On land, the variety of reptiles increased. Their hind limbs have become more developed than the front ones. The ancestors of modern lizards and turtles also appeared in the Triassic period. In the Triassic period, the climate of individual territories was not only dry, but also cold. As a result of the struggle for existence and natural selection, the first mammals appeared from some predatory reptiles, which were no more than rats. It is assumed that they, like modern platypuses and echidnas, were oviparous.

Plants

Reptiles penitent in jurassic spread not only on land, but also in water and air environment. Flying lizards are widespread. In the Jurassic period, the very first birds, Archeopteryx, also appeared. As a result of the flowering of spore and gymnosperms, the size of the body of herbivorous reptiles increased excessively, some of them reached a length of 20-25 m.

Plants

Thanks to warm and humid climate in the Jurassic, tree-like plants flourished. In the forests, as before, gymnosperms and fern-like plants dominated. Some of them, such as sequoia, have survived to this day. The first flowering plants that appeared in the Jurassic had a primitive structure and were not widespread.

Climate

IN Cretaceous the climate has changed dramatically. Cloudiness has significantly decreased, and the atmosphere has become dry and transparent. As a result of this, the sun's rays fell directly on the leaves of plants. material from the site

Animals

On land, the class of reptiles still maintained its dominance. Predatory and herbivorous reptiles increased in size. Their bodies were covered with armor. The birds had teeth, but otherwise they were close to modern birds. In the second half Cretaceous representatives of the subclass of marsupials and placentals appeared.

Plants

The climatic changes of the Cretaceous period had a negative impact on ferns and gymnosperms, and their numbers began to decrease. But angiosperms, on the contrary, multiplied. By the middle of the Cretaceous, many families of monocots and dicots had developed. angiosperms. For its diversity and appearance they came close to modern flora in many ways.

The history of the Earth is four and a half billion years old. This huge period of time is divided into four eons, which in turn are divided into eras and periods. The final fourth eon - Phanerozoic - includes three eras:

  • Paleozoic;
  • Mesozoic;
  • Cenozoic.
significant for the appearance of dinosaurs, the birth of the modern biosphere and significant geographical changes.

Periods of the Mesozoic Era

Ending Paleozoic era marked by the extinction of animals. The development of life in the Mesozoic era is characterized by the appearance of new types of creatures. First of all, these are dinosaurs, as well as the first mammals.

The Mesozoic lasted one hundred and eighty-six million years and consisted of three periods, such as:

  • Triassic;
  • Jurassic;
  • chalky.

The Mesozoic period is also characterized as the era of global warming. There have also been significant changes in the tectonics of the Earth. It was at that time that the only existing supercontinent broke up into two parts, which subsequently divided into the continents that exist in the modern world.

Triassic

The Triassic period is the first stage of the Mesozoic era. The Triassic lasted for thirty-five million years. After the catastrophe that occurred at the end of the Paleozoic on Earth, conditions are observed that are little conducive to the prosperity of life. A tectonic fault occurs, active volcanoes and mountain peaks are formed.

The climate becomes warm and dry, in connection with which deserts form on the planet, and the level of salt in water bodies rises sharply. However, it is at this unfavorable time that mammals and birds appear. In many respects, this was facilitated by the absence of clearly defined climatic zones and the maintenance of the same temperature throughout the globe.

Fauna of the Triassic

The Triassic period of the Mesozoic is characterized by a significant evolution of the animal world. It was during the Triassic period that those organisms arose that subsequently shaped the appearance of the modern biosphere.

Cynodonts appeared - a group of lizards, which was the ancestor of the first mammals. These lizards were covered with hair and had strongly developed jaws, which helped them to eat. raw meat. Cynodonts laid eggs, but females fed their young with milk. In the Triassic, the ancestors of dinosaurs, pterosaurs and modern crocodiles, the archosaurs, also originated.

Due to the arid climate, many organisms have changed their habitat to aquatic. Thus, new species of ammonites, mollusks, as well as bony and ray-finned fish appeared. But the main inhabitants sea ​​depths there were predatory ichthyosaurs, which, as they evolved, began to reach gigantic sizes.

