The birth of life on Earth occurred about 3.8 billion years ago, when the formation of the earth's crust ended. Scientists found out that the first living organisms appeared in the aquatic environment, and only a billion years have extended to the surface of the sushi of the first creatures.

The formation of terrestrial flora contributed to the formation of organs and tissues in plants, the ability to multiply by disputes. Animals also evolved significantly and adapted to life on land: there was an internal fertilization, the ability to lay eggs, pulmonary breathing. An important stage of development was the formation of a brain, conditional and unconditional reflexes, survival instincts. The further evolution of animals gave the basis for the formation of humanity.

The division of the history of the Earth on the era and periods gives an idea of \u200b\u200bthe features of the development of life on the planet in different time intervals. Scientists allocate particularly significant events in the formation of life on Earth into separate segments of time - era, which are divided by periods.

There are five er:

• Archean;
• proterozoic;
• paleozoic;
• mesozoic;
• cenozoic.

The Archean Era began about 4.6 billion years ago, when the planet earth only began to form and there were no signs of living on it. Air contained chlorine, ammonia, hydrogen, the temperature reached 80 °, the level of radiation exceeded the permissible boundaries, under such conditions the birth of life was impossible.

It is believed that about 4 billion years ago, our planet collided with the heavenly body, and the result was the formation of the Earth's satellite - the Moon. This event has become significant in the development of life, stabilized the axis of rotation of the planet, contributed to the purification of water structures. As a result, first life originated at the depths of the oceans and the seas: the simplest, bacteria and cyanobacteria.

Proterozoic era lasted about 2.5 billion years to 540 million years ago. Detected residues of single-cell algae, mollusks, ringed worms. Begins to form the soil.

The air at the beginning of the era has not yet been saturated with oxygen, but in the process of the life of the bacteria, the inhabable seas, they began to more and more allocate O 2 into the atmosphere. When the amount of oxygen was at a stable level, many creatures took a step in evolution and switched to aerobic breathing.

Paleozoic era includes six periods.

Cambrian period (530 - 490 million years ago) is characterized by the emergence of representatives of all types of plants and animals. Oceans inhabited algae, arthropods, mollusks, the first chord (Haikoichtis) appeared. Susha remained unnecessary. The temperature was maintained high.

Ordalic period (490 - 442 million years ago). The first settlements of lichens appeared on land, and Megal Proppte (representative of arthropod) began to go ashore to postpone the caviar. The ocean continues to develop vertebrates, coral, sponges.

Silurian (442 - 418 million years ago). Plants come to the land, the figurative fabric is formed in arthropods. The formation of the bone skeleton from vertebrates is completed, sensory authorities appear. There is a population, different climatic zones are formed.

Devonian (418 - 353 million years ago). Characteristic the formation of the first forests, mainly fern. Bone and cartilage appear in the reservoirs, amphibians began to go to the land, new organisms are formed - insects.

Coal period (353 - 290 million years ago). The appearance of amphibians, the launch of the continents occurs, at the end of the period there was a significant cooling, which led to the extinction of many species.

Perm period (290 - 248 million years ago). The land inhabit the reptiles, therapists appeared - mammalian ancestors. The hot climate led to the formation of deserts, where only persistent ferns and some conifers were able to survive.

The Mesozoic Era is divided into 3 periods:

Triassic (248 - 200 million years ago). The development of gone plants, the appearance of the first mammals. Split sushi to continents.

Jurassic period (200 - 140 million years ago). The occurrence of coated plants. The appearance of bird ancestors.

Cretaceous period (140 - 65 million years ago). Covenate (flowering) became the dominant group of plants. Development of higher mammals, real birds.

The Cenozoic Era consists of three periods:

LOWINTERIC PERIOD or Paleogen (65 - 24 million years ago). The disappearance of the majority of challenges, lemurs and primates, later parapite and driming appear, appear. The development of the ancestors of modern mammals - rhinos, pigs, rabbits, etc.

Upperretical period or neogen (24 - 2.6 million years ago). Mammals inhabit sushi, water expanses, air. The appearance of Australopitets is the first ancestors of people. During this period, Alps, Himalayas, Andes were formed.

