Palaeozoic

The Paleozoic era is a fairly long stage of the Earth's development. It lasted 370 million years.

After the formation of significant areas of land at the end of the Proterozoic era, the Paleozoic era began with a vast spill of seas. According to many geologists, at that time there was one huge continental block, which is called Pangea ("all land" in the translation from the Greek language). From all sides it was surrounded by the World Ocean. Over time, this huge block has disintegrated. Thus, the Paleozoic era became the time of the formation of the foundations for future continents. During the further development of the Earth, these parts could increase, connect (due to the mountain-forming processes) or decrease, falling apart again into pieces, which could be separated from each other until they occupied the position of the present continents.

The first hypothesis about "continental drift" was expressed by Alfred Wenger (German geologist). In his opinion, initially Pangea split into Gondwana and Laurasia.

Periods of the Paleozoic era are divided into Permian, Carboniferous, Devonian, Silurian, Ordovician and Cambrian (the most ancient).

The Cambrian stage began about 570 million years ago (according to some sources, somewhat earlier). The duration of this period is 70 million years. The beginning of the stage is connected with the evolutionary explosion on Earth, as a result of which the first representatives of most of the main animal groups that are known today appeared.

The Precambrian and Cambrian boundary is noted in the rocks, where a huge variety of animal fossils with mineral skeletons unexpectedly appears. Cambrian evolutionary explosion is one of the mysteries of the history of the development of the planet. For the transition of the simplest cells into eukaryotic (more complex) it took two and a half million years. After 700 million years, the first multicellular organisms appeared. And for another 100 million years the planet was inhabited by an incredible variety of animals. It should be noted that since that time (more than 500 million years) no animal has appeared on Earth, which has a fundamentally new structure of the body.

Ordovician period about 500 million years ago began, and ended - about 408 million years ago.

Most of the southern hemisphere was occupied by Gondwana. Other large areas of land were concentrated in the equatorial zone. The sea at that time was inhabited by numerous animals, very different from the inhabitants of the seas of the Cambrian. The land was practically unsuitable for life - there was neither soil nor plants, the sun burned mercilessly, often there were hurricanes and volcanic eruptions.

By the end of the Ordovician stage, they began to select on the coastal mud, decomposing it, communities of fungi, algae, bacteria. Thus, a primitive soil layer was formed.

At the beginning of the Silurian period, the fish took shape, close to the modern. By the end of the stage, the mountain-building processes begin. As a result formed Cambrian, Scandinavian mountains, as well as massifs in Eastern Greenland and South Scotland.

The Devonian stage of the Earth's development is characterized by the greatest cataclysms on the planet. At that time, there was a clash of Greenland, Europe and North America. Formed a huge continent of Laurasia.

The Carboniferous period (carboniferous) was characterized by a diverse climate - changes occurred from century to century. However, in general, it (the climate) was characterized by high humidity of the temperate, subtropical and tropical belt. This created favorable conditions for the spread of marsh and forest vegetation on land.

Life in the Paleozoic era was formed quite actively until the end of the last stage.

299 million years ago the final stage of the Paleozoic began. At the border with the Triassic period, the largest extinction of species occurred in the history of the planet. At that time about 70% of terrestrial and about 90% of marine organisms disappeared. Thus ended the Paleozoic era.