By the end of the Triassic, natural selection did not allow all the animals that appeared to survive, many species could not withstand competition with others, stronger and faster. Thus, by the end of the period, thecodonts, the progenitors of the dinosaurs, dominated the land.

Plants during the Triassic period

The flora of the first half of the Triassic did not differ significantly from the plants of the end of the Paleozoic era. Grow in abundance in the water different types algae, seed ferns and ancient conifers are widely distributed on land, and lycosid plants are widespread in coastal zones.

By the end of the Triassic, the land was covered with a cover herbaceous plants, which greatly contributed to the emergence of a variety of insects. Also appeared plants of the mesophytic group. Some cycad plants have survived to this day. It is growing in the Malay Archipelago zone. Most of the plant varieties grew on the coastal areas of the planet, and conifers prevailed on land.

Jurassic period

This period is the most famous in the history of the Mesozoic era. Jura - European mountains that gave the name to this time. Sedimentary deposits of that era have been found in these mountains. The Jurassic period lasted fifty-five million years. Geographical significance acquired due to the formation of modern continents (America, Africa, Australia, Antarctica).

The separation of the two continents of Laurasia and Gondwana that existed until that moment served to form new bays and seas and raise the level of the world's oceans. This had a positive effect on making it more humid. The air temperature on the planet dropped and began to correspond to moderate and subtropical climate. Such climatic changes largely contributed to the development and improvement of the animal and plant world.

Animals and plants of the Jurassic period

The Jurassic is the era of the dinosaurs. Although other forms of life also evolved and acquired new forms and types. The seas of that period were filled with many invertebrates, the body structure of which is more developed than in the Triassic. Have been ubiquitous bivalves and intrashell belemnites, the length of which reached three meters.

The insect world has also received evolutionary growth. The appearance of flowering plants provoked the appearance of pollinating insects. New species of cicadas, beetles, dragonflies and other terrestrial insects arose.

Climatic changes that occurred during the Jurassic period led to abundant rainfall. This, in turn, gave impetus to the spread of lush vegetation on the surface of the planet. Herbaceous fern and ginkgo plants predominated in the northern zone of the earth. southern belt were tree ferns and cycads. In addition, the Earth was filled with various coniferous, cordaite and cycad plants.

Age of dinosaurs

In the Jurassic period of the Mesozoic, reptiles reached their evolutionary peak, ushering in the era of dinosaurs. The seas were dominated by giant dolphin-like ichthyosaurs and plesiosaurs. If ichthyosaurs were inhabitants of an exclusively aquatic environment, then plesiosaurs from time to time needed access to land.

Dinosaurs living on land were striking in their diversity. Their sizes ranged from 10 centimeters to thirty meters, and they weighed up to fifty tons. Among them, herbivores predominated, but there were also ferocious predators. A huge number of predatory animals provoked the formation of some defense elements in herbivores: sharp plates, spikes and others.

Air space jurassic filled with dinosaurs that could fly. Although for the flight they needed to climb a hill. Pterodactyls and other pterosaurs flocked and hovered above the ground in search of food.

Cretaceous period

When choosing a name for the next period leading role played, formed in the deposits of dying invertebrate organisms, writing chalk. The period called the Cretaceous was the final mesozoic era. This time lasted eighty million years.

The formed new continents are moving, and the Earth's tectonics is increasingly acquiring a familiar look. modern man. The climate became noticeably colder, at that time the ice caps of the northern and south pole. There is also a division of the planet into climatic zones. But in general, the climate remained warm enough, which was facilitated by the greenhouse effect.

Cretaceous biosphere

In reservoirs, belemnites and mollusks continue to evolve and spread, and also develop sea ​​urchins and the first crustaceans.

In addition, fish with a hard-bone skeleton actively develop in reservoirs. Insects and worms progressed strongly. On land, the number of vertebrates increased, among which reptiles occupied the leading positions. They actively consumed vegetation earth's surface and destroyed each other. In the Cretaceous period, the first snakes arose, which lived both in water and on land. Birds, which began to appear at the end of the Jurassic period, became widespread and actively developed during the Cretaceous period.