Quaternary period or anthropogen (2.6 million years ago - our days). The significant event of the period is the emergence of a person, first Neanderthal, and soon Homo Sapiens. The vegetable and animal world gained modern features.

The history of the planet Earth already has about 7 billion years. During this time, our common house has undergone significant changes, which was a consequence of changes in periods. In chronological order, disclose the entire history of the planet from its very appearance to this day.

Geological chronology

The history of the Earth represented in the form of Eonov, 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 with new information and changed, as a result, it now reflects all geological periods in chronological order.

The largest units in this scale are eonotems, era and periods.

Formation of land

Geological periods of land in chronological order are beginning their story precisely from the formation of the planet. Scientists concluded that the Earth was formed about 4.5 billion years ago. The process of its formation itself was very long and, possibly, another 7 billion years ago from small cosmic particles. Over time, the strength of grave grew, together with it the velocity of bodies that have fallen on the forming planet increased. Kinetic energy was transformed into heat, as a result of which the gradual heating of the Earth took place.

The core of the Earth, by the assumptions of scientists, was formed for several hundred million years, after which the gradual cooling of the planet began. Currently, the molten kernel contains 30% of the mass of the Earth. The development of other shells of the planet, according to scientists, is not completed so far.

Precambrian Eon.

In the geochronology of the Earth, the first Eon is called Precambria. It covers time 4.5 billion - 600 million years ago. That is, the lion's share of the history of the planet is covered first. However, this Eon is divided into three - Qatarhai, Archey, Proteroza. Moreover, the first one of them stands out to an independent Eon.

At this time, the formation of sushi and water occurred. All this happened during the active volcanic activity throughout almost all Eon. The shields of all continents were formed in the Precambrian, but traces of life are very rare.

Qatarhai Eon.

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

Popular literature draws us Qatarhai as the time of active volcanic and geothermal changes on the surface of the Earth. However, it really is not true.

Qatarhaei Eon is the time when volcanic activity has not been manifested, and the surface of the Earth was a cold indiscriminate desert. Although the earthquakes often took place, which smoothed the landscape. The surface looked like a dark gray primary substance coated with a layer of regolith. A day at the time was only 6 hours.

Archean Eon.

The second main Eon of four in the history of the Earth continued about 1.5 billion years - 4-2.5 billion years ago. Then the earth had not yet had an atmosphere, therefore there was no lives yet, but the appearance of bacteria, due to the absence of oxygen, they were anaerobic. As a result of their activities today we have deposits of natural fossils, such as iron, graphite, sulfur and nickel. The history of the term "Archei" originates in 1872, then he was offered the famous American scientist J. Dan. The Archean Eon, in contrast to the previous one, is characterized by high volcanic activity and erosion.

Proterozoic Eon.

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

The formation of T. N. The mountains are currently they are small hills on the plains. Mountain breeds of this Eon are very rich in mica, non-ferrous metals and iron ores.

It should be noted that the first living beings appeared in the Proterozoic period - the simplest microorganisms, algae and mushrooms. And by the end of Eon, worms appear, sea invertebrates, mollusks.

Puerozoic Eon.

All geological periods in chronological order can be divided into two types - explicit and hidden. Puerozoa refers to the obvious. At this time, a large number of living organisms with mineral skeletons appear. The epoch preceding the plywood, was named hidden because it was practically not found due to the lack of mineral skeletons.

The last about 600 million years of the history of our planet is called Puerozoic Eon. The most significant events of this Eon - the Cambrian explosion that occurred about 540 million years ago and the five largest extinction in the history of the planet.

Era of Precambrian Eon.

During Qatararya and Archeye did not exist generally accepted ER and periods, so we will miss their consideration.

Proterozoa consists of three large ER:

Paleoproterozoa - i.e. an ancient, which includes the Sidery, Riarsian period, ORZIRI, and graders. By the end of this era, the concentration of oxygen in the atmosphere reached a modern level.

Mesoproterozoa - middle. Consists of three periods - Kalimia, Ectazia and Etia. This era of algae and bacteria achieved the greatest heyday.

