And the universe. For example, the hypotheses of Kant - Laplace, O.Yu. Schmidt, Georges Buffon, Fred Hoyle and others. But most scientists tend to believe that the Earth is about 5 billion years old.

The unified international geochronological scale gives an idea of ​​the events of the geological past in their chronological sequence. Its main divisions are the eras: Archean, Proterozoic, Paleozoic, Mesozoic. Cenozoic. The oldest interval of geological time (Archaean and Proterozoic) is also called the Precambrian. It covers a large period - almost 90% of the entire (absolute age of the planet, according to modern ideas, is taken equal to 4.7 billion years).

Within the eras, smaller time intervals are distinguished - periods (for example, the Paleogene, Neogene and Quaternary in the Cenozoic era).

In the Archean era (from the Greek - original, ancient), crystalline rocks (granites, gneisses, schists) were formed. In this era, powerful mountain-building processes took place. The study of this era allowed geologists to assume the presence of the seas and living organisms in them.

The Proterozoic era (the era of early life) is characterized by rock deposits in which the remains of living organisms are found. During this era, the most stable areas, platforms, formed on the surface of the Earth. Platforms - these ancient cores - became the centers of formation.

Paleozoic era (era ancient life) is distinguished by several stages of powerful mountain building, . In this era, the Scandinavian mountains, the Urals, Tien Shan, Altai, Appalachians arose. At this time, animal organisms with a solid skeleton appeared. Vertebrates first appeared: fish, amphibians, reptiles. Ground vegetation appeared in the Middle Paleozoic. Tree ferns, club mosses, and others served as material for the formation of coal deposits.

Mesozoic era (era average life) is also characterized by intense folding. Mountains formed in areas adjacent to. Reptiles dominated among animals (dinosaurs, proterosaurs, etc.), birds and mammals first appeared. The vegetation consisted of ferns, conifers, angiosperms appeared at the end of the era.

In the Cenozoic era (the era of new life), the modern distribution of continents and oceans takes shape, and intense mountain-building movements take place. Mountain ranges form along the coast Pacific Ocean, in the south of Europe and Asia (, the Himalayas, the Cordillera Coast Ranges, etc.). At the beginning of the Cenozoic era, the climate was much warmer than today. However, the increase in land area due to the rise of the continents led to a cooling. Extensive ice sheets appeared in the north and. This led to significant changes in the flora and fauna. Many animals have died out. Plants and animals appeared close to modern ones. At the end of this era, man appeared and began to intensively populate the land.

The first three billion years of the development of the Earth led to the formation of land. According to the ideas of scientists, at first there was one continent on Earth, which subsequently split into two, and then another division took place, and as a result, five continents have formed by today.

The last billion years of the Earth's history is associated with the formation of folded regions. At the same time, several tectonic cycles (epochs) are distinguished in the geological history of the last billion years: Baikal (end of the Proterozoic), Caledonian (early Paleozoic), Hercynian (late Paleozoic), Mesozoic (Mesozoic), Cenozoic or Alpine cycle (from 100 million years to the present).
As a result of all the above processes, the Earth acquired a modern structure.

Hello! In this article I want to tell you about the geochronological column. This is a column of periods of the Earth's development. And also more about each era, thanks to which you can draw a picture of the formation of the Earth throughout its history. What types of life first appeared, how did they change, and how much did it take.

The geological history of the Earth is divided into large intervals - eras, eras are divided into periods, periods are divided into epochs. Such a division was associated with events that took place on. The change in the abiotic environment influenced the evolution of the organic world on Earth.

Geological eras of the Earth, or geochronological scale:

And now about everything in more detail:

Designations:
eras;
periods;
Epochs.

1. Catharchean era (from the creation of the Earth, about 5 billion years ago, to the origin of life);

2. Archean era , the most ancient era (3.5 billion - 1.9 billion years ago);

3. Proterozoic era (1.9 billion - 570 million years ago);

Archean and Proterozoic are still combined into Precambrian. The Precambrian covers the largest part of geological time. Formed, areas of land and sea, active volcanic activity took place. Shields of all continents were formed from Precambrian rocks. Traces of life are usually rare.

