Who lived in the Mesozoic era. Mesozoic era, Mesozoic. Plants of the Mesozoic era

Which was followed by . The Mesozoic Era is sometimes called the "Age of the Dinosaurs" because these animals were the dominant species throughout much of the Mesozoic.

After the Permian mass extinction wiped out more than 95% of ocean life and 70% terrestrial species, the 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 noticed in the type that dominated the Earth. Most of the flora that survived the Permian extinction were seed-bearing plants such as gymnosperms.

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

The last period of the Mesozoic was called the Cretaceous. The growth of flowering land plants occurred. They were helped by newly appeared bees and warm climatic conditions. Coniferous plants were still numerous during the Cretaceous.

In terms of Cretaceous marine animals, sharks and rays became commonplace. Survivors of the Permian extinction, such as starfish, were also abundant during the Cretaceous.

First on land small mammals began to develop during 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 extinction is commonly called the K-T extinction (Cretaceous-Paleogene extinction). It destroyed all dinosaurs except birds and many other life forms on Earth.

There are different versions as to why the mass disappearance occurred. Most scientists agree that there was some kind of catastrophic event that caused this extinction. Various hypotheses include massive volcanic eruptions that released huge amounts of dust into the atmosphere, reducing the amount of sunlight reaching the Earth's surface and thereby causing the death of photosynthetic organisms such as plants and those that depended on them. Others believe that a meteorite fell to Earth and the dust covered it. sunlight. Because the plants and animals that fed on them died out, this led to predators such as carnivorous dinosaurs also dying due to lack of food.

The Mesozoic consists of three periods: Triassic, Jurassic, Cretaceous.

In the Triassic most of The land was above sea level, the climate was dry and warm. Due to the very dry climate in the Triassic, almost all amphibians disappeared. Therefore, the flourishing of reptiles began, which were adapted to drought (Fig. 44). Among plants in the Triassic, strong development was achieved gymnosperms.

Rice. 44. Various types of reptiles of the Mesozoic era

Of the Triassic reptiles, turtles and hatteria have survived to this day.

The hatteria preserved on the islands of New Zealand is a true “living fossil.” Over the past 200 million years, hatteria has remained almost unchanged and, like its Triassic ancestors, has retained the third eye located in the roof of the skull.

Among reptiles, the rudiment of the third eye is preserved in lizards agamas and batbats.

Along with the undoubted progressive features in the organization of reptiles, there was one very significant imperfect feature - inconsistent body temperature. In the Triassic period, the first representatives of warm-blooded animals appeared - small primitive mammals - tricodonts. They originated from ancient beast-toothed lizards. But rat-sized tricodonts could not compete with reptiles, so they did not spread widely.

Yura named after a French city located on the border with Switzerland. During this period, the planet was “conquered” by dinosaurs. They mastered not only land, water, but also air. There are currently 250 known species of dinosaurs. One of the most characteristic representatives of dinosaurs was the giant brachiosaurus. It reached a length of 30 m, a weight of 50 tons, had a small head, a long tail and neck.

IN Jurassic period various types of insects and the first bird appear - Archeopteryx. Archeopteryx is the size of a crow. Its wings were poorly developed, it had teeth, and a long tail covered with feathers. In the Jurassic period of the Mesozoic there were many reptiles. Some of their representatives began to adapt to life in water.

The rather mild climate favored the development of angiosperms.

Chalk- the name was given because of thick chalk deposits formed from the remains of shells of small marine animals. During this period, angiosperms appear and spread extremely quickly, and gymnosperms are replaced.

The development of angiosperms during this period was associated with the simultaneous development of pollinating insects and insect-eating birds. Angiosperms have developed a new reproductive organ - a flower, which attracts insects with its color, smell and nectar reserves.

At the end of the Cretaceous period, the climate became colder, and the vegetation of the coastal lowlands died. Herbivores died along with the vegetation, carnivorous dinosaurs. Large reptiles (crocodile) are preserved only in the tropical zone.

