Mary Allen
The Palaeozoic is a period in the history of the earth. It began about 540 million years ago and ended about 250 million years before our time. It is therefore a section of almost 300 million years.
The Palaeozoic is divided into different periods:
- The Cambrian 540 to 485 million years ago,
- the Ordovician 485 to 443 million years ago,
- the Silurian 443 to 420 million years ago,
- the Devonian 420 to 359 million years ago,
- the Carboniferous 359 to 300 million years ago and
- the Permian 300 to 250 million years ago.
Scientists also call it the Palaeozoic Era. The word comes from ancient Greek and can be translated as “ancient creatures”. The Mesozoic era, in which the dinosaurs lived, followed the Palaeozoic. Our current time is called geologically the Cenozoic Era.
How did the continents change?
The world looked very different then than it does today. At the beginning of the Palaeozoic, the earth was covered in the very south by a huge landmass: Gondwana. Much of this continent was covered by ice. Its northernmost foothills, however, reached as far as the equator. There were also three smaller continents in the tropics, just south of the equator. Where Europe is today, there was then an ocean. Over the course of millions of years, the continents moved further north.
About 400 million years ago, the arrangement of the continents changed significantly. Two of the smaller continents collided. The continent of Laurussia was formed. When these two land masses met, mountains formed, some of which still exist today. These include, for example, the Appalachians, a low mountain range in the USA and Canada. Later still, the other great continent Gondwana moved further north and collided with Laurussia. This is how the huge continent of Pangea was formed. Pangea was a so-called supercontinent because it was the only continent at the time.
How did living things evolve in the Palaeozoic?
At the beginning of the Palaeozoic was the Cambrian. At that time, the animals still lived exclusively in the water. It was mainly sponges, corals, snails, and cephalopods. There were already the first animals that had a hard skeleton or shell. The flora was mainly limited to algae. The land surface was bare and plantless.
In the next period, the Ordovician, the first land animals, and plants appeared near the shore. These were mainly amphibians, i.e. animals that lived partly in water and partly on land. There were also the first animals with eyes. Especially in the Devonian animals and plants spread increasingly over the land, especially insects. But many new species also emerged in the sea. These included, for example, the ancestors of today’s sharks.
The first reptiles appeared on land in the Carboniferous period. Animals laid their eggs on land. There were large insects like the giant dragonfly. A large part of the earth’s surface was already covered by forest. In the Permian period, most of the aquatic animals of that time became extinct. On land, however, life continued to develop. Reptiles began to split into herbivores and carnivores. Among the plants, there were the first conifers.
At the end of the Permian, 250 million years ago, there was severe climate change. It was caused by enormous volcanic eruptions in present-day Siberia. The result was the largest mass extinction in natural history to date. Twice as many species disappeared as when dinosaurs went extinct 65 million years ago.