4. Palaeozoic (570 million - 225 million years ago) with such periods :

Cambrian period(from the Latin name for Wales)(570 million - 480 million years ago);

The transition to the Cambrian is marked by the unexpected appearance of a huge number of fossils. This is a sign of the beginning of the Paleozoic era. Marine life flourished in numerous shallow seas. Trilobites were especially widespread.

Ordovician period(from the British Ordovician tribe)(480 million - 420 million years ago);

On a significant part of the Earth it was soft, most of the surface was still covered by the sea. The accumulation of sedimentary rocks continued, mountain building took place. There were reef builders. An abundance of corals, sponges and molluscs has been noted.

Silurian (from the British Silur tribe)(420 million - 400 million years ago);

Dramatic events in the history of the Earth began with the development of jawless fish (the first vertebrates), which appeared in the Ordovician. Another significant event was the appearance in the late Silurian of the first terrestrial.

Devonian (from Devonshire in England)(400 million - 320 million years ago);

In the early Devonian, mountain building movements reached their peak, but basically it was a period of spasmodic development. The first seed plants settled on land. A great variety and number of fish-like species was noted, the first terrestrial animals- amphibians.

Carboniferous or Carboniferous period (from the abundance of coal in the seams) (320 million - 270 million years ago);

Mountain building, folding, and erosion continued. IN North America and the flooding of wetland forests and river deltas occurred, large coal deposits formed. The southern continents were covered by glaciation. Insects spread rapidly, the first reptiles appeared.

Permian period (from the Russian city of Perm)(270 million - 225 million years ago);

A large part of Pangea - the supercontinent that united everything - was dominated by conditions. Reptiles spread widely, modern insects evolved. A new terrestrial flora developed, including conifers. Several marine species have disappeared.

5. Mesozoic era (225 million - 70 million years ago) with such periods:

Triassic (from the tripartite division of the period proposed in Germany)(225 million - 185 million years ago);

With the advent of the Mesozoic era, Pangea began to disintegrate. On land, the dominance of conifers was established. Diversity among reptiles is noted, the first dinosaurs and giant marine reptiles appeared. Primitive mammals evolved.

Jurassic period(from mountains in Europe)(185 million - 140 million years ago);

Significant volcanic activity was associated with the formation of the Atlantic Ocean. Dinosaurs dominated the land, flying reptiles and primitive birds conquered the air ocean. There are traces of the first flowering plants.

Cretaceous period (from the word "chalk")(140 million - 70 million years ago);

During the maximum expansion of the seas, chalk deposits occurred, especially in Britain. The dominance of dinosaurs continued until the extinction of them and other species at the end of the period.

6. Cenozoic era (70 million years ago - up to our time) with such periods And epochs:

Paleogene period (70 million - 25 million years ago);

— Paleocene epoch ("the oldest part of the new epoch")(70 million - 54 million years ago);
— Eocene epoch ("dawn of a new era")(54 million - 38 million years ago);
— Oligocene era ("not very new")(38 million - 25 million years ago);

Neogene period (25 million - 1 million years ago);

— Miocene epoch ("comparatively new")(25 million - 8 million years ago);
— Pliocene epoch ("very new")(8 million - 1 million years ago);

The Paleocene and Neocene periods are still combined into the Tertiary period. With the advent of the Cenozoic era (new life), there is an abrupt spread of mammals. Many large species have evolved, although many have become extinct. There has been a sharp increase in the number of flowering plants. With the cooling of the climate, herbaceous plants appeared. There has been a significant uplift.

Quaternary period (1 million - our time);

— Pleistocene era ("newest")(1 million - 20 thousand years ago);

— Holocene epoch(“a completely new era”) (20 thousand years ago - our time).

This is the last geological period that includes the present. Four major glaciations alternated with warming periods. The number of mammals has increased; they have adapted to. There was a formation of man - the future ruler of the Earth.

There are also other ways of dividing eras, epochs, periods, eons are added to them, and some epochs are still divided, like in this table, for example.

But this table is more complicated, the confusing dating of some eras is purely chronological, not based on stratigraphy. Stratigraphy is the science of determining the relative geologic age of sedimentary rocks, subdividing rock strata, and correlating different geological formations.

