Proterozoic era, which lasted about twobillion years, played an important role in the formation of the world, as we know it now. This longest geological period, which occupied almost half of the total history of the planet, was marked by a series of epochal events that turned back the Earth evolution.
It is the Proterozoic era that was noted.the increase of water masses in the hydrosphere so that the first seas began to merge into a single ocean of a planetary scale, the level of which eventually reached the tops of oceanic ridges. This first tectonic-geochemical frontier was marked by a sharp increase in the degree of hydration of the oceanic lithospheric crust (due to the excessive saturation of the rift zones with large masses of saline ocean water). This process lasted about six hundred million years. And it played a crucial role in the subsequent formation of the ocean floor topography.
На смену самому древнему историческому этапу, Archaea, came the Proterozoic era. The climate with the beginning of a new era began to change significantly. The surface of the planet, which in the Archean period was practically a bare cold and lifeless desert with frequent glaciations, underwent significant changes (towards warming) closer to the middle of the Proterozoic.
Then there was a significant saturation.atmospheric oxygen, which radically changed the direction of the evolutionary development of biological organisms. Scientists have already called this fateful event about two billion years ago an “oxygen catastrophe.” This period is characterized by the emergence of the first single-celled aerobic organisms (since the oxygen concentration in the air mixture was sufficient to ensure their vital activity). It was then that most species of anaerobic organisms became extinct, for which molecular oxygen turned out to be lethal. That, to a considerable degree, predetermined the further vector of evolutionary development.
During this gigantic time intervalmicroorganisms and algae flourished. Rather intensive processes of formation of almost all sedimentary rocks, which marked the Proterozoic era, proceeded with the direct (and very active) participation of these life forms.
Eukaryotes, ousted from the evolutionary scene"Retarded" prokaryotes, too, were formed when the Proterozoic era came. Animals breathing air, by the way, appeared on the planet in the same historical period. Most species of the fauna of the Late Proterozoic era have already been represented by multicellular eukaryotic forms. The end of this era may well be called the "century of jellyfish", which then prevailed on the planet. At the same time, annelids (progenitors of mollusks and arthropods) appeared.
The Proterozoic era was grandiose.the duration of the historical period during which began the undivided rule of the eukaryotic cell. Primitive unicellular and colonial life forms began to be replaced by multicellular highly organized creatures. Life itself has become an important factor in geological evolution. Living organisms began to take an active part in changing the composition and shape of the earth's crust, they became the basis of its upper layer - the biosphere. On Earth came photosynthesis, the value of which can not be overemphasized. It was he who so altered the composition of the atmosphere, filling it with a huge amount of oxygen, which made possible the development of higher heterotrophic organisms - highly organized animals.
Thus, optimal conditions were created forthe arrival in this world of the highest form of life - a man who was destined to change the face of the planet in a short moment of its existence (only 500 thousand years - one moment by the standards of geology!) beyond recognition. And at the same time, to give the concepts of "life" and "evolution" a completely new meaning ...