Neraverterozoa- A new, consisting of Tony, cryogenic and ediacary. At this time, the formation of the first supercontinent is at the birthplace, but then the plates again diverged. The coldest ice age passed to the era called mesoproterosis, during which most of the planet froze.

Era Puerozoic Eon.

This Eon consists of three large epochs, sharply different from each other:

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

1. Cambrian (a temperate climate is formed on Earth, the landscape is lowered, during this period the birth of all modern types of animals occurs).
2. Ordovik (climate over the entire planet is warm enough, even in Antarctica, while drying is significantly immersed. The appearance of the first fish).
3. The Silurian period (the formation of large intensity seas occurs, while the lowlands become all arid due to raising sushi. The development of fish continues. The silhorial period is marked by the appearance of the first insects).
4. Devon (the emergence of first amphibians and forests).
5. Lower carbon (the domination of fern, the spread of sharks).
6. Upper and medium carbon (the appearance of the first reptiles).
7. Perm (most ancient animals die out).

Mesoza or time reptiles. Geological history consists of three periods:

1. TRIAS (dying out seed ferns, prevail gifted, first dinosaurs and mammals appear).
2. Yura (part of Europe and the western part of America is covered with shallow seas, the appearance of the first tooth birds).
3. Mel (the appearance of maple and oak forests, the highest development and extinction of dinosaurs and tooth birds).

Cenozoa, or mammalian time. Consists of two periods:

1. Tertiary. At the beginning of the period, predators and hoofs reach their dawn, the climate is warm. The maximum distribution of forests is occurring, the oldest mammals die off. Approximately 25 million years ago, a person appears in the era of Pliocene.
2. Quaternary. Pleistocene - large mammals die out, human society emerges, there are 4 glacial periods, many species of plants die off. Modern era - the last glacial period ends, gradually the climate acquires the current appearance. The primacy of a person on the entire planet.

The geological history of our planet has a long and controversial development. In this process, there was a place of several extinction of living organisms, the glacial periods were repeated, there were periods of high volcanic activity, there were eras of the departure of different organisms: from bacteria to humans. The history of the Earth began approximately 7 billion years ago, it was formed about 4.5 billion years ago and only less than a million years ago a person stopped having competitors in all the wildlife.

And the universe. For example, Kant's hypothesis - Laplas, O.Yu. Schmidt, George Buffon, Freda Hoyle, etc. But most scientists tend to believe that the Earth is about 5 billion years.

On the events of the geological past in their chronological sequence gives an idea of \u200b\u200ba single international geochronological scale. Its main divisions are the era: the Archean, Proterozoic, Paleozoic, Mesozoic. Cenozoic. The oldest geological time interval (Archey and Proterezhoy) is also called the Precarchbright. It covers a long time - almost 90% of the whole (the absolute age of the planet, according to modern ideas, is accepted equal to 4.7 billion years).

Inside the ER, smaller time segments are distinguished - periods (for example, Paleogenic, uncoole and quaternary in the Cenozoic era).

In the Archean Era (from Greek - initial, ancient) crystalline rocks (granites, gneisses, shale) were formed. In this era, there were powerful global processes. The study of this era allowed geologists to assume the presence of seas and living organisms in them.

The Proterozoic Era (Era of Early Life) is characterized by deposits of rocks in which the remains of living organisms are found. In this era on the surface of the Earth, the most sustainable areas were formed - platforms. Platforms - these ancient cores - became centers of formation.

Paleozoic era (the era of an ancient life) is distinguished by several stages of powerful mining ,. The Scandinavian Mountains, Urals, Tien Shan, Altai, Apalachi appeared in this era. At this time, animal organisms with a solid skeleton appeared. For the first time, vertebrates appeared: fish, amphibians, reptiles. On average, Paleozoic appeared ground vegetation. Tree ferns, plane and others. Served as material for the formation of coal deposits.

The Mesozoic Era (Era of Middle Life) is also characterized by intense folding. Mountains were formed in areas adjacent to. Among the animals were predicted with reptiles (dinosaurs, proteroauts, etc.), birds and mammals appeared for the first time. The vegetation consisted of ferns, coniferous, at the end of the era appeared coated plants.

