When did the first living organisms appear on Earth? Faith begins where knowledge ends.

Each of us sometimes worries about such questions that are difficult to find answers. These include understanding the meaning of one's existence, the structure of the world, and much more. We believe that everyone once thought about the development of life on Earth. The eras that we know are very different from each other. In this article, we will analyze in detail, and how exactly its evolution took place.

catarchean

Katarchaeus - when the earth was lifeless. There were volcanic eruptions everywhere, ultraviolet radiation and no oxygen. The evolution of life on Earth began its countdown precisely from this period. Due to the interaction of chemicals that have enveloped the earth, properties characteristic of life on Earth begin to form. However, there is another opinion. Some historians believe that the Earth has never been empty. In their opinion, the planet exists as long as life on it.

The katarchean era lasted from 5 to 3 billion years ago. Studies have shown that during this period the planet did not have a core and the earth's crust. An interesting fact is that at that time the day lasted only 6 hours.

archaeus

The next era after the Catarchean is the Archean (3.5-2.6 billion years BC). It is divided into four periods:

• neoarchean;
• mesoarchean;
• paleoarchaean;
• eoarchean.

It was during the Archean that the first simple microorganisms arose. Few people know, but the deposits of sulfur and iron that we mine today appeared during this period. Archaeologists have found the remains of filamentous algae, the age of which allows them to be attributed to the Archean period. At this time, the evolution of life on Earth continued. heterotrophic organisms appear. Soil is formed.

Proterozoic

The Proterozoic is one of the longest periods of the Earth's development. It is divided into the following steps:

• mesoproterozoic;
• neoproterozoic.

This period is characterized by the appearance of the ozone layer. Also, it was at this time, according to historians, that the volume of the world ocean was fully formed. The Paleoproterozoic era included the Siderian period. It was in it that the formation of anaerobic algae occurred.

Scientists note that it was in the Proterozoic that global glaciation occurred. It lasted for 300 million years. A similar situation is characterized by the ice age, which was much later. During the Proterozoic, sponges and fungi appeared among them. It was during this period that deposits of ore and gold were formed. The Neoproterozoic era is characterized by the formation of new continents. Scientists note that all the flora and fauna that existed during this period is not the ancestor of modern animals and plants.

Paleozoic

Scientists have been studying the geological eras of the Earth and the development of the organic world for a long time. In their opinion, the Paleozoic is one of the most significant periods for our modern life. It lasted about 200 million years and is divided into 6 time periods. It was during this era of the development of the Earth that land plants began to form. It is worth noting that during the Paleozoic period, animals came to land.

The Paleozoic era was studied by many famous scientists. Among them are A. Sedgwick and E. D. Phillips. It was they who divided the era into certain periods.

Paleozoic climate

Many scientists have done research to find out the Era, as we said earlier, could last long enough. It is for this reason that during one chronology on a certain part of the Earth at different times there can be an absolutely opposite climate. So it was in the Paleozoic. At the beginning of the era, the climate was milder and warmer. There was no zoning as such. The percentage of oxygen constantly increased. The water temperature was between 20 degrees Celsius. Over time, zonation began to appear. The climate became hotter and more humid.

By the end of the Paleozoic, as a result of the formation of vegetation, active photosynthesis began. A more pronounced zoning appeared. Climatic zones formed. This stage has become one of the most important for the development of life on Earth. The Paleozoic era gave impetus to the enrichment of the planet with flora and fauna.

Flora and fauna of the Paleozoic era

At the beginning of the Paleosian period, life was concentrated in water bodies. In the middle of the era, when the amount of oxygen reached a high level, land development began. Its very first inhabitants were plants, which first performed their vital activity in shallow water, and then moved to the shore. The first representatives of the flora that mastered the land are psilophytes. It is worth noting that they did not have roots. The process of formation of gymnosperms is also referred to the Paleozoic era. Tree-like plants also appeared. In connection with the appearance of flora on earth, animals gradually began to appear. Scientists suggest that herbivorous forms were the first to arise. The process of development of life on Earth lasted for quite a long time. Era and living organisms are constantly changing. The first representatives of the fauna are invertebrates and spiders. Over time, insects with wings, ticks, mollusks, dinosaurs, reptiles appeared. In the late period of the Paleozoic, significant climatic changes occurred. This led to the extinction of some animal species. According to preliminary estimates, about 96% of the inhabitants of the water and 70% of the land died.