Such a division, of course, is relative, since there was no sharp distinction between today and tomorrow in these divisions.

But still, at the turn of neighboring eras and periods, significant geological transformations mainly took place: the processes of formation of mountains, the redistribution of seas, changing of the climate etc.

Each subsection was characterized, of course, by the originality of flora and fauna.

, And can be found in the same section.

Thus, these are the main eras of the Earth, on which all scientists rely 🙂

The history of our planet still holds many mysteries. Scientists from various fields of natural science have contributed to the study of the development of life on Earth.

It is believed that the age of our planet is about 4.54 billion years. This entire time period is usually divided into two main stages: Phanerozoic and Precambrian. These stages are called eons or eonoteme. Eons, in turn, are divided into several periods, each of which is distinguished by a set of changes that have taken place in the geological, biological, atmospheric state of the planet.

1. Precambrian, or Cryptozoic- this is an eon (time interval of the development of the Earth), covering about 3.8 billion years. That is, the Precambrian is the development of the planet from the moment of formation, the formation of the earth's crust, the proto-ocean and the emergence of life on Earth. By the end of the Precambrian, highly organized organisms with a developed skeleton were already widespread on the planet.

The eon includes two more eonotemes - katarche and archaea. The latter, in turn, includes 4 eras.

1. Katarchaeus- this is the time of the formation of the Earth, but there was still neither the core nor the earth's crust. The planet was still a cold cosmic body. Scientists suggest that during this period there was already water on Earth. The Catarchean lasted about 600 million years.

2. Archaea covers a period of 1.5 billion years. During this period, there was no oxygen on Earth yet, deposits of sulfur, iron, graphite, and nickel were being formed. The hydrosphere and the atmosphere were a single vapor-gas shell, which enveloped in a dense cloud Earth. Sun rays practically did not penetrate through this veil, therefore darkness reigned on the planet. 2.1 2.1. Eoarchean- this is the first geological era, which lasted about 400 million years. The most important event of the Eoarchean is the formation of the hydrosphere. But there was still little water, the reservoirs existed separately from each other and did not yet merge into the world ocean. At the same time, the earth's crust becomes solid, although asteroids are still bombarding the Earth. At the end of the Eoarchean, the first supercontinent in the history of the planet, Vaalbara, is formed.

2.2 Paleoarchaean- the next era, which also lasted approximately 400 million years. During this period, the core of the Earth is formed, tension increases magnetic field. A day on the planet lasted only 15 hours. But the oxygen content in the atmosphere increases due to the activity of bacteria that have appeared. The remains of these first forms of the Paleoarchean era of life have been found in Western Australia.

2.3 Mesoarchean also lasted about 400 million years. In the Mesoarchean era, our planet was covered by a shallow ocean. Land areas were small volcanic islands. But already during this period, the formation of the lithosphere begins and the mechanism of plate tectonics starts. At the end of the Mesoarchean, the first ice age occurs, during which snow and ice form for the first time on Earth. Biological species are still represented by bacteria and microbial life forms.

2.4 Neoarchean- the final era of the Archean eon, the duration of which is about 300 million years. Colonies of bacteria at this time form the first stromatolites (limestone deposits) on Earth. The most important event of the Neoarchean is the formation of oxygen photosynthesis.

II. Proterozoic- one of the longest time periods in the history of the Earth, which is usually divided into three eras. During the Proterozoic, the ozone layer first appears, the world ocean reaches almost its present volume. And after the longest Huron glaciation, the first multicellular life forms appeared on Earth - mushrooms and sponges. The Proterozoic is usually divided into three eras, each of which contained several periods.

3.1 Paleo-Proterozoic- the first era of the Proterozoic, which began 2.5 billion years ago. At this time, the lithosphere is fully formed. But the former forms of life, due to the increase in oxygen content, practically died out. This period is called the oxygen catastrophe. By the end of the era, the first eukaryotes appear on Earth.

3.2 Mesoproterozoic lasted approximately 600 million years. The most important events of this era: the formation of continental masses, the formation of the supercontinent Rodinia and the evolution of sexual reproduction.

