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6 million years hence, Mid Recurocene
6 million years have passed since man's disappearance. This is a mere blink in the geological time scale, and so animals are overall not very different from their Holocene ancestors, but nonetheless this is a changed world. For the last 6 million years, the earth has retained a glacial, dry climate, the only relief from these conditions being the short interglacial cycles that would appear every 100,000 years or so, bring warm conditions for around 10,000 years, before the earth plunges back into another glacial period. It is currently the middle of one of those long glacial periods, with expansive ice sheets covering the poles and dominating large areas of the northern hemisphere, bringing cool, dry temperatures worldwide.
Australia lacks ice sheets aside from a few glaciers on its highest peaks, with the New Guinean portion being well over the equator the continent is now well and truly in tropical latitudes. Varied landscapes ranging from lush floodplains and rainforest to harsh deserts of spinifex and chenopods provide all sorts of opportunities for animals to exploit, all the while the proximity of Australia to Asia becomes ever more apparent as the island continent creeps north.
Geography overview
Geography overview
It may have been only 6 million years, but Australia's a quick little mover, one of the fastest of all continents. It is already becoming dangerously close to the Asian subcontinent of Sunda, continuing to push up thousands of islands between them, from which animals can island hop across. Interchange with Asia is becoming increasingly easy, and will continue to do so as Australia marches ever closer towards the northern continent. Along the way it has collided with several islands, like Timor, Flores, Komodo, Sulawesi, New Britain and Ireland, and many others. Some of these islands house a large amount of Asian flora and fauna, which has now spread into Australia and begun to diversify, furthering the influence of Asia on the ecology of the continent.
With a glacial cycle in full swing, Australia is at its full extent. Dry land is exposed from New Guinea to Tasmania, and land extends several hundred kilometres to the edge of the continental shelf, where the land drops off swiftly into deep sea. The oceans have now recovered from the extremes of climate change that impacted them so strongly, so much so that coral reefs once again grow in the shallow areas on the edge of the shelf across the north of the continent, and mangrove swamps occur in large groves along the shore where suitable conditions occur. As Australia moves north it will begin to cut off the rich currents that are responsible the biodiverse conditions in the seas of northern Australia and adjacent areas of south-east Asia, but for now these fertile waters are home to an enormous diversity of marine life.
While the Recurocene has a very similar level of glaciation, desert is not as expansive in Australia as in the Pleistocene. This is to do with Australia's movement into warmer, more tropical latitudes, which has resulted in the north of the continent becoming covered in rainforests and floodplains. Wet forests also extend down the east coast, following the mountains all the way down to the Tasmania, as they do today. However, once you pass the Great Dividing Range and head west into the interior, the change is palpable. With rain blocked by the mountains, the wet forests thin out to be replaced by grasslands and dry woodlands. The terrain becomes increasingly arid the further you head west, until you finally reach the dusty plains of spinifex, chenopods and Mitchell grass that dominate much of the continent. This is a land of extremes, a place where the temperature may swing from 35 degrees Celsius to below zero in only twenty-four hours, and rainfall is both very scarce and completely erratic. Although it may be getting wetter as it moves north and out of the horse latitudes, these arid plains still cover nearly 60% of Australia's land area, providing both challenge and opportunity for species trying to make a living in the inland.
With tectonic pressure becoming ever more strenuous, the north is becoming subject to increasingly strong geological activity. The mountains of New Guinea, by far the highest in all of Australia, are continually being pushed higher and higher, and several peaks are now above 5,600 metres. There has also been a surge in volcanic activity, with active volcanoes now dotting the north coast as pressures continue to build. These create a significant environmental hazard that wildlife in their vicinity has had to learn to cope with.
Faunal overview
Faunal overview
Australia was once home to a menagerie of strange, huge creatures known as megafauna, the giants of the Pleistocene. In the end, their size was their undoing, as they all disappeared soon after human arrival, unable to cope with drastic habitat modification and increased hunting pressure. This left a continent of smaller creatures, the largest native mammal being no larger than a man. However, now that man has gone and glaciation has returned, the conditions that led to the evolution of these giant beasts have reappeared. A new age of giants has dawned, and Australia is home to a variety of megafauna once again, descended from both native and foreign species.
As mentioned earlier, Australia has now collided with several Asian islands, and has gained several new Asian groups as a result. In terms of new placental families, the collision with Timor 5 million years ago brought shrews to Australia's northern shores, while the more recent collisions (2-1 million years ago) of Flores, Komodo and Sulawesi has given macaques, tarsiers, bovines and viverrids an early start on the Australian scene. Additionally, birds and bats continue to fly between Australia and Asia, while tree shrews, chevrotains and a few new rodents have managed to island hop their way over from mainland Asia, and a small dasyurid has recently arrived in the forests of Sunda, the first marsupial to ever set foot on continental Asia.
While it is now beginning to fill up with several groups of ungulates, with suids, bovids and two families of deer all being present, Australia's most diverse and successful group of herbivores continues to be the macropods. The continent's greatest evolutionary product since the Passeri songbirds, their form of locomotion is far more efficient than any other mammals their size, and their adaptions to aridity are much more complete than those of their placental competators, leaving the inland theirs to conquer. However, cervid deer also have a strong presence in the forests of the east and north, where they have partitioned niches with the macropods, which are primarily grazers while the deer specialise in browsing. Although less successful than macropods, another group of herbivorous marsupials, the possums, have also diversified, most prominently in western and inland Australia where they lack the competition of ungulates.
In terms of mammalian carnivores, two families are particularly notable, the Canidae and the Felidae, both of which have diversified into Australia's dominant predators over the last 6 million years, now ranging from the size of a raccoon to that of a bear. Meanwhile, the dasyurids, Australia's marsupial carnivores, have largely lost the evolutionary arms race to their placental contemporaries in terms of being large, dominant predators, and have instead continued doing what they do best, being small, and remain widespread and diverse in their typical shrew-like forms. However, the last hurrah of the large marsupial carnivores still hangs on in the forests and mountains of south-east Australia. Viverrids are a recent arrival and currently restricted to the northern rainforests like most of the island migrants. In terms of reptilian carnivores, varanids, crocodilians and pythons continue to be significant predators, and huge raptors are apex predators in several ecosystems.
This is of course only a very shallow, brief look at the fauna of Australia at this time, only showcasing faunal interchanges and some of the niche partitioning between megafaunal herbivores and carnivores. It is time to take a closer, more in-depth look at mid Recurocene Australia, and observe its varied landscapes, ecological dynamics and local inhabitants. It may not be a far future, but here on the continent that never rests, change is already taking hold.
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