Minerals of the Paleozoic era

It is with the Paleozoic period that the formation of many minerals is associated. Rock salt deposits began to form. It is also worth emphasizing that some oil basins originate precisely from the beginning of the formation of coal strata, which account for 30% of the total. Also, the formation of mercury is associated with the Paleozoic period.

Mesozoic

The next after the Paleozoic was the Mesozoic. It lasted about 186 million years. The geological history of the Earth began much earlier. However, it was the Mesozoic that became the era of activity, both climatic and evolutionary. The main boundaries of the continents were formed. Mountain building has begun. There was a division of Eurasia and America. It is believed that it was in the climate that was the warmest. However, at the end of the era, the ice age began, which significantly changed the flora and fauna of the earth. Natural selection has taken place.

Flora and fauna in the Mesozoic era

The Mesozoic era is characterized by the extinction of ferns. Gymnosperms and conifers predominate. Angiosperms are formed. It was in the Mesozoic period that the fauna flourished. The most developed are reptiles. In this period, there were a large number of their subspecies. Flying reptiles appear. Their growth continues. By the end, some representatives weigh about 50 kilograms.

In the Mesozoic, the development of flowering plants gradually begins. By the end of the period, a cold snap sets in. The number of subspecies of near-aquatic plants is decreasing. Gradually, invertebrates also die out. It is for this reason that birds and mammals appear.

According to scientists, birds originated from dinosaurs. They associate the emergence of mammals with one of the subclasses of reptiles.

Cenozoic

Cenozoic is exactly the era in which we live today. It began about 66 million years ago. At the beginning of the era, the division of the continents was still taking place. Each of them was dominated by its own flora, fauna and climate.

Cenozoic is distinguished by a large number of insects, flying and marine animals. Mammals and angiosperms predominate. It was at this time that all living organisms evolve strongly and are distinguished by a large number of subspecies. Grains appear. The most important transformation is the emergence of Homo sapiens.

Human evolution. Initial stages of development

The exact age of the planet cannot be determined. Scientists have been arguing about this topic for a long time. Some believe that the age of the Earth is 6,000 thousand years, others that it is more than 6 million. Guess we'll never know the truth. The most important achievement of the Cenozoic era is the appearance of Homo sapiens. Let's take a closer look at exactly how this happened.

There are a large number of opinions regarding the formation of mankind. Scientists have repeatedly compared a wide variety of sets of DNA. They came to the conclusion that monkeys have the most similar organism to humans. It is impossible to prove this theory to the end. Some scientists argue that the human and pig bodies are also quite similar.

Human evolution is visible to the naked eye. At first, biological factors were important for the population, and today social factors are important. Neanderthal, Cro-Magnon, Australopithecus and others - all of which our ancestors went through.

Parapithecus is the first stage in the development of modern man. At this stage, our ancestors existed - monkeys, namely chimpanzees, gorillas and orangutans.

Australopithecus was the next stage of development. The first found remains were in Africa. According to preliminary data, their age is about 3 million years. Scientists examined the find and came to the conclusion that australopithecines are quite similar to modern humans. The growth of representatives was quite small, about 130 centimeters. The mass of Australopithecus was 25-40 kilograms. The guns, most likely, they did not use, since they were never found.

A skilled man was similar to Australopithecus, but, unlike them, he used a primitive tool. His hands and knuckles were more developed. It is believed that a skilled person is our direct ancestor.