Among the vegetation, flowering plants have received the greatest development. Spore plants died out due to the characteristics of reproduction, giving way to more progressive ones. At the end of this period, gymnosperms noticeably evolved and began to be replaced by angiosperms.

End of the Mesozoic Era

The history of the Earth has two that served as a mass extinction of the animal world of the planet. The first, Permian catastrophe was the beginning of the Mesozoic era, and the second marked its end. Most of the animal species that actively evolved in the Mesozoic died out. IN aquatic environment ammonites, belemnites, bivalve mollusks ceased to exist. Dinosaurs and many other reptiles disappeared. Many species of birds and insects also disappeared.

To date, there is no proven hypothesis about what exactly served as the impetus for the mass extinction of the fauna in the Cretaceous period. There are versions about the negative impact of the greenhouse effect or about radiation caused by a powerful cosmic explosion. But most scientists are inclined to believe that the cause of extinction was the fall of a gigantic asteroid, which, when it hit the Earth's surface, raised a mass of substances into the atmosphere that closed the planet from sunlight.

Which he followed. The Mesozoic era is sometimes referred to as the "era of the dinosaurs" because these animals were the dominant representatives for much of the Mesozoic.

After the Permian mass extinction wiped out more than 95% of ocean life and 70% of land species, a new Mesozoic era began about 250 million years ago. It consisted of the following three periods:

Triassic period, or Triassic (252-201 million years ago)

The first big changes were seen in the type that dominated the Earth. Most of the flora that survived the Permian extinction became plants containing seeds, such as gymnosperms.

Cretaceous period, or Cretaceous (145-66 million years ago)

The last period of the Mesozoic was called the Cretaceous. There was an increase in flowering land plants. They were helped by newly appeared bees and warm climatic conditions. coniferous plants were still numerous during the Cretaceous.

As far as Cretaceous marine animals are concerned, sharks and rays became commonplace. survivors of the Permian extinction, such as starfish, were also abundant during the Cretaceous.

On land, the first small mammals began to develop in the Cretaceous period. First, marsupials appeared, and then other mammals. Appeared more birds and there were more reptiles. The dominance of dinosaurs continued, and the number of carnivorous species increased.

At the end of the Cretaceous and Mesozoic, another thing happened. This disappearance is usually called K-T extinction(Cretaceous-Paleogene extinction). It wiped out all dinosaurs except birds and many other life forms on Earth.

Exist different versions as to why the mass extinction occurred. Most scientists agree that it was some kind of catastrophic event that caused this extinction. Various hypotheses include massive volcanic eruptions that sent air into the atmosphere. great amount dust, which reduced the amount of sunlight reaching the Earth's surface and thereby caused the death of photosynthetic organisms such as plants and those who depended on them. Others believe that a meteorite fell to Earth, and the dust covered sunlight. As the plants and animals that fed on them died out, this led to predators such as carnivorous dinosaurs also dying for lack of food.

The Mesozoic era is subdivided into the Triassic, Jurassic and Cretaceous periods.

After the intense mountain building of the Carboniferous and Permian periods, the Triassic period is characterized by relative tectonic calm. Only at the end of the Triassic, on the border with the Jura, does the ancient Cimmerian phase of the Mesozoic warehouse appear.

frequency. Volcanic processes in the Triassic are quite active, but their centers move to the Pacific geosynclinal belts and to the Mediterranean geosyncline. In addition, the formation of traps continues on the Siberian platform (Tunguska basin).

Both the Permian and the Triassic are characterized by a strong reduction in the area of ​​epicontinental seas. Vast expanses of present-day continents are almost devoid of Triassic marine sediments. The climate is continental. The animal world takes on the appearance that later became characteristic of the Mesozoic era as a whole. The sea is dominated by cephalopods (ammonites) and lamellar-gill mollusks; sea ​​lizards appear, already dominant on land. Gymnosperms (cycads, conifers and gingkoves) predominate among plants.

The Triassic deposits are poor in minerals (coal, building materials).

The Jurassic period is tectonically more intense. At the beginning of the Jurassic, the ancient Cimmerian, and at the end of the new Cimmerian phase of the Mesozoic (Pacific) folding appears. Within the northern continental platforms and zones previously subjected to mountain building, deep faults develop in the northern hemisphere and depressions are formed. In the southern hemisphere, the disintegration of the mainland Gondwana begins. Volcanism is actively manifested in geosynclinal belts.