In conditions of a sharply continental climate and general cooling, warm-blooded animals - birds and mammals - received exceptional advantages. The acquisition of viviparity and warm-bloodedness were the aromorphoses that ensured the progress of mammals.

During the Mesozoic period, the evolution of reptiles developed in six directions:

1st direction - turtles (appeared in the Permian period, have a complex shell fused with the ribs and breast bones);

5th direction - plesiosaurs (sea lizards with a very long neck, making up more than half of the body and reaching a length of 13-14 m);

6th direction - ichthyosaurs (lizard fish). Appearance looks like a fish and a whale, short neck, fins, swims with the help of a tail, legs control movement. Intrauterine development - live birth of offspring.

At the end of the Cretaceous period, during the formation of the Alps, climate change led to the death of many reptiles. During excavations, the remains of a bird the size of a pigeon, with the teeth of a lizard, which had lost the ability to fly, were discovered.

Aromorphoses that contributed to the appearance of mammals.

1. The increasing complexity of the nervous system and the development of the cerebral cortex influenced changes in animal behavior and adaptation to the living environment.

2. The spine was divided into vertebrae, the limbs were located from the abdominal part towards the back.

3. For intrauterine bearing of cubs, the female has developed a special organ. The cubs were fed milk.

4. To preserve body heat, hair appeared.

5. There was a division into the systemic and pulmonary circulation, and warm-bloodedness appeared.

6.Lungs have developed with numerous bubbles that enhance gas exchange.

1. Periods of the Mesozoic era. Triassic. Yura. Bor. Tricodonts. Dinosaurs. Archosaurs. Plesiosaurs. Ichthyosaurs. Archeopteryx.

2. Aromorphoses of the Mesozoic.

1.What plants were widespread in the Mesozoic? Explain the main reasons.

2. Tell us about the animals that developed in the Triassic.

1.Why is the Jurassic period called the period of dinosaurs?

2. Discuss aromorphosis, which is the cause of the appearance of mammals.

1. In what period of the Mesozoic did the first mammals appear? Why weren't they widespread?

2.Name the species of plants and animals that developed during the Cretaceous period.

In what period of the Mesozoic did these plants and animals develop? Opposite the corresponding plants and animals, put the capital letter of the period (T - Triassic, Y - Jurassic, M - Cretaceous).

1.Angiosperms.

2. Tricodonts.

4. Eucalyptus trees.

5. Archeopteryx.

6. Turtles.

7. Butterflies.

8. Brachiosaurs.

9. Hatterias.

11. Dinosaurs.

Eras. Lasted for 56 million years. Began 201 million years ago and ended 145 million years ago. The geochronological scale of the history of the Earth of all eons, eras and periods is located.

The name “Jura” was given by the name of the mountain range of the same name in Switzerland and France, where deposits of this period were first discovered. Later, geological strata of the Jurassic period were discovered in many other places on the planet.

During the Jurassic period, the Earth almost completely recovered from the largest one in history. Various shapes life - marine organisms, land plants, insects and many animal species - begin to flourish and increase their species diversity. In the Jurassic period, dinosaurs reigned - large, and sometimes simply gigantic lizards. Dinosaurs existed almost anywhere and everywhere - in the seas, rivers and lakes, in swamps, forests, and open spaces. Dinosaurs have become so diverse and widespread that over millions of years of evolution, some of them began to differ radically from each other. Dinosaurs included both herbivores and carnivores. Some of them were the size of a dog, while others reached a height of more than ten meters.

One of the species of lizards in the Jurassic period became the ancestor of birds. Archeopteryx, which existed just at this time, is considered an intermediate link between reptiles and birds. In addition to lizards and giant dinosaurs, warm-blooded mammals already lived on earth. Mammals of the Jurassic period were mostly small in size and occupied rather insignificant niches in the living space of the earth of those times. Against the background of the prevailing number and diversity of dinosaurs, they were practically invisible. This will continue throughout the Jurassic and subsequent periods. Mammals will become the rightful masters of the Earth only after the Cretaceous-Paleogene extinction, when all dinosaurs disappear from the face of the planet, opening the way for warm-blooded animals.