Pithecanthropus

The next stage of evolution was Pithecanthropus - Homo erectus. Its first remains were found on the island of Java. According to scientists, pithecanthropes lived on the Earth about a million years ago. Later, the remains of Homo erectus were found in all corners of the planet. Based on this, we can conclude that Pithecanthropes inhabited all continents. The body of a erect human was not much different from the modern one. However, there were minor differences. Pithecanthropus had a low forehead and well-defined brow ridges. Scientists have found that an upright person led an active lifestyle. Pithecanthropes hunted and made simple tools. They lived in groups. So it was easier for Pithecanthropes to hunt and defend themselves from the enemy. Finds in China allow us to conclude that they also knew how to use fire. Pithecanthropes developed abstract thinking and speech.

Neanderthal

Neanderthals lived about 350 thousand years ago. Found about 100 remains of their life. The Neanderthal skull was domed. Their height was about 170 centimeters. They had a fairly large physique, well-developed muscles and good physical strength. They had to live in the Ice Age. It is thanks to this that Neanderthals learned to sew clothes from leather and constantly keep fire. There is an opinion that Neanderthals lived only on the territory of Eurasia. It is also worth noting that they carefully processed the stone for the future tool. The Neanderthals often used wood. From it they created a tool of labor and elements for dwellings. However, it is worth noting that they were quite primitive.

Cro-Magnon

Cro-Magnons were tall, which was about 180 centimeters. They had all the signs of modern man. Over the past 40 thousand years, their appearance has not changed at all. After analyzing the remains of a person, scientists concluded that the average age of the Cro-Magnons was about 30-50 years. It is worth noting that they created more complex types of weapons. Among them are knives and harpoons. The Cro-Magnons fished, and therefore, in addition to the standard set of weapons, they also created new ones for comfortable fishing. Among them are needles and much more. From this we can conclude that the Cro-Magnons had a well-developed brain and logic.

A reasonable man built his dwelling out of stone or dug it out of the ground. The nomadic population created temporary huts for greater convenience. It is also worth noting that the Cro-Magnons tamed the wolf, turning it over time into a watchdog.

Cro-Magnons and art

Few people know that it was the Cro-Magnons who formed the concept that we now know as the concept of creativity. On the walls of a large number of caves, rock paintings made by the Cro-Magnons were found. It is worth emphasizing that the Cro-Magnons always left their drawings in hard-to-reach places. Perhaps they performed some kind of magical role.

The Cro-Magnon people had a variety of drawing techniques. Some clearly traced the images, while others scratched them. Cro-Magnons used colored paints. Predominantly red, yellow, brown and black. Over time, they even began to carve human figures. You can easily find all the exhibits found in almost any archaeological museum. Scientists note that the Cro-Magnons were quite developed and educated. They liked to wear jewelry made from the bones of the animals they had killed.

There is quite an interesting opinion. Previously, it was believed that the Cro-Magnons ousted the Neanderthals in an unequal struggle. Scientists today think differently. They believe that for a certain amount of time, Neanderthals and Cro-Magnons lived side by side, but the weaker ones died from a sharp cold snap.

Summing up

The geological history of the Earth began many millions of years ago. Each era has contributed to our modern life. We often do not think about how our planet has evolved. Studying the information about how our Earth was formed, it is impossible to stop. The history of the evolution of the planet can bewitch everyone. We strongly recommend that we take care of our Earth, if only so that after millions of years the history of our existence will have someone to study.

Life on Earth originated over 3.5 billion years ago, immediately after the completion of the formation of the earth's crust. Throughout time, the emergence and development of living organisms influenced the formation of relief and climate. Also, tectonic and climatic changes that have taken place over the years have influenced the development of life on Earth.

A table of the development of life on Earth can be compiled based on the chronology of events. The entire history of the Earth can be divided into certain stages. The largest of them are the eras of life. They are divided into eras, eras - into - into eras, eras - into centuries.