Unlike the Triassic, the Jurassic is characterized by transgressions. Thanks to them, the climate becomes less continental. During this period, the further development of the flora of gymnosperms takes place.

Significant development of the fauna was expressed in a noticeable increase and specialization of species of marine and terrestrial animals. The development of lizards continues (predatory, herbivorous, marine, terrestrial, flying), the first species of birds and mammals appear. Ammonite cephalopods dominate the sea, new species of sea urchins, lilies, etc.

The main minerals found in the Jurassic deposits are oil, gas, oil shale, coal, phosphorites, iron ores, bauxites and a number of others.

In the Cretaceous, intense mountain building takes place, called the Laramian phase of the Mesozoic folding. The Laramian orogeny developed with the greatest force at the boundary of the Lower and Upper Cretaceous, when extensive geosynclines arose in the Pacific geosynclines. mountainous countries. In the Mediterranean belt, this phase was preliminary and preceded the main orogeny, which developed later in the Cenozoic era.

For the southern hemisphere, in addition to mountain building in the Andes, the Cretaceous period was marked by further breaks in the Gondwana mainland, subsidence of large areas of land and the formation of depressions in the Indian Ocean and the South Atlantic Ocean. Faults in the earth's crust and mountain building were accompanied by the manifestation of volcanism.

Reptiles dominate the animal world of the Cretaceous period and many species of birds appear. There are few more mammals. Ammonites and lamellar mollusks, sea urchins, lilies, corals continue to dominate in the sea, and foraminifers are widely developed, from the shells of which (partially) the formation of white writing chalk occurred. The flora of the Lower Cretaceous has a typical Mesozoic character. Gymnosperms continue to predominate in it, but in the Upper Cretaceous, the dominant role passes to angiosperms, close to modern ones.

On the platforms, Cretaceous deposits are distributed approximately in the same place as Jurassic ones and contain the same complex of minerals.

Considering the Mesozoic era as a whole, it should be noted that “it was marked by new manifestations of orogenic phases that were most developed in the Pacific geosynclinal belts, for which mesozoic era orogeny is often called the Pacific orogeny. In the Mediterranean geosynclinal belt, this orogeny was preliminary. Young mountain structures joined as a result of geosyncline closure increased the size of hard sections earth's crust. At the same time, mainly in the southern hemisphere, the opposite process began to develop - the disintegration of the ancient continental mass of Gondwana. Volcanic activity was no less intense in the Mesozoic than in the Paleozoic. Great changes have taken place in the composition of flora and fauna. Among terrestrial animals, reptiles flourished and declined at the end of the Cretaceous. Ammonites, belemnites and a number of other animals passed the same course of development in the seas. In the second half of the Cretaceous, an angiosperm flora appears in place of the gymnosperms that dominated the Mesozoic.

Of the minerals formed in the Mesozoic era, oil, gas, coal, phosphorites and various ores are of the greatest importance.

Mesozoic era- the second in the Phanerozoic eon.

Its time frame is 252-66 million years ago.

Periods of the Mesozoic Era

This era was separated in 1841 by John Phillips, a geologist by profession. It is divided into only three separate periods:

  • Triassic - 252-201 million years ago;
  • Jurassic - 201-145 million years ago;
  • Cretaceous - 145-66 million years ago.

Processes of the Mesozoic Era

Mesozoic era. triassic period photo

Pangea is divided first into Gondwana and Lavlasia, and then into smaller continents, the contours of which already clearly resemble modern ones. Formed within the continents big lakes and the sea.

Characteristics of the Mesozoic era

At the end of the Paleozoic era, there was a mass extinction of most of the living beings on the planet. This greatly influenced the development of later life. Pangea lasted for a long time. It is from its formation that many scientists count the beginning of the Mesozoic.

Mesozoic era. Jurassic period photo

Others attribute the formation of Pangea to the end of the Paleozoic era. In any case, life originally developed on one supercontinent, and this was actively promoted by a pleasant, warm climate. But over time, Pangea began to separate. Of course, this was reflected primarily in animal life, and mountain ranges appeared that have survived to this day.