In the Cenozoic Era (era of a new life) there is a modern distribution of continents and oceans, intensive plotting movements occur. Mountain chains are formed on the shores of the Pacific Ocean, in the south of Europe and Asia (, Himalayas, the coastal ridges of Cordiller, etc.). At the beginning of the Cenozoic era, the climate was significantly warmer than modern. However, the increase in land area due to the raising of the mainland led to cooling. Extensive iceclocks appeared in the north and. This led to significant changes in plant and animal world. Many animals have died out. There were plants and animals close to modern. At the end of this era, a man appeared and began to intensively settle 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 the beginning, there was one mainland, which was subsequently split into two, and then there was still a division and as a result, five continents were formed to today.

The last billion years of the history of the Earth is associated with the formation of folded areas. At the same time, several tectonic cycles (epochs) are distinguished in the geological history of the last billion: Baikal (End of Proterezhoy), Caledonian (Early Paleozoa), Hercinsky (late Paleozoa), Mesozoic (Mesozoic), Cenozoic or Alpine cycle (from 100 million years and to of the present).
As a result of all the above processes, the Earth acquired a contemporary structure.

We present to your attention an article about the classical understanding of the development of our planet Earth, written in kind, is understandable and not too long ... .. If anyone of the people of mature age was forgotten - it will be interesting to read, well, for those who are not a little, and even for the abstract .

Initially there was nothing. In the endless outer space, there was only a gigantic cloud of dust and gases. It can be assumed that from time to time through this substance at the huge speed, space ships were swept off with representatives of the universal mind. Humanoids looked bored in the portholes and did not even realize that in several billion years in these places the mind and life will be crushed.

A gas-pepped cloud over time was transformed into a sunny system. And after the shone appeared, the planets appeared. One of them was our native land. It happened 4.5 billion years ago. From those distant times, the age of the blue planet is counted, thanks to which we exist in this world.

The whole story of the earth is divided into two huge stages

• The first stage is characterized by the absence of complex living organisms. There were only unicellular bacteria that settled on our planet approximately 3.5 billion years Back.


• The second stage began approximately 540 million years Back. This is the time when living multicellular organisms settled on the ground. There are also plants here and animals. And the environment of their habitat of steel and the sea, and dry. The second period continues to this day, and his crown is a person.

Such huge temporary stages are called eONAMI. Each Eon is inherent in its own eonotem. The latter is a specific stage of the geological development of the planet, which is radically different from other stages of a lithosphere, hydrosphere, an atmosphere, a biosphere. That is, each eonothem is strictly specific and not similar to others.

In total there are 4 Eon. Each of them, in turn, is divided into the era of the development of the Earth, and they are divided by periods. It can be seen that there is a hard gradation of large time intervals, and the genographic development of the planet is taken as the basis.

Qatarhey

The most ancient Eon is called Qatarhai. He began 4.6 billion years ago, and ended 4 billion years ago. Thus, its duration amounted to 600 million years. Time is very old, so it was not divided into either era or for periods. In the time of Qatarhay there was no earthly crust, nor the nucleus. The planet was a cold cosmic body. The temperature in its depths corresponded to the melting point of the substance. From above, the surface was covered with a regolic, as in our moon time. The relief was practically even due to constant powerful earthquakes. No atmosphere and oxygen, naturally, was not.

Archey

The second Eon is called Archey. It began 4 billion years ago, and ended 2.5 billion years ago. Thus, it lasted 1.5 billion years. It is divided into 4 eras:

• eoarhey


• paleoarhey


• mesoarhey


• neoarhey

Eoarhey (4-3.6 billion years) lasted 400 million years. This is the period of formation of the earth's crust. A huge number of meteorites fell on the planet. This is the so-called late grave bombing. It was at the time that the formation of a hydrosphere began. Water appeared on Earth. In large quantities it could be a comet. But the oceans were still far away. There were separate reservoirs, and the temperature in them reached 90 ° Celsius. The atmosphere was characterized by a high content of carbon dioxide and a small content of nitrogen. Oxygen was absent. At the end of this era of the development of the Earth, the first supercontinent of Vaalbara began to form.

