Geological History

From the Ordovician period to the Silurian period

After the Cambrian age, described in Highlight 1, evolution progressed slowly at first in the Ordovician age. 

490 - 443 million years ago, all life happened in the sea. It was the time of primitive corals, sea cucumbers, starfish and seashells, and of arthropods, especially trilobites, the primitive scorpions. And the first large predators were cavorting in the seas, such as giant squid which were up to 10 metres long.

At that time, the only vertebrates were primitive, jawless fish, and on land the first slime moulds and lichens were developing.

Evolution also didn’t take time off in the Silurian age 443 to 417 million years ago. Arthropods ruled the seas, giant scorpions made excursions to the land, primitive fish protected themselves from large predators with armour and very good sensory organs. Plants and fungi now grew along rivers and streams, although they barely reached 10 cm in height.

In the Devonian Age, 417 to 354 million years ago, evolution took a giant step forward.

The first forests formed on land, consisting of primitive trees called Archaeopteris, which were very similar to today's conifers. The first vertebrates, such as the amphibian Hynerpeton, also appeared on the scene. In turn, three new species of fish appeared in the sea that were to drastically change the rules in the game of evolution.

First came the cartilaginous fish. Fast and agile, they became very successful predators. Their most famous representative still exists today: the shark. Then there were the placeoderms, the armoured fish, to which the super predator Dunkleosteus belonged. And as a connecting link, the bony fish emerged, which also reached enormous dimensions in the Devonian and are the ancestors of most living fish today.