Ages of life on earth

The entire period of the existence of life on Earth can be divided into 2 periods: the Precambrian, or Cryptozoic (primary period, 3.6 to 0.6 billion years), and Phanerozoic.

Cryptozoic includes the Archean (ancient life) and Proterozoic (primary life) eras.

Phanerozoic includes the Paleozoic (ancient life), Mesozoic (middle life) and Cenozoic (new life) eras.

These 2 periods of development of life are usually divided into smaller ones - eras. The boundaries between eras are global evolutionary events, extinctions. In turn, eras are divided into periods, periods - into epochs. The history of the development of life on Earth is directly related to changes in the earth's crust and the planet's climate.

Era of development, countdown

It is customary to single out the most significant events in special time intervals - eras. Time is counted backwards, from ancient life to the new. There are 5 eras:

1. Archean.
2. Proterozoic.
3. Paleozoic.
4. Mesozoic.
5. Cenozoic.

Periods of development of life on Earth

The Paleozoic, Mesozoic and Cenozoic eras include periods of development. These are smaller periods of time, compared to eras.

Palaeozoic:

• Cambrian (Cambrian).
• Ordovician.
• Silurian (Silur).
• Devonian (Devonian).
• Carboniferous (carbon).
• Perm (Perm).

Mesozoic era:

• Triassic (Triassic).
• Jura (Jurassic).
• Cretaceous (chalk).

Cenozoic era:

• Lower Tertiary (Paleogene).
• Upper Tertiary (Neogene).
• Quaternary, or anthropogen (human development).

The first 2 periods are included in the Tertiary period lasting 59 million years.

The development of living organisms

The table of the development of life on Earth involves the division not only into time intervals, but also into certain stages of the formation of living organisms, possible climatic changes (ice age, global warming).

• Archean era. The most significant changes in the evolution of living organisms are the appearance of blue-green algae - prokaryotes capable of reproduction and photosynthesis, the emergence of multicellular organisms. The appearance of living protein substances (heterotrophs) capable of absorbing organic substances dissolved in water. In the future, the appearance of these living organisms made it possible to divide the world into flora and fauna.

• Mesozoic era.

• Triassic. Distribution of plants (gymnosperms). An increase in the number of reptiles. The first mammals, bony fish.
• Jurassic period. The predominance of gymnosperms, the emergence of angiosperms. The appearance of the first bird, the flowering of cephalopods.
• Cretaceous period. Spread of angiosperms, reduction of other plant species. The development of bony fish, mammals and birds.

• Cenozoic era.
  • Lower Tertiary period (Paleogene). The flowering of angiosperms. The development of insects and mammals, the appearance of lemurs, later primates.
  • Upper Tertiary period (Neogene). The development of modern plants. The appearance of human ancestors.
  • Quaternary period (anthropogen). Formation of modern plants, animals. The appearance of man.

Development of conditions of inanimate nature, climate change

The table of the development of life on Earth cannot be presented without data on changes in inanimate nature. The emergence and development of life on Earth, new species of plants and animals, all this is accompanied by changes in inanimate nature and climate.

Climate Change: Archean Era

The history of the development of life on Earth began through the stage of the predominance of land over water resources. The relief was poorly outlined. The atmosphere is dominated by carbon dioxide, the amount of oxygen is minimal. Salinity is low in shallow water.

The Archean era is characterized by volcanic eruptions, lightning, black clouds. The rocks are rich in graphite.

Climatic changes during the Proterozoic era

Land is a stone desert, all living organisms live in water. Oxygen accumulates in the atmosphere.

Climate change: the Paleozoic era

During various periods of the Paleozoic era, the following occurred:

• Cambrian period. The land is still deserted. The climate is hot.
• Ordovician period. The most significant changes are the flooding of almost all northern platforms.
• Silurian. Tectonic changes, the conditions of inanimate nature are diverse. Mountain building occurs, the seas prevail over the land. Regions of different climates, including areas of cooling, were determined.
• Devonian. Dry climate prevails, continental. Formation of intermountain depressions.
• Carboniferous period. The sinking of the continents, wetlands. The climate is warm and humid, with a lot of oxygen and carbon dioxide in the atmosphere.
• Permian period. Hot climate, volcanic activity, mountain building, drying up of swamps.