3.3 Neo-proterozoic. During this era, Rodinia breaks up into about 8 parts, the super-ocean of Mirovia ceases to exist, and at the end of the era, the Earth is covered with ice almost to the equator. In the Neoproterozoic era, living organisms for the first time begin to acquire a hard shell, which will later serve as the basis of the skeleton.

III. Paleozoic- the first era of the Phanerozoic eon, which began approximately 541 million years ago and lasted about 289 million years. This is the era of the emergence of ancient life. The supercontinent Gondwana unites southern continents, a little later the rest of the land joins it and Pangea appears. Climatic zones begin to form, and flora and fauna are represented mainly by marine species. Only towards the end of the Paleozoic does the development of land begin, and the first vertebrates appear.

The Paleozoic era is conditionally divided into 6 periods.

1. Cambrian period lasted 56 million years. During this period, the main rocks are formed, the mineral skeleton appears in living organisms. And the most important event of the Cambrian is the appearance of the first arthropods.

2. Ordovician period- the second period of the Paleozoic, which lasted 42 million years. This is the era of the formation of sedimentary rocks, phosphorites and oil shale. The organic world of the Ordovician is represented by marine invertebrates and blue-green algae.

3. Silurian period covers the next 24 million years. At this time, almost 60% of living organisms that existed before die out. But the first cartilaginous and bone fish in the history of the planet appear. On land, the Silurian is marked by the appearance of vascular plants. Supercontinents converge and form Laurasia. By the end of the period, ice melting was noted, the sea level rose, and the climate became milder.

4 Devonian is characterized by the rapid development of various forms of life and the development of new ecological niches. Devon covers a time interval of 60 million years. The first terrestrial vertebrates, spiders, and insects appear. Land animals develop lungs. Although fish still dominate. The kingdom of flora of this period is represented by ferns, horsetails, club mosses and gosperms.

5. Carboniferous period often referred to as carbon. At this time, Laurasia collides with Gondwana and the new supercontinent Pangea appears. A new ocean is also formed - Tethys. This is the time when the first amphibians and reptiles appeared.

6. Permian period- the last period of the Paleozoic, which ended 252 million years ago. It is believed that at this time a large asteroid fell to Earth, which led to significant climate change and the extinction of almost 90% of all living organisms. Most of the land is covered with sand, the most extensive deserts appear that have only existed in the entire history of the Earth's development.

IV. Mesozoic- the second era of the Phanerozoic eon, which lasted almost 186 million years. At this time, the continents acquire almost modern outlines. A warm climate contributes to the rapid development of life on Earth. Giant ferns disappear, and angiosperms appear to replace them. The Mesozoic is the era of dinosaurs and the appearance of the first mammals.

The Mesozoic era is divided into three periods: Triassic, Jurassic and Cretaceous.

1. Triassic period lasted a little over 50 million years. At this time, Pangea begins to split, and the inland seas gradually become smaller and dry up. The climate is mild, the zones are not pronounced. Nearly half of land plants are disappearing as deserts spread. And in the realm of fauna, the first warm-blooded and terrestrial reptiles appear, which became the ancestors of dinosaurs and birds.

2 Jurassic covers a gap of 56 million years. A humid and warm climate reigned on Earth. The land is covered with thickets of ferns, pines, palms, cypresses. Dinosaurs reign on the planet, and numerous mammals have so far been distinguished by their small stature and thick hair.

3 Cretaceous- the longest period of the Mesozoic, lasting almost 79 million years. The split of the continents is practically coming to an end, the Atlantic Ocean is significantly increasing in volume, and ice sheets are forming at the poles. Increase water mass oceans leads to the formation greenhouse effect. At the end of the Cretaceous, a catastrophe occurs, the causes of which are still not clear. As a result, all dinosaurs and most species of reptiles and gymnosperms became extinct.

V. Cenozoic- this is the era of animals and Homo sapiens, which began 66 million years ago. The continents at that time acquired their modern shape, Antarctica occupied South Pole Earth, and the oceans continued to grow. Plants and animals that survived the catastrophe of the Cretaceous period found themselves in a completely new world. Unique communities of lifeforms began to form on each continent.