Paleoarhey (3.6-3.2 billion years) lasted 400 million years. This era ended the formation of the solid core of the Earth. A strong magnetic field appeared. His tension was half the current one. Consequently, the surface of the planet has received protection from the solar wind. For this period there are primitive forms of life in the form of bacteria. Their remnants whose age is 3.46 billion years, were discovered in Australia. Accordingly, the oxygen content in the atmosphere caused by the activities of living organisms began to increase. The formation of Vaalbara continued.

Mesoarhey (3.2-2.8 billion years) lasted 400 million years. The most noteworthy was the existence of cyanobacteria. They are capable of photosynthesis and excrete oxygen. The formation of the supercontinent was completed. By the end of the era, he split off. There was also a drop in a huge asteroid. Crater from him still exists in the territory of Greenland.

Neoarhey (2.8-2.5 billion years) lasted 300 million years. This is the time of formation of a real earthly crust - tectogenesis. Bacteria continued to develop. Traces of their life are found in Stromatolites, whose age is estimated at 2.7 billion years. These lime deposits were formed by the huge colonies of bacteria. They were found in Australia and South Africa. The photosynthesis continued to be improved.

With the end of Archeye, the Era of the Earth received their continuation in Proterozoic Eon. This is a period of 2.5 billion years - 540 million years ago. He is the longest of all the planet's eoons.

Proterozoa

Proterezhoy is divided into 3 eras. The first is called paleoproterozoa (2.5-1.6 billion years). She continued 900 million years. This huge time interval is divided into 4 periods:

• sidery (2.5-2.3 billion years)


• riasi (2.3-2.05 billion years)


• oRZIRY (2.05-1.8 billion years)


• graders (1.8-1.6 billion years)

Sidery Notable primarily oxygen catastrophe. It happened 2.4 billion years ago. It is characterized by a fundamental change in the atmosphere of the Earth. It appeared in a huge amount of free oxygen. Prior to this, carbon dioxide, hydrogen sulfide, methane and ammonia dominated in the atmosphere. But as a result of photosynthesis and fuse of volcanic activity at the bottom of the oceans, oxygen flooded the entire atmosphere.

Oxygen photosynthesis is characteristic of cyanobacteria, which were broken on Earth 2.7 billion years ago.

Before that, the archaebacteria was dominated. At photosynthesis, oxygen did not produce. In addition, the oxygen was initially spent on the oxidation of rocks. In large quantities, it accumulated only in biocenoses or bacterial mats.

In the end, the moment occurred when the surface of the planet was oxidized. And cyanobacteria continued to release oxygen. And he began to accumulate in the atmosphere. The process accelerated due to the fact that the oceans also ceased to absorb this gas.

As a result, the anaerobic organisms were killed, and they were replaced by aerobic, that is, those in which the energy synthesis was carried out by free molecular oxygen. The planet enveloped the ozone layer and the greenhouse effect decreased. Accordingly, the boundaries of the biosphere expanded, and the sedimentary and metamorphic rocks turned out to be fully oxidized.

All these metamorphoses led to Guronian glaciationwhich lasted 300 million years. It began in Sidery, but ended at the end of Riacia 2 billion years ago. Next period Oroziriy Notable intensive processing processes. At this time, 2 huge asteroid fell on the planet. Crater from one called Harmfort And located in South Africa. Its diameter comes up to 300 km. Second crater Sudbery Located in Canada. Its diameter is 250 km.

Last stationing period Notable for the formation of the supercontinent of Columbia. It includes almost all the continental blocks of the planet. There was a supercontinent of 1.8-1.5 billion years ago. At the same time, cells were formed that contained the kernels. That is, eukaryota cells. It was a very important stage of evolution.

The second era of the Proterezhoy is called mesoproterozoa (1.6-1 billion years). Its duration amounted to 600 million years. It divides on 3 periods:

• kalimia (1.6-1.4 billion years)


• exath (1.4-1.2 billion years)


• stances (1.2-1 billion years).