Mesozoic era. Cretaceous period photo

The end of the era under consideration was marked by another major extinction. It is most often associated with the fall of the astroid. On the planet, half of the species were destroyed, including terrestrial dinosaurs.

Mesozoic life

The diversity of plant life in the Mesozoic reaches its climax. Many forms of reptiles have developed, new larger and smaller species have formed. This is also the period of the appearance of the first mammals, which, however, could not yet compete with dinosaurs, and therefore remained at the back of the food chain.

Plants of the Mesozoic Era

With the end of the Paleozoic, ferns, club mosses and tree horsetails die out. They were replaced in the Triassic period by conifers and other gymnosperms. In the Jurassic, gymnosperms already die out and woody angiosperms appear.

Mesozoic era. photo periods

Abundant vegetation covers the entire land, the predecessors of pines, cypresses, mammoth trees appear. In the Cretaceous period, the first plants with flowers developed. They had close contact with insects, one without the other, in fact, did not exist. Therefore, for a short time they have spread to all corners of the planet.

Animals of the Mesozoic Era

Great development is observed in reptiles and insects. The dominant position on the planet is taken over by reptiles, they are represented by a variety of species and continue to develop, but have not yet reached the peak of their size.

Mesozoic era. first birds photo

In the Jurassic, the first pangolins that can fly are formed, and in the Cretaceous, reptiles begin to grow rapidly, and reach incredible size. Dinosaurs were and are some of the most amazing life forms on the planet and at times reached a weight of 50 tons.


Mesozoic era. first photo mammals

By the end of the Cretaceous period, due to the aforementioned catastrophe or other possible factors considered by scientists, herbivorous and carnivorous dinosaurs. But small reptiles still survived. They still lived in the tropics (crocodiles).

IN water world changes are also taking place - large lizards and some invertebrates are disappearing. Adaptive radiation of birds and other animals begins. Mammals that appeared in the Triassic period occupy free ecological niches and are actively developing.

Aromorphoses of the Mesozoic era

The Mesozoic was marked by an abundant change in fauna and flora.

  • plant aromorphosis. Vessels appeared that perfectly conduct water and other nutrients. Some plants developed a flower that allowed them to attract insects, and this contributed to the rapid spread of some species. The seeds "acquired" a shell that protected them until they were fully ripe.
  • Aromorphoses of animals. Birds appeared, although this was preceded by significant changes: the acquisition of spongy lungs, the loss of the aortic arch, the division of blood flow, the acquisition of a septum between the ventricles of the heart. Mammals also appeared and developed due to a number of important factors: the division of blood flow, the appearance of a four-chambered heart, the formation of wool, intrauterine development of offspring, feeding offspring with milk. But mammals would not have survived without another important advantage: the development of the cerebral cortex. This factor led to the possibility of adapting to different conditions environment and, if necessary, change behavior.

The climate of the Mesozoic era

The warmest climate in the history of the planet in the Phanerozoic eon is precisely the Mesozoic. There were no frosts ice ages, sudden glaciations of land and seas. Life could and flourished in full force. Significant differences in temperature in different regions no planet was seen. Zoning existed only in the northern hemisphere.

Mesozoic era. aquatic life photo

The climate was divided into tropical, subtropical, warm temperate and cool temperate. As for humidity, at the beginning of the Mesozoic the air was mostly dry, and towards the end it was humid.

  • The Mesozoic era is the period of the formation and extinction of dinosaurs. This era is the warmest of all in the Phanerozoic. Flowers appeared in the last period of this era.
  • In the Mesozoic, the first mammals and birds appeared.

Results

Mesozoic is a time of significant changes on the planet. If the great extinction had not happened at that time, dinosaurs may still have been part of the animal kingdom, or maybe not. But in any case, they brought significant changes to the world by becoming part of it.

At this time, birds and mammals appear, life is raging in the water, on the ground and in the air. The same goes for vegetation. Flowering plants, the appearance of the first predecessors of modern coniferous trees played an indispensable role in the development of modern life.