The Cenozoic era is divided into three periods: Paleogene, Neogene and Quaternary.

1. Paleogene period ended approximately 23 million years ago. At that time, a tropical climate reigned on Earth, Europe was hiding under evergreen tropical forests, and deciduous trees grew only in the north of the continents. It was during the Paleogene period that the rapid development of mammals takes place.

2. Neogene period covers the next 20 million years of the planet's development. Whales and bats appear. And, although saber-toothed tigers and mastodons still roam the earth, the fauna is increasingly acquiring modern features.

3. Quaternary period began more than 2.5 million years ago and continues to this day. Two major events characterize this time period: the ice age and the appearance of man. ice age completely completed the formation of the climate, flora and fauna of the continents. And the appearance of man marked the beginning of civilization.

The main stages of the evolution of flora and fauna

Geochronological history of the Earth. It is customary to divide the history of the Earth into periods of time, the boundaries of which are major geological events: mountain-building processes, the rise and fall of land, changes in the outlines of continents, and the level of the oceans. The movements and fractures of the earth's crust that occurred in different geological periods were accompanied by increased volcanic activity, as a result of which a huge amount of gases and ash were released into the atmosphere, which reduced the transparency of the atmosphere and contributed to a decrease in the amount of solar radiation. This was one of the reasons for the development of glaciations, which caused climate change, which had a strong influence on the development of the organic world. In the process of evolution, new forms of organisms, and the former forms, which turned out to be unadapted to the new conditions of existence, died out.

For many millions of years, the remains of once living organisms accumulated on the planet. Based on the finds of fossil forms in the deposits of earth layers, it is possible to trace true story wildlife (Table 4.2). The use of the radioisotope method makes it possible to determine with great accuracy the age of rocks in the places of occurrence of paleontological remains and the age of fossil organisms.

Based on paleontological data, the entire history of life on Earth is divided into eras and periods.

The main stages of plant evolution. In the Proterozoic era (about 1 billion years ago), the trunk of the most ancient eukaryotes was divided into several branches, from which plants, fungi and animals arose. Most of the plants of this period floated freely in the water, some of them attached to the bottom.

Tab. 4.2. Geochronological scale of the Earth.

1. Archean era- the oldest stage in the history of the Earth, when life arose in the waters of the primary seas, which was originally presented precellular its forms and the first cellular organisms. Wasp analysis of this age shows that bacteria and blue-greens lived in the aquatic environment.

2 . Proterozoic era. On the verge of the Archean and Proterozoic eras, the structure and function of organisms became more complex: multicellularity arose, a sexual process that increased the genetic heterogeneity of organisms and provided extensive material for selection; photosynthetic plants became more diverse. The multicellularity of organisms was accompanied by an increase in the specialization of cells, their association into tissues and functional systems.

It is quite difficult to trace in detail the evolution of animals and plants in the Proterozoic era due to the recrystallization of sedimentary rocks and the destruction of organic remains. In the sediments of this era, only imprints of bacteria, algae, lower types of invertebrates and lower chordates. A major step in evolution was the emergence of organisms with bilateral symmetry of the body, differentiated into the anterior and posterior sections, left and right sides, and the isolation of the dorsal and ventral surfaces. The dorsal surface of the animals served as protection, and the mouth and food capture organs were located on the abdominal surface.

3. Paleozoic era. The animal and plant world has reached a great diversity, terrestrial life began to develop.

There are six periods in the Paleozoic: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian. In the Cambrian period, life was concentrated in water (it covered a significant part of our planet) and was represented by more advanced multicellular algae, having a dissected thallus, thanks to which they more actively synthesized organic matter and were the original branch for terrestrial leafy plants. Invertebrates are widespread in the seas, including brachiopods, and from arthropods - trilobites. An independent type of two-layer animals of that period were archaeocyates, which formed reefs in ancient seas. They died out without leaving any descendants. Only lived on land bacteria And mushrooms.

In the Ordovician period, the climate was warm even in the Arctic. In fresh and brackish waters of this period, planktonic seaweed, various corals from the type of coelenterates, there were representatives of almost all types invertebrates including trilobites, mollusks, echinoderms. Bacteria were widely represented. The first representatives of jawless vertebrates appear - shield.

