And the Mammals Laid Eggs

2004, Nature  -  52 min Leave a Comment
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In 1798 the zoologists of the British Museum in London met to examine the skin of an extraordinary animal, which had been sent to them from New South Wales by a colonist called Dawson. That animal was completely different from anything they'd ever seen before. Its fur was like that of an otter, it had webbed feet like a duck, a flat tail like a beaver and in place of a mouth a duck's bill. Those experts declared Dawson's animal to be an elaborate hoax, but in reality it was just one example of an entirely different wildlife.

Millions of years of isolation had made it possible for a process of parallel evolution to take place in Australia. Ancient groups of mammals who had tried their luck in the fight for survival had almost entirely disappeared from the other continents. While alone on this enormous island in the Southern Hemisphere, they were able to diversify far away from their better equipped competitors.

Australia separated from the rest of the world became a gigantic Noah's Ark, where those original inhabitants of Gondwana, the super continent which contained all the lands of the Southern Hemisphere were able to prosper. Here, life evolved along different lines and the continent of Australia became home to unique zoological species. The fish experimented with lungs. The birds grew to almost two meters, the trees became fire resistant... and the mammals laid eggs.

The story of the inhabitants of this land can be traced back to the distant days when all the continents of the Southern Hemisphere were one. Dense rain forests covered the edges of the super continent, Gondwana. The world was then a warmer and more humid place in which enormous dinosaurs ruled over zoology and permanent evolution. Alongside the enormous prehistoric dragons, protected within the jungles lived other smaller, more recent creatures waiting for the climatic changes, which would prove to be an insuperable obstacle for the powerful lizards.

The remains of their universal jungle can still be seen in the Northeast of Australia and are now home to the descendents of the long extinct dinosaurs. The birds are the most numerous species in this green, sufficatingly humid world. Their ability to fly meant that 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.

Here there were no large predators and food was plentiful. So many species of birds became part of the history of this independent evolution giving rise to extraordinary creatures. The Cassowary is one of the heirs to the gigantic birds which inhabited the jungles of Gondwana. Those common ancestors evolved into the Ostriches in Africa, the Rheas in South America and the Emus and Cassowaries in Oceania.