of other areas of Gondwana, such as Antarctica, further south.

281mya, the extent of glaciation started to fall. By about 267mya, the glaciation in the west had mostly gone. And glaciation in the Australian region of Gondwana finished completely in the late Permian.

Most of Gondwana still lay around in very far south latitudes, including Australia, so continental drift does not account for the dissappearance of glaciers. What does is the onset of widespread (possibly global) warming. There was also plenty of rainfall after the glaciers had left. This fueled the spread of plants in Australia. Vegetation was probably abundant, and many coal deposits date from the late Permian.

Continental drift was bringing ALL the major landmasses together during the Permian. Siberia, China, and Kazakhstania, along with the larger continent Laurussia, and the even bigger landmass of Gondwana, came together to form the "supercontinent" known as Pangaea.

The effect of the continents joining together should have been ecologically dramatic - as fauna and flora from all the different landmasses would now be able to mix with each other. Perhaps it is this that led to a major event in the history of life on Earth, around the end of the Permian period: the Permian extinction, during which - worldwide - 90% of the species of the time that we have a fossil record for became extinct.