At the end of the Silurian period, in connection with mountain-building processes and a reduction in the area of ​​the seas, part of the algae found themselves in new environmental conditions - in shallow water bodies and on land. Many of them died. However, as a result of multidirectional variability and selection, individual representatives acquired traits that contributed to survival in new conditions. The first terrestrial spore plants appeared - psilophytes. They had a cylindrical stem about 25 cm high, instead of leaves - scales. Their most important adaptations are the appearance of integumentary and mechanical tissues, root-like outgrowths - rhizoids, as well as the elementary conducting system.

In the Devonian, the number of psilophytes declined sharply, they were replaced by their transformed descendants, higher plants - lycopsid, mossy And ferns, which develop real vegetative organs (root, stem, leaf). The emergence of vegetative organs increased the efficiency of the function of individual parts of plants and their vitality as a harmoniously integrated system. The emergence of plants on land preceded the emergence of animals. On Earth, plants accumulated biomass, and in the atmosphere - a supply of oxygen. The first inhabitants of land from invertebrates were spiders, scorpions, centipedes. There were many fish in the Devonian seas, among them - jawed armored, having an internal cartilaginous skeleton and an external strong shell, movable jaws, paired fins. Freshwater bodies inhabited lobe-finned fish that had gill and primitive pulmonary respiration. With the help of fleshy fins, they moved along the bottom of the reservoir, and when they dried up, crawled into other reservoirs. A group of lobe-finned fish was the ancestors of ancient amphibians - stegocephalians. Stegocephals lived in swampy areas, went out onto land, but bred only in water.

In the Carboniferous period, giant ferns spread, which, in a warm, humid climate, settled everywhere. During this period they flourished ancient amphibians.

During the Permian period, the climate became drier and colder, which led to the extinction of many amphibians. By the end of the period, the number of amphibian species began to decline sharply, and only small amphibians (newts, frogs, toads) have survived to this day. Tree-like spore-like ferns have been replaced by seed ferns, giving rise to gymnosperms. The latter had a developed tap root system and seeds, and their fertilization took place in the absence of water. Extinct amphibians were replaced by a more progressive group of animals descended from stegocephals - reptiles. They had dry skin, denser cellular lungs, internal fertilization, egg nutrient storage, protective egg shells.

4. Mesozoic era includes three periods: Triassic, Jurassic, Cretaceous.

Widespread in the Triassic gymnosperms, especially conifers, which have taken a dominant position. At the same time, they spread widely reptiles: ichthyosaurs lived in the seas, plesiosaurs in the air - flying pangolins, reptiles were also diversely represented on earth. Giant reptiles (brontosaurs, diplodocus, etc.) soon became extinct. At the very beginning of the Triassic, a group of small animals with a more perfect structure of the skeleton and teeth separated from the reptiles. These animals acquired the ability to live birth, a constant body temperature, they had a four-chambered heart and a number of other progressive features of organization. These were the first primitive mammals.
in sediments jurassic Mesozoic o6, the remains of the first bird were also discovered - Archeopteryx. It combined in its structure the signs of birds and reptiles.

In the Cretaceous period of the Mesozoic, a branch of plants separated from gymnosperms, which had an organ of seed reproduction - a flower. After fertilization, the ovary of the flower turns into a fruit, so the developing seeds inside the fruit are protected by pulp and shells from adverse environmental conditions. The variety of flowers of various adaptations for pollination and distribution of fruits and seeds made it possible angiosperms (flowering) plants to spread widely in nature and take a dominant position. In parallel with them, a group of arthropods developed - insects which, being pollinators of flowering plants, contributed greatly to their progressive evolution. In the same period appeared real birds And placental mammals. Signs of a high degree of organization in them - a constant body temperature | complete separation of arterial and venous blood flow, increased metabolism, perfect thermoregulation, and in mammals, in addition, live birth, feeding of young with milk, development of the cerebral cortex - allowed these groups to also occupy a dominant position on Earth.