In the Paleozoic era, mountains formed. Such changes in the relief affected the world's oceans - the sea basins were reduced, a significant land area was formed.

The Paleozoic era marked the beginning of almost all major deposits of oil and coal.

Climatic changes in the Mesozoic

The climate of different periods of the Mesozoic is characterized by the following features:

• Triassic. Volcanic activity, the climate is sharply continental, warm.
• Jurassic period. Mild and warm climate. The seas prevail over the land.
• Cretaceous period. Retreat of the seas from the land. The climate is warm, but at the end of the period, global warming is replaced by cooling.

In the Mesozoic era, the previously formed mountain systems are destroyed, the plains go under water (Western Siberia). In the second half of the era, the Cordilleras, the mountains of Eastern Siberia, Indochina, partly Tibet, formed the mountains of the Mesozoic folding. A hot and humid climate prevails, contributing to the formation of swamps and peat bogs.

Climate change - Cenozoic era

In the Cenozoic era, there was a general uplift of the Earth's surface. The climate has changed. Numerous glaciations of the earth covers advancing from the north have changed the appearance of the continents of the Northern Hemisphere. Due to such changes, hilly plains were formed.

• Lower Tertiary period. Mild climate. Division into 3 climatic zones. Formation of continents.
• Upper Tertiary period. Dry climate. The emergence of steppes, savannahs.
• Quaternary period. Multiple glaciation of the northern hemisphere. Climate cooling.

All changes during the development of life on Earth can be written in the form of a table that will reflect the most significant stages in the formation and development of the modern world. Despite the already known methods of research, even now scientists continue to study history, make new discoveries that allow modern society to find out how life developed on Earth before the appearance of man.

Constantly evolving and changing. This process of continuous change is called evolution. Studying it in conjunction with environmental changes, ecologists have learned a lot of interesting things about the development of our planet. They found that the relationship between a living organism and its environment is extremely important for life. The development of the human embryo in the mother's womb is one of the evidences of evolution. For nine months of pregnancy, the fetus goes through a difficult path of development - from a single-celled organism to a person. These changes reflect an evolution spanning billions of years, in which tiny, single-celled organisms evolved into the most complex modern life forms. At some point in development, the human embryo even develops gill slits; they are reminiscent of our most distant relatives in the world of fish.

Fossils are the key to the study of evolution

Fossils are the remains or imprints of ancient plants and animals preserved in rocks. Sometimes the shell or bone turns into minerals and retains its shape. Sometimes in the rocks there are imprints of the bodies of ancient animals that have long disappeared. Paleontology, the science that studies imprints, is one of the main sources of information about the forms of life on Earth in the most ancient era and about their development. Fossils occur in certain dateable rocks, and therefore their age can be determined. By comparing fossils from different eras, it is possible to trace the development of life on Earth. Sometimes there are whole fossilized skeletons of dinosaurs.

collecting fossils

Fossils are usually found in layers of sandstone, limestone or shale, although they can be found in other rocks. When collecting fossils, be extremely careful and observant: they are very difficult to spot. Pay attention to anything unusual, whether it be the shape, color, or type of inclusions in the rocks. To break out pieces of rock, have a hammer and chisel with you. If you're lucky, you might be able to start your own fossil collection.

Darwinism

Scientists have put forward many different theories about how evolution proceeded. In the last 150 years, most scientists believe that the theory of Charles Darwin describes the process of evolution more reliably than others. It is based on the principle of natural selection, or the struggle for existence, which underlies the emergence and development of diverse forms of life. The theory of natural selection claims that those plants and animals survive that better adapt to environmental conditions (see the article ""). Adapting, organisms change their structure somewhat, and these changes are transmitted to the next generation. So organisms gradually change over a long time. For example, due to smog in England in the XIX century. dark-colored moths had an easier time surviving than silver moths. As a result, the number of dark moths increased markedly - more of them were born.

