Around 35 million years ago, the continent of India meets up with the Euroasian continent. From 25 million years ago to the present, India will push north against the larger continent to form the Himalayan mountains and with it the highest mountain in the world — Mount Everest. The existence of these mountains would help to change the climate to the west in places like the Middle East and northern Africa to one which would receive less rain and possibly, with enough time, become a desert. (1)

As these geological events were happening, there came into existence two evolutionary branches from the Purgatorius primate. One species evolved into very primitive monkeys that were to lead to modern apes such as Chimpanzees, while the other became primitive ape-like primates living on open savanna country.

The reason for the ape-like primates moving out of the wetter tropical regions and into the drier, harsher and less-protected grasslands of the savannas is not fully understood. However, some scientists believe it may be because of the many individual primate groups of the forest competing for food (perhaps some primates had already gone back to the rainforests as the climate in some parts of the world began to dry up).

If this is true, it is quite conceivable that such an explorative and more curious group would have eventually expanded outwards in the hope of finding a better life if it wished to maximise its chances of survival.

Or perhaps the natural climate change was already forcing some primates to adapt to the savannah?

In the meantime, all the modern animals of the twentieth century had their origins nearly 36 million years ago. In other words, if you could travel back in time and look around on the great continents of the world, you will notice many familiar animals of today (give or take a few minor changes in appearance).

 
Africa pushes against Europe starting the building of the Swiss Alps.

 
A number of mammals have grown in size to become the largest of its type in all the continents of the world (including Australia). They would never reach the size of those reptiles called the dinosaurs, but compared to the animals of our times, these were big creatures.

For example, the ancestors of whales were at one time no bigger than a small horse with sharp teeth, four small legs and a tail, and had a thin fur on their skin. But they later grew into the biggest warm-blooded predators in the oceans weighing up to 60 tonnes and 4 times longer than a fully grown adult great white shark of this era.

Actually the shark species nearly 25 million years ago were at least twice as large as the biggest modern day great white sharks. Evidence for this observation can be found in the massive fossilised shark tooth collected from the Tasman sea floor in 2003 by CSIRO marine research scientist Dr Alan Williams during the joint Australia-New Zealand NORFANZ research expedition (2).

However, as food supplies dwindled in the cooler oceans of the world and along the shoreline, these massive predatory whales would eventually die out, leaving behind a handful of other whale species with better survival rates because of their greater reliance on alternative food sources such as plankton.