5. Cenozoic era It is divided into three periods: Paleogene, Neogene and Quaternary.

In the Paleogene, Neogene and the beginning of the Quaternary period, flowering plants, thanks to the acquisition of numerous private adaptations, occupied most of the land and represented the subtropical and tropical flora. Due to the cooling caused by the advance of the glacier, the subtropical flora retreated to the south. In the composition of the terrestrial vegetation of temperate latitudes, deciduous trees, adapted to the seasonal rhythm of temperatures, as well as shrubs and herbaceous plants. The flowering of herbaceous plants falls on the Quaternary period. Warm-blooded animals are widely distributed:
birds and mammals. Cave bears, lions, mammoths, woolly rhinoceroses lived during the ice age, which gradually died out after the retreat of the glaciers and the warming of the climate, and the animal world acquired a modern look.

The main event of this era is the formation of man. By the end of the Neogene, small tailed mammals lived in the forests - lemurs And tarsiers. From them came the ancient forms of monkeys - parapithecus, who led an arboreal lifestyle and fed on plants and insects. Their distant descendants are now living gibbons, orangutans and extinct small tree monkeys - dryopithecus. Dryopithecus gave rise to three lines of development that led to chimpanzee, gorilla, as well as extinct Australopithecus. Descended from Australopithecus at the end of the Neogene reasonable person.

The main features of the evolution of the animal world are as follows:

1. progressive development of multicellularity and, as a result, specialization of tissues and all organ systems;
2. a free way of life, which determined the development of various behavioral mechanisms, as well as the relative independence of ontogeny from fluctuations in environmental factors;
3. the appearance of a solid skeleton: external in some invertebrates (arthropods) and internal in chordates;
4. progressive development nervous system, which became the basis for the emergence of conditioned reflex activity

The history of the planet Earth already has about 7 billion years. During this time, our common home has undergone significant changes, which was the result of changing periods. in chronological order reveal the entire history of the planet from its very appearance to the present day.

Geological chronology

The history of the Earth, presented in the form of eons, groups, periods and epochs, is a certain grouped chronology. At the first international congresses of geology, a special chronological scale was developed, which represented the periodization of the Earth. Subsequently, this scale was replenished new information and changed, as a result, now it reflects all geological periods in chronological order.

The largest subdivisions in this scale are eonotemes, eras and periods.

Formation of the Earth

The geological periods of the Earth in chronological order begin their history precisely with the formation of the planet. Scientists have come to the conclusion that the Earth was formed about 4.5 billion years ago. The very process of its formation was very long and, possibly, began as early as 7 billion years ago from small cosmic particles. Over time, the gravitational force grew, along with it, the speed of bodies falling on the forming planet increased. Kinetic energy was transformed into heat, resulting in a gradual heating of the Earth.

The core of the Earth, according to scientists, was formed over several hundred million years, after which the gradual cooling of the planet began. Currently, the molten core contains 30% of the mass of the Earth. The development of other shells of the planet, according to scientists, has not yet been completed.

Precambrian eon

In the geochronology of the Earth, the first eon is called the Precambrian. It covers the time 4.5 billion - 600 million years ago. That is, the lion's share of the history of the planet is covered by the first. However, this eon is divided into three more - Katarchean, Archean, Proterozoic. And often the first of them stands out in an independent eon.

At this time, the formation of land and water occurred. All this happened during active volcanic activity for almost the entire eon. Shields of all continents were formed in the Precambrian, but traces of life are very rare.

Catharhean eon

The beginning of the history of the Earth - half a billion years of its existence in science is called katarchey. The upper limit of this eon is at around 4 billion years ago.

Popular literature portrays the Catarchean as a time of active volcanic and geothermal changes on the Earth's surface. However, this is not actually true.

The Katharhean eon is a time when volcanic activity was not manifested, and the surface of the Earth was a cold, inhospitable desert. Although quite often there were earthquakes that smoothed the landscape. The surface looked like a dark gray primary substance covered with a layer of regolith. The day at that time was only 6 hours.

archean eon

The second main eon out of four in the history of the Earth lasted about 1.5 billion years - 4-2.5 billion years ago. Then the Earth did not yet have an atmosphere, and therefore there was no life yet, but in this eon bacteria appear, due to the lack of oxygen they were anaerobic. As a result of their activities, today we have deposits of natural resources such as iron, graphite, sulfur and nickel. The history of the term "archaea" dates back to 1872, when it was proposed by the famous American scientist J. Dan. The Archean eon, unlike the previous one, is characterized by high volcanic activity and erosion.