Beyond Darwinism

Some modern scientists believe that certain facts cannot be explained on the basis of Darwin's theory. These scientists view natural selection as one, but by no means the only, component of a much more complex process of life's development. There are researchers who believe that evolution from organisms to more complex ones is a sign that living organisms have an innate desire to move from simple forms to the most complex ones. Be that as it may, science is still far from a comprehensive understanding of the essence of evolution.

living planet

Ours has changed a lot over the billions of years of its development. Indeed, life forms and the planet itself develop in close relationship with each other. For example, the most ancient blue-green algae many millions of years ago became the main source of oxygen in the atmosphere, without which more complex forms of life simply could not exist. Some scientists argue that our planet and its - is a huge living organism. The idea of ​​a living planet is usually associated with the name of Gaia, the ancient Greek goddess of the Earth.

Man is responsible for everything

Now we can shape the environment at our will and thereby influence the further evolution of man. We can also actively influence the future of the Earth and all life on it. However, we are only just beginning to realize the enormous responsibility that lies with us. There are several options for further development.

The bones of dinosaurs and amazing extinct animals have been found in different eras of human history. In the absence of science, legends about giants or dragons were composed from the bones found. Only modern people with the development of science could study the main stages of the development of life on Earth from paleontological finds.

Earth formation

Our planet was formed about 4.5 billion years ago from stellar dust and solid particles. With an increase in 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 thickened and began to cool. The hot mantle maintains heat so far, preventing the Earth from turning into a block of ice.

For a long time the planet was in a lifeless state. The atmosphere was filled with various gases and contained no oxygen. Due to the release of a large amount of steam from the bowels of the Earth and gravity, dense clouds began to form. Intense rains contributed to the emergence of the World Ocean, in which life originated.

Rice. 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 connected with geological eons and eras. An eon is a large segment of geological history that combines several eras. In turn, eras are subdivided into periods. Each era is characterized by an individual development of the animal and plant world, which often depended on the climate, the state of the earth's crust, and underground activities.

Rice. 2. Eras of the geological history of the Earth.

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

TOP 1 articlewho read along with this

There are a lot of theories of the origin of life on Earth, among them the hypothesis of the origin of life from an ice cube, and the theory of the extraterrestrial origin of life, and even the origin of life in places of volcanic activity.

Some of them have scientific evidence, others have not yet been thoroughly studied. One way or another, but of all the existing theories, most of the scientific world supports the theory of Charles Darwin, who suggested that life on Earth originated in a reservoir.

According to Darwin's theory, the Earth began to evolve about 4.5 billion years ago, when the first chemical reactions of erupting lava, rich in high-energy substances and metals, with water (still sterile at that time) began to occur at the bottom of the ocean near places of increased volcanic activity, due to which the formation of new molecules. Thus, for many decades the ocean acted as a "chemical kitchen", where the main dish - life - was made.

So far, none of the scientists can answer the question of what the first living organism was - the ancient ancestor of the three main branches of the tree of life: I - eukaryotes (animals, plants, fungi), II - prokaryotes (bacteria), III - archaebacteria (arranged like prokaryotes, but with a different lipid structure).

The entire evolution of life on Earth took place in several stages - eras, subdivided into periods. So, in the Archean era (3.5-2.6 billion years ago) - the most ancient era - the first biological breakthrough occurred - the transition from prokaryotes - non-nuclear organisms to nuclear ones.

Gradually absorbing prokaryotic cells and reacting with them, eukaryotes have complicated their structure and transformed into complexly organized eukaryotic cells. So aerobic bacteria became mitochondria, and photosynthetic bacteria became chloroplasts. This period was the beginning of the formation of heterotrophs in water and on land. Soil appeared, and the accumulation of oxygen and carbon dioxide began in the atmosphere.