Animals of the Jurassic period

Allosaurus

Apatosaurus

Archeopteryx

Barosaurus

Brachiosaurus

Diplodocus

Dryosaurs

Giraffatitan

Camarasaurus

Camptosaurus

Kentrosaurus

Liopleurodon

Megalosaurus

Pterodactyls

Rhamphorhynchus

Stegosaurus

Scelidosaurus

Ceratosaurus

To protect your home or property, you must use best systems security. Alarm systems can be found at http://www.forter.com.ua/ohoronni-systemy-sygnalizatsii/. In addition, here you can purchase intercoms, video cameras, metal detectors and much more.

Talking about Mesozoic era, we come to the main topic of our site. The Mesozoic era is also called the era average life. That rich, varied and mysterious life, which developed, changed and finally ended around 65 million years ago. Beginning around 250 million years ago. end about 65 million years ago
Mesozoic era lasted approximately 185 million years. It is usually divided into three periods:
Triassic
Jurassic period
Cretaceous period
The Triassic and Jurassic periods were much shorter than the Cretaceous, which lasted about 71 million years.

Georgaphy and tectonics of the planet in the Mesozoic era

At the end of the Paleozoic era, the continents occupied vast spaces. The land prevailed over the sea. All ancient platforms forming the land were raised above sea level and surrounded by folded mountain systems formed as a result of the Variscan folding. The East European and Siberian platforms were connected by newly emerged mountain systems Ural, Kazakhstan, Tien Shan, Altai and Mongolia; the land area increased greatly due to the formation mountain areas V Western Europe, as well as along the edges of the ancient platforms of Australia, North America, South America (Andes). IN Southern Hemisphere there was a huge area ancient continent Gondwana.
In the Mesozoic, the collapse of the ancient continent of Gondwana began, but in general the Mesozoic era was an era of relative calm, only occasionally and briefly disturbed by minor geological activity called folding.
With the onset of the Mesozoic, the subsidence of the land began, accompanied by the advance (transgression) of the sea. The continent of Gondwana split and broke up into separate continents: Africa, South America, Australia, Antarctica and the Indian Peninsula massif.

Within Southern Europe and South-West Asia, deep troughs began to form - geosynclines of the Alpine folded region. The same troughs, but on the oceanic crust, arose along the periphery of the Pacific Ocean. Transgression (advance) of the sea, expansion and deepening of geosynclinal troughs continued during the Cretaceous period. Only at the very end of the Mesozoic era did the rise of continents and the reduction of the area of ​​seas begin.

Climate in the Mesozoic era

Climate in different periods changed depending on the movement of continents. In general, the climate was warmer than it is now. However, it was approximately the same throughout the planet. There was never such a temperature difference between the equator and the poles as there is now. Apparently this is due to the location of the continents in the Mesozoic era.
Seas and mountain ranges appeared and disappeared. During the Triassic period the climate was arid. This is due to the location of the land, most of which was desert. Vegetation existed along the ocean shore and along river banks.
During the Jurassic period, when the continent of Gondwana split and its parts began to diverge, the climate became more humid, but remained warm and even. This climate change was the impetus for the development of lush vegetation and rich wildlife.
Seasonal temperature changes Triassic period began to have a noticeable effect on plants and animals. Certain groups of reptiles have adapted to cold seasons. It was from these groups that mammals arose in the Triassic, and somewhat later, birds. At the end of the Mesozoic era, the climate became even colder. Deciduous woody plants appear, which partially or completely shed their leaves during cold seasons. This feature plants are an adaptation to colder climates.