Proterozoic eon

If we consider the geological periods in chronological order, the next billion years took the Proterozoic. This period is also characterized by high volcanic activity and sedimentation, and erosion continues over vast areas.

The formation of the so-called. mountains Currently they are small hills on the plains. Rocks of this aeon are very rich in mica, non-ferrous metal ores and iron.

It should be noted that the first living creatures appeared in the Proterozoic period - the simplest microorganisms, algae and fungi. And by the end of the eon, worms, marine invertebrates, and mollusks appear.

Phanerozoic eon

All geological periods in chronological order can be divided into two types - explicit and hidden. Phanerozoic refers to explicit. At this time it appears a large number of living organisms with mineral skeletons. The era preceding the Phanerozoic was called hidden because its traces were practically not found due to the absence of mineral skeletons.

The last about 600 million years of the history of our planet are called the Phanerozoic eon. The most significant events of this eon are the Cambrian explosion, which occurred approximately 540 million years ago, and the five largest extinctions in the history of the planet.

Eras of the Precambrian eon

During the Katarchean and Archean, there were no generally recognized eras and periods, so we will skip their consideration.

The Proterozoic consists of three major eras:

Paleoproterozoic- i.e. ancient, including siderium, riasian period, orosirium and staterium. By the end of this era, the concentration of oxygen in the atmosphere reached its present level.

Mesoproterozoic- average. It consists of three periods - potassium, ectasia and stenia. In this era, algae and bacteria reached their greatest prosperity.

Neoproterozoic- new, consisting of tonium, cryogenium and ediacarium. At this time, the formation of the first supercontinent, Rodinia, takes place, but then the plates parted again. The coldest ice age took place during an era called the Mesoproterozoic, during which most of the planet froze over.

Eras of the Phanerozoic eon

This eon consists of three large epochs, which differ sharply from each other:

Paleozoic, or an era of ancient life. It began about 600 million years ago and ended 230 million years ago. The Paleozoic consists of 7 periods:

1. Cambrian (a temperate climate is formed on Earth, the landscape is low-lying, during this period all modern types of animals originate).
2. Ordovician (the climate on the entire planet is quite warm, even in Antarctica, while the land sinks significantly. The first fish appear).
3. Silurian period (the formation of large inland seas takes place, while the lowlands become increasingly arid due to land uplift. The development of fish continues. The Silurian period is marked by the appearance of the first insects).
4. Devon (appearance of the first amphibians and forests).
5. Lower Carboniferous (dominance of ferns, distribution of sharks).
6. Upper and Middle Carboniferous (appearance of the first reptiles).
7. Perm (most of the ancient animals are dying out).

mesozoic, or the time of the reptiles. Geological history consists of three periods:

1. Triassic (seed ferns die out, gymnosperms dominate, the first dinosaurs and mammals appear).
2. Jura (part of Europe and the western part of America is covered with shallow seas, the appearance of the first toothed birds).
3. Chalk (appearance of maple and oak forests, highest development and the extinction of dinosaurs and toothed birds).

cenozoic, or the time of mammals. Consists of two periods:

1. Tertiary. At the beginning of the period, predators and ungulates reach their dawn, the climate is warm. There is a maximum spread of forests, the oldest mammals are dying out. Approximately 25 million years ago, a person appears and in the Pliocene era, a person arises.
2. Quaternary. Pleistocene - large mammals die out, human society is born, 4 ice ages occur, many plant species die out. Modern era- the last ice age ends, the climate gradually acquires its present form. The supremacy of man on the whole planet.

The geological history of our planet has a long and contradictory development. In this process, there were several extinctions of living organisms, repeated ice ages, periods of high volcanic activity were observed, there were eras of the dominance of various organisms: from bacteria to humans. The history of the Earth began about 7 billion years ago, it was formed about 4.5 billion years ago, and less than a million years ago, man ceased to have competitors in all living nature.