“Australia. A Continent Adrift” full documentary in which we discover how animals that populated this part of the supercontinent Gondwana have evolved as to what the Australian continent adrift in the ocean.
The story of the inhabitants of this Terra Australis can be traced back to the distant days when all the continents of the southern hemisphere were one. The world was then a warmer, and more humid place, in which enormous dinosaurs ruled over a zoology in permanent evolution. The remains of that universal jungle can still be seen in the north east of Australia, and are now home to the descendents of the long extinct dinosaurs.
The birds are the most numerous species in this green, suffocatingly humid world. Their ability to fly meant they were not condemned to isolation like the land creatures of Australia, and competition with the species from the rest of the world produced new types of bird, which then came to these Jurassic forests, and stayed forever.
In those distant forests, one hundred million years ago, there lived different types of mammals who sought to ensure their survival by using different means of reproduction. The monotremes, the oldest of all, were mammals, but laid eggs; the eutherians gave birth to completely developed young; and the marsupials, somewhere between these two extremes, completed their development outside the mother’s body.
The jungles of South America were, like those of Australia, once part of Gondwana. Back then, monotremes, marsupials and eutherians coexisted in the primeval forests. But the last of these three, little by little, gained ground, as their new evolutionary prototypes improved.
The new mammals not only had placentas, they were also more intelligent, and they took over the majority of the habitats of the monotremes and the marsupials. But defeat was not quite as absolute as people tend to think. Because, in the South American night, old ghosts from Gondwana still hide.
Everything began with a great journey across the Indian Ocean, millions of years ago.
This was just the beginning of the great marsupial adventure, a period of enormous changes.
On its journey northwards, Australia became increasingly warm, and its jungles became smaller. The climate of the island slowly changed. The plants had to adapt or die. Each change in the climate meant a change in the vegetation, and each one of these was followed by an endless number of adaptations by the animals.
And Australia continued moving north on its slow journey across the Indian Ocean.
The closer it came to the Tropic of Capricorn, the more temperate the climate became. Where once there had been jungle, vast open plains appeared The pasture took over the land, and new colonists appeared, some of them close relatives of those who still now live hidden in the last remaining jungles of Australia.
The trees of the jungle were always a place of refuge and expansion for the marsupials. As foliage became sparser, due to climate warming, they were forced to colonise the plains and grasslands.
The koala was able to colonise the eucalyptus forests thanks to an adaptation which would seem impossible – the ability to feed on its leaves. The leaves of the eucalyptus tree are a combination of low-quality food, indigestible material, and active poisons. Any animal that could adapt and make use of these leaves would have absolutely no competitors. And that is precisely what the koala did.
The koala is an example of the incredible versatility of adaptation of the marsupial mammals of Australia.
The duckbill platypus is one of the three species of monotremes mammals that lay eggs, a shy animal which lives in some rivers in the east of Australia. The other two are echidnas the long-snouted variety in New Guinea, and this one, the short-snouted variety, which can be found throughout Australia.
Australia continues on its slow drift northwards, at a speed of six centimetres a year.
At present, a narrow strait is all that separates the fauna of the two continents. But what will happen when the animals of Asia and Oceanía come into direct contact? There may well be enormous upheavals in the uncertain future of this continent. It is easy to image that the evolution of its landscapes and animals will undergo far-reaching changes. But, probably, when new, specialised creatures adapt to the unique conditions of these forests or deserts, causing many of the evolutionary prototypes that now dominate Australia to die out, in the farthest depths of the jungle, with their pacific and archaic way of life, there will continue to be echidnas and duckbill platypuses. And, as in Gondwana in the distant past, there will continue to be mammals who lay eggs.