Flora in the Mesozoic era

At the beginning of the Cretaceous periods, gymnosperms were still widespread, but the first angiosperms, more advanced forms, were already appearing.
The flora of the Lower Cretaceous still resembles in composition the vegetation of the Jurassic period. Gymnosperms are still widespread, but their dominance ends at the end of this time. Even in the Lower Cretaceous, the most progressive plants suddenly appeared - angiosperms, the predominance of which characterizes the era of the new plant life. Which we know now.
Angiosperms, or flowering plants, occupy the highest level of the evolutionary ladder of the plant world. Their seeds are enclosed in a durable shell; there are specialized reproductive organs (stamen and pistil) assembled into a flower with bright petals and a calyx. Flowering plants appear somewhere in the first half of the Cretaceous period, most likely in a cold and dry mountain climate with large temperature differences. With the gradual cooling that began in the Cretaceous period, flowering plants captured more and more areas on the plains. Quickly adapting to the new environment, they developed at great speed.
In a relatively short time, flowering plants spread throughout the Earth and reached great diversity. From the end of the Early Cretaceous era, the balance of forces began to change in favor of angiosperms, and by the beginning of the Upper Cretaceous their superiority became widespread. Cretaceous angiosperms belonged to the evergreen, tropical or subtropical types, among them were eucalyptus, magnolia, sassafras, tulip trees, Japanese quince trees, brown laurels, walnut trees, plane trees, and oleanders. These heat-loving trees coexisted with the typical flora of the temperate zone: oaks, beeches, willows, and birches. This flora also included gymnosperms conifers (sequoias, pines, etc.).
For gymnosperms, this was a time of surrender. Some species have survived to this day, but their total numbers have been declining all these centuries. A definite exception is conifers, which are still found in abundance today. In the Mesozoic, plants made a great leap forward, surpassing animals in terms of development rates.

Fauna of the Mesozoic era.

Reptiles.

The oldest and most primitive reptiles were the clumsy cotylosaurs, which appeared at the beginning of the Middle Carboniferous and became extinct by the end of the Triassic. Among cotylosaurs, both small animal-eating and relatively large herbivorous forms (pareiasaurs) are known. The descendants of cotylosaurs gave rise to the entire diversity of the reptile world. One of the most interesting reptile groups, which developed from cotylosaurs, were beast-like (Synapsida, or Theromorpha); their primitive representatives (pelycosaurs) have been known since the end of the Middle Carboniferous. In the middle of the Permian period, the pelycosaurs that inhabited the territory of what is now North America die out, but in the European part they are replaced by more developed forms forming the order Therapsida.
The predatory theriodonts (Theriodontia) included in it have some similarities with mammals. By the end of the Triassic period, it was from them that the first mammals developed.
During the Triassic period, many new groups of reptiles appeared. These include turtles and ichthyosaurs (“fish lizards”), which are well adapted to life in the sea and look like dolphins. Placodonts, clumsy armored animals with powerful flat-shaped teeth adapted for crushing shells, and also plesiosaurs that lived in the seas, which had a relatively small head and long neck, wide body, flipper-like paired limbs and a short tail; plesiosaurs vaguely resemble giant turtles without a shell.

Dinosaurs

In the Triassic, they still competed with animals that survived the Permian catastrophe, but in the Jurassic and Cretaceous periods they confidently led in all ecological niches. Currently, about 400 species of dinosaurs are known.
Dinosaurs are represented by two groups, saurischia (Saurischia) and ornithischia (Ornithischia).
In the Triassic, the diversity of dinosaurs was not great. The very first famous dinosaurs were eoraptor And Herrerasaurus. The most famous of the Triassic dinosaurs are coelophysis And plateosaurus .
The Jurassic period is known for the most amazing diversity among dinosaurs; real monsters could be found, up to 25-30 m long (including tail) and weighing up to 50 tons. Of these giants, the most famous diplodocus And brachiosaurus. Also a prominent representative Jurassic fauna is bizarre stegosaurus. It can be unmistakably identified among other dinosaurs.
During the Cretaceous period, the evolutionary progress of dinosaurs continued. Of the European dinosaurs of this time, bipeds are widely known iguanodons, four-legged horned dinosaurs became widespread in America Triceratops similar to modern rhinoceroses. In the Cretaceous period, there were also relatively small armored dinosaurs - ankylosaurs, covered with a massive bony shell. All of these forms were herbivores, as were giant duck-billed dinosaurs such as Anatosaurus and Trachodon, which walked on two legs.
Except herbivores large group carnivorous dinosaurs also represented. All of them belonged to the group of lizards. A group of carnivorous dinosaurs are called terrapods. In the Triassic, this is Coelophysis - one of the first dinosaurs. In the Jurassic period, Allosaurus and Deinonychus reached their peak. In the Cretaceous period the most remarkable forms were such as Tyrannosaurus ( Tyrannosaurus rex), whose length exceeded 15 m, Spinosaurus and Tarbosaurus. All these forms, which turned out to be the greatest terrestrial predatory animals in the entire history of the Earth, moved on two legs.