The Proterozoic era (2.6 billion - 570 million years ago) is the next huge stage that reflects the evolution of life on Earth. During it, the beginning of sexual reproduction was laid, which, in turn, led to the emergence of new species of plants and animals. It was in this period that multicellularity arose, as a result of which simple coelenterates, worms, sponges and other primitive organisms appeared.

The emergence of multicellular organisms is considered the second biological breakthrough. Throughout the Proterozoic, due to the activity of oceanic plankton, active oxygen accumulated in the atmosphere, resulting in a decrease in the amount of carbon. Thus, the Archean and Proterozoic era (Cryptozoic era) were a period of hidden life on Earth.

The period of the end of the Proterozoic - the beginning of the Paleozoic eras (600 million years ago) became the third biological breakthrough. At this time, the laying of the skeleton occurred in living organisms. Throughout the Paleozoic era (570-230 million years ago) there was an intensive development of flora and fauna. Fish appeared, animals gradually emerged from the water onto land.

As a result of the reduction of the seas and the rise of the land, the climate changed, and the first forests of horsetails, club mosses and giant ferns appeared on the surface of the Earth. Such a change in the plant world led to the emergence of new species of animals - reptiles, from which mammals and humans later appeared. By the way, people got five fingers on each limb from the first reptile diplovertebron.

The geological era (230-67 million years ago) is divided into periods: Triassic, Jurassic, Cretaceous and is called the era of reptiles, since their mass distribution occurred in this era. At the beginning of the Mesozoic, there was a sharp change in climate - a drought, because of this, many animals moved to the ocean.

Their limbs atrophied and the first dolphins appeared - ichthyosaurs and plesiosaurs. In the Triassic, carnivorous and herbivorous dinosaurs appeared. From the dinosaurs later appeared the first birds - Archeopteryx (Jurassic period). And real birds, albeit with teeth, appeared already in the Cretaceous period.

During the same period, volcanic activity was greatly intensified, due to which the climate became more humid. This led to the emergence of new types of dinosaurs: hadrosaurs, ceratopsians, therapods, including tyrannosaurs.

Higher mammals also appeared: marsupials and placentals. Mollusks, elasmosaurs, and crocodile-like pliosaurs bred in the water. Marine "inhabitants" began to accumulate calcium carbonate, due to which the chalk, limestone and marl deposited at the bottom actively neutralized carbon dioxide in the atmosphere.

At the end of the Mesozoic period, there was a mass extinction of flora and fauna. Dinosaurs, pterosaurs and 80% of the entire marine "population" disappeared completely. The cause of this catastrophe is considered to be the fall of an asteroid or the nucleus of a comet, but all these are assumptions ... At this stage, the evolution of life on Earth did not stop, but a new era began - the Cenozoic.

The Cenozoic era in which we still live (67 million years ago until today) became the era of flowering plants, insects, birds and mammals. It is divided into two periods: Tertiary and Quaternary.

In the Tertiary period (67-3 million years ago), tropical and subtropical forests appeared in the plant world, and the first primates appeared in the animal world, which became the progenitors of great apes. In the middle of the Tertiary period, all kinds of animals and plants already existed on the surface of the Earth, a gradual steppe stepping of the land began, which led to a reduction in forest areas.

At the same time, some anthropoid monkeys went deep into the forests, while others, on the contrary, descended to the ground and began its active conquest. It is this type of monkey that is the ancestors of people who appeared already at the end of the Tertiary period.

In the Chervertic period (3 million years ago - our time), many animals died out, in which the hunting instinct developed by ancient people played a big role. Today's way of life (agriculture and pastoralism) was a consequence of the "Neolithic revolution", which took place about 10 thousand years ago. It was then that people abandoned gathering and hunting.

As you can see, the evolution of life on Earth is a very long and rather complicated process. But it is to this process that we owe our life and existence.