Pubblicato da: rainbowman56 | 28 settembre 2011

A bit of prehistory.

Everyone knows the prehistory of the mind in which the dinosaurs disappeared about 65 million years. But few people know another story even more fascinating and more importance for what is life on land, but especially and more specifically, to us humans. It was not an isolated event but a chain of events, a struggle between forces of evolution among prehistoric creatures that ended with one victor, our ancestor ……… The story begins:


500 million years ago.

So far life in the prehistoric seas, oceans before the beginning of the Cambrian period,
consisted of single-celled or multicellular creatures (many
cells, but all the same) soft body, which they obtained their food by filtering the water around them, or feeding on bacterial mats (dense colonies of bacteria) on the ocean floor.

I will not go into details but then gave a very important place, which is known as the Cambrian Explosion, say it is from this date (500 thousand years) when the three-edged mother will result in all other species we know and that interaction

between them, set up, the situation now is the arthropods, molluscs and vertebrates (the group we belong to).

Well, at that time, life beyond the seas was unknown, and the seas and oceans were then inhabited by beings of strange shapes as the famous trilobites and other less friendly as Anomalocaris (left) or Hurdia Victoria (the latter were the top predators of the time). These three species were among the arthropods. The dominant and most numerous group that reigned on molluscs (its variety was insignificant) and vertebrates.

In fact, the Cambrian vertebrates were a small and unimportant. For example, while Victoria Hurdia reach 50 cm or up to one meter Anomalocaris, the
representative of the larger vertebrates that was Pikaia (pictured right) did not exceed 5 cm
length. Come on, that our ancestor was a true miniature land of giants.

The pikaia our ancestor, was long, small, light having a backbone instead of shell but it was also the major arthropod prey. He devoted himself to hide in the care of arthropods and eat the waste and the remains of prey left by large predators battleships were mainly scavengers.

Nothing seemed likely to change, the arthropods dominate the land and seas over the millennia, eating and leaving decimated vertebrates, thus reducing the possibility of not only our species but also birds, dinosaurs, fish and other mammals, may appear in the future. But conditions changed.

450 million years ago.

In the late Ordovician period (the next to the Cambrian period) was the second largest extinction of life on Earth history, eliminating 85% of the species.

A global ice age that froze oceans and seas

covered them with a blanket of 800 meters of ice and snow had catastrophic consequences for the life of this era. The lack of light and the intense cold was killing larger species and more specialized, bone arthropods. This led to the other two groups (vertebrates and molluscs) may develop: vertebrates evolved and appeared larger scavengers such as conodont (about 10 cm, right image). But they were vertebrates which rose to the position of the dominant group, but molluscs. The supremacy of vertebrates was cut again, but in this case by the large mollusks.

Now the predators were large molluscs such as Ortocono (left)
and Nautiloidea. And they dominated the other groups until they took another step, one giant leap in the way of the evolution of arthropods came ashore.
On land they had no predators, and eventually took the opportunity to grow and multiply. There were big and strong and the seas again to reconquer. And they succeeded. Arthropods were Jaekelopterus rhenaniae most important ancestors of scorpions and giant like Pulmonoscorpius.

Over time, the move gave them the advantage on mollusks to arthropods and vertebrates (leaving ground) would also be a fatal mistake that would destroy them.

375 million years ago.

Gradually, over the millennia, vertebrates were going to land, a land that was populated with a number of plants that helps to oxygenate the atmosphere and produced the right conditions for our ancestors to develop.
Shellfish centuries ago who had returned to background. In contrast, on land, vertebrates were developed only arthropods and began to exceed the size, strength or agility of the arthropods. The last battle was about to begin.

On the one hand were the arthropods were strong but had a weakness: its outer armor. They had to grow as the animal grew. If the animal was too big armor, and thus increasing the animal’s weight. Could weigh as much that came a moment that was counterproductive in an evolutionary sense. At best, could reach a size of 3 meters.

On the other side were the vertebrate ancestors. Animals that could grow larger without becoming too heavy to be sustained. Vertebrates, thanks to its design, its backbone, they could better adapt, develop better, evolve … and all this without becoming heavy tanks.

250 million years ago.

The reign of the arthropods are gone forever. And with this came the dinosaurs, birds, fish … y.

.. us HUMANS.


  1. Howdy! Do you use Twitter? I’d like to follow you if that would be ok. I’m absolutely enjoying your blog and
    look forward to new updates. This has been very much appreciated information!


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