Other reptiles of the Mesozoic era

At the end of the Triassic, the thecodonts also gave rise to the first crocodiles, which became abundant only in the Jurassic period (Steneosaurus and others). In the Jurassic period, flying lizards appeared - pterosaurs (Pterosaurids), also descended from thecodonts. Among the flying dinosaurs of the Jurassic, the most famous are Rhamphorhynchus and Pterodactylus; among the Cretaceous forms, the most interesting is the relatively very large Pteranodon. Flying lizards became extinct by the end of the Cretaceous.
In the Cretaceous seas, giant predatory lizards - mosasaurs, exceeding 10 m in length - became widespread. Among modern lizards, they are closest to monitor lizards, but differ from them, in particular, in their flipper-like limbs. By the end of the Cretaceous, the first snakes (Ophidia) appeared, apparently descended from lizards that led a burrowing lifestyle. Towards the end of the Cretaceous, there was a mass extinction of characteristic Mesozoic groups of reptiles, including dinosaurs, ichthyosaurs, plesiosaurs, pterosaurs and mosasaurs.

Cephalopods.

Belemnite shells are popularly known as “devil’s fingers.” Ammonites were found in such numbers in the Mesozoic that their shells are found in almost all marine sediments of this time. Ammonites appeared in the Silurian, they experienced their first flowering in the Devonian, but reached their highest diversity in the Mesozoic. In the Triassic alone, over 400 new genera of ammonites arose. Particularly characteristic of the Triassic were ceratids, which were widespread in the Upper Triassic sea basin. Central Europe, deposits of which in Germany are known as shell limestone. By the end of the Triassic, most ancient groups of ammonites died out, but representatives of the Phylloceratida survived in Tethys, the giant Mesozoic Mediterranean Sea. This group developed so rapidly in the Jurassic that the ammonites of this time surpassed the Triassic in the variety of forms. During the Cretaceous, cephalopods, both ammonites and belemnites, remained numerous, but during the Late Cretaceous the number of species in both groups began to decline. Among the ammonites at this time, aberrant forms appeared with an incompletely twisted hook-shaped shell with a shell elongated in a straight line (Baculites) and with a shell irregular shape(Heteroceras). These aberrant forms appeared, apparently, as a result of changes in the course of individual development and narrow specialization. The terminal Upper Cretaceous forms of some branches of ammonites are distinguished by sharply increased shell sizes. In one species of ammonite, the diameter of the shell reaches 2.5 m. Great importance Belemnites acquired in the Mesozoic era. Some of their genera, for example, Actinocamax and Belemnitella, are important fossils and are successfully used for stratigraphic division and accurate determination of the age of marine sediments. At the end of the Mesozoic, all ammonites and belemnites became extinct. Of the cephalopods with an external shell, only nautiluses have survived to this day. More widespread in modern seas are forms with internal shells - octopuses, cuttlefish and squids, distantly related to belemnites.

Other invertebrate animals of the Mesozoic era.

Tabulates and four-rayed corals were no longer present in the Mesozoic seas. Their place was taken six-rayed corals(Hexacoralla), whose colonies were active reef builders - the sea reefs they built are now widespread in Pacific Ocean. Some groups of brachiopods still developed in the Mesozoic, such as Terebratulacea and Rhynchonellacea, but the vast majority of them declined. Mesozoic echinoderms were represented by various species of crinoids, or crinoids (Crinoidea), which flourished in the shallow waters of the Jurassic and partly Cretaceous seas. However