In times, such an era of the development of the Earth, like Kalimia, the supercontinent of Columbia broke up. And during the exam, red multicellular algae appeared. This is indicated by the fossil find on the Canadian Island Somerset. Her age is 1.2 billion years. It suffered a new supercontinent of the birth. It was 1.1 billion years ago, and 750 million years ago broke up. Thus, by the end of the mesoprotorerosis on Earth, there was 1 supercontinent and 1 ocean, which called the world.

The last era of the properozoy is called neraverterozoa (1 billion-540 million years). It includes 3 periods:

• tonyi (1 billion-850 million years)


• cryogens (850-635 million years)


• edicary (635-540 million years)

During Tiona, the decay of the supercontinent of the birthplace began. This process ended in cryogenation, and began to form a supercontinent of the pannage from 8 formed individual slices of sushi. For crying, the planet (earth-snow) is also characteristic. Ides reached the equator, and after they retreated, the process of the evolution of multicellular organisms sharply accelerated. The last period of Nerterozoic Edicary is notable for the appearance of soft beings. These multicellular animals got a name vendobiony. They were branching tubular structures. This ecosystem is considered ancient.

Life on Earth originated in the ocean

Puerozoa

Approximately 540 million years ago, the time of the 4th and last Eon - Puerozoos began. Here are 3 very important era of the earth. The first is called paleozoic (540-252 million years). She lasted 288 million years. Divided by 6 periods:

• cambriy (540-480 million years)


• ordovik (485-443 million years)


• silico (443-419 million years)


• devon (419-350 million years)


• carbon (359-299 million years)


• perm (299-252 million years)

Cambrian It is considered the time of life of trilobites. These are marine animals similar to crustaceans. Encouraged with them in the seas, jellyfish, sponges and worms lived. Such an abundance of living beings is called cambrian explosion. That is, before that, nothing like this was and suddenly appeared sharply. Most likely, mineral skeletons began to be born in Kebria. Previously, the living world had soft bodies. They naturally not survived. Therefore, complex multicellular organisms of more ancient eras are impossible to detect.

Paleozoic is notable for the rapid resettlement of organisms with solid skeletons. Fisms, reptiles and amphibians appeared from the vertebrates. In the floral world, algae prevailed at the beginning. During silora Plants began to master the land. At the beginning devon The swampy shores walked by primitive representatives of the flora. These were psulophitis and pteridity. Multiplied plants with disputes that endured the wind. Plant shoots developed on tuber or quenching rhizomes.

Plants began to master land in the Silia

Scorpions appeared, spiders. The real giant was dragonfly Meganevra. The scope of her wings reached 75 cm. Ancanthuddes are considered ancient bone fish. They lived in the Silia period. Their bodies were covered with dense rhombid scales. IN carbonwhich is also called a coal period, on the shores of Lagun and in countless tops, the most diverse vegetation has grunted. It is its remnants and served as the basis for the formation of coal.

This time is also characterized by the beginning of the education of Supercontinent Pangea. He was completely formed in the Perm period. And 200 million was broke up for 2 continents. This is the northern continent of Laurela and South Continent Gondwan. Subsequently, the laure was split, and Eurasia and North America were formed. South America, Africa, Australia and Antarctica arose from Gondwana.

On the permian There were frequent climate change. Dry times were replaced by wet. At this time, brown vegetation appeared on the shores. Typical plants were Cordates, Calamites, tree and seed ferns. Mesozavra lizards appeared in the water. Their length reached 70 cm. But by the end of the Perm period, early reptiles died out and gave way to more developed spinal. Thus, in Paleozoa, life reliably and tightly settled on the blue planet.

Of particular interest among scientists cause the following era of land development. 252 million years ago came mesoza. He continued 186 million years and ended 66 million years ago. Consisted of 3 months:

• tRIAS (252-201 million years)


• yura (201-145 million years)


• chalk (145-66 million years)

The boundary between the Perm and Triassic period is characterized by mass extinction of animals. 96% of marine species and 70% of terrestrial vertebrates were killed. According to the biosphere, a very strong blow was applied, and she was restored for a very long time. And everything ended with the advent of dinosaurs, pterosaurov and ichthyozavrov. These marine and terrestrial animals were huge sizes.

But the main tectonic event of those years is the decay of panga. A single supercontinent, as already mentioned, was divided into 2 continents, and then collapsed on those continents that we know now. Indian subcontinent will be lost. Subsequently, he joined the Asian slab, but the collision was so harsh that Himalayas arose.

Such nature was in the early chalk

Mesoza is remarkable by the fact that it is considered the warmer period of Puerrozoic Eon. This is the time of global warming. It began in Triassa, and ended at the end of the chalk. 180 million years even in the Polar, there were no sustainable packing glaciers. Warm on the planet spread uniformly. At the equator, the average annual temperature corresponded to 25-30 ° Celsius. Moderately cool climate was characteristic of the supremacy. In the first half of the mesozoy, the climate was dry, and for the second half it is characterized by wet. It was at that time an equatorial climatic belt was formed.

In the animal world, mammals arose from the subclass of repties. It was connected with the improvement of the nervous system and the brain. The limbs moved from the sides under the body, became more perfect in the curriculum. They ensured the development of the embryo in the body of the mother, followed by the false milk. It appeared woolen cover, the blood circulation and metabolism were improved. The first mammals appeared in Triassa, but they could not compete with dinosaurs. Therefore, more than 100 million years old were the dominant position in the ecosystem.

The last era is considered cenozoa (Start 66 million years ago). This is the current geological period. That is, we all live in Cenozoa. It is divided into 3 periods:

• paleogen (66-23 million years)


• neogen (23-2.6 million years)


• modern anthropogen or quaternary period, which began 2.6 million years ago.

2 main events are observed in Cenozoa. Mass extinction of dinosaurs 65 million years ago and the overall cooling on the planet. The death of animals is associated with a fall of a huge asteroid with a high content of iridium. The diameter of the cosmic body reached 10 km. As a result, the crater was formed Chiksulub With a diameter of 180 km. He is on the Yucatan Peninsula in Central America.

Earth surface 65 million years ago

After the fall, an explosion of huge strength occurred. The atmosphere rose dust and closed the planet from the sun's rays. The average temperature fell by 15 °. Dust hung in the air for a whole year, which led to a sharp cooling. And since the land inhabited large thermal-loving animals, they became extinct. Only small representatives of the fauna remained. They were the ancestors of a modern animal world. This theory is based on Iridia. The age of its layer in geological sediments is just 9 million years old.

In the time of Cenozoic, the mainland diverged. Each of them was formed their own unique flora and fauna. The variety of marine, flying and terrestrial animals has increased significantly in comparison with Paleozoa. They became much more perfect, and the dominant position on the planet occupied mammals. In the vegetable world, higher coated plants appeared. This is the presence of a flower and a seedhead. Cold crops also appeared.

The most important in the last era is anthropogen or quaternary period, I started 2.6 million years ago. It consists of 2 epochs: Pleistocene (2.6 million years-11.7 thousand years) and Golocene (11.7 thousand years old, ours). In the era of Pleistocene Mammoths, cave lions and bears, short lions, saber-toothed cats and many other animals, extinct at the end of the era, lived on Earth. 300 thousand years ago a man appeared on the Blue Planet. It is believed that the first Crohanions were chosen for themselves the eastern regions of Africa. At the same time, Neanderthals lived on the Pyrenees Peninsula.

Noteworthy Pleistáze and glacier periods. A lot of 2 million years on Earth alternated very cold and warm periods of time. Over the past 800 thousand years, there are 8 glacial periods with an average duration of 40 thousand years. In cold times, the glaciers fell on the continents, and in the interdnicker retreated. At the same time increased the level of the world's ocean. About 12 thousand years ago, already in Golotocene, ended the next ice age. The climate became warm and wet. Due to this, humanity settled throughout the planet.

Golocene is a password. It continues 12 thousand years old. The last 7 thousand years have developed human civilization. The world has changed in many ways. Significant transformation, thanks to the activity of people, underwent Flora and Fauna. Nowadays, many species of animals are on the verge of destruction. A person has long considered himself the Lord of the world, but the era of the earth did not share anywhere. The time continues its steady move, and the blue planet is conscientious of the sun around the sun. In short, life continues, but what will happen next - will show the future.

Dinosaur bones and amazing extinct animals were found in different epochs of human history. In the absence of science on the found bones folded the legends of giants or dragons. Examine on paleontological finds The main stages of the development of life on Earth were able to only modern people with the development of science.

Earth Education

Our planet formed about 4.5 billion years ago from star dust and solid particles. With increasing gravity, the Earth began to attract debris and stones from space, which fell to the surface, gradually warming up the planet. Over time, the top layer compacted and began to cool. Hot mantle supports heat so far, not giving the earth to turn into a block of ice.

For a long time, the planet was in lifeless condition. The atmosphere was filled with various gases and did not contain oxygen. Thanks to the ejection of a large number of steam from the depths of the earth and the gravity began to form dense clouds. Intensive rains contributed to the emergence of the World Ocean, in which life originated.

Fig. 1. Formation of the Earth.

Oxygen appeared in the atmosphere with the advent of the first photosynthetic plants.

Stages of development

Life on earth is associated with geological eonas and eras. Eon is a large segment of geological history, combining several er. In turn, the era are divided into periods. For each era, the individual development of animal and vegetable world, which often depended on the climate, the state of the earth's crust, underground activity.

Fig. 2. Era of the geological history of the Earth.

A more detailed description of the Eon is presented in the table of the main stages of the development of life on Earth.

Top-1 articlewho read with this

Eon.	Era	Period	Characteristic
Qatarhey			About 4.5 billion years ago began, 4 billion years ago ended. Sedimentary breeds are unknown. The surface of the planet lifeless and crucified by crater
			Lasted from 4 to 2.5 billion years ago. At the end of Eoarhey, the first single-cell organisms appeared - anaerobic bacteria. The formation of carbonate sediments and minerals. Formation of continents. Oxygen is formed in neoarhey due to cyanobacteria
	Paleoarhey
	Mesoarhey
	Neoarhey
Proterozoa	Paleoproterozoa		A period of 2.5 to 1.6 billion years ago. More advanced cyanobacteria distinguish a large amount of oxygen, which leads to an oxygen catastrophe. Oxygen becomes destroyed for anaerobic organisms. In the stationed the first aerobic eukaryotes arise
		Oroziri.
		Stationery
	Mesoproterozoa		Lasted 1.6-1 billion years ago. Sedimentary rocks are formed. In the Etasia, the first multicellular organisms appear - red algae. Eukarotes that breed the sexual way occur
	Neraverterozoa		1 billion years ago began and ended 542 million years ago. Strong glaciation of the earth's crust. The first multicellular mild animals appear in Edicary - Vendobion
		Cryogenies
		Edicary
Puerozoa	Paleozoic		Lasted from 541 to 290 million years ago. At the beginning of the era, a species diversity of living organisms appears. An extinction occurred between the Ordivik and the Silurus, as a result of which more than 60% of living beings disappeared, but in Devon, the life began to master new ecological niches. There were horseships, ferns, gicked plants, a large number of fish cilapies, the first vertebrates terrestrial animals, insects, spiders, ammonites. At the end of Devon also extinction takes place. Reptiles, amphibians, mollusks, msanka, arthropods, cartilage fish appear in the carbon. In the Perm period, beetles arise, net-pot insects, predatory beasts
			252 million began and ended 66 million years ago. At the junction of Perm and Triass, the largest mass extinction occurs, as a result of which 90% of marine inhabitants disappear and 70% of ground. In the Jurassic period there are first flowering plants that displacing gone. Reptiles and insects occupy a dominant position. In the chalk period there is cooling and extinction of most plants. This leads to the death of herbivores, and then predatory reptiles. First birds and mammals come to shift
	Cenozoa	Paleogen	It began 66 million years ago and continues until now. A variety of birds, plants, insects. Whales, marine hedgehogs, ceps, elephants, horses appear. In Anthropogen - the current period - about 2 million years ago, the first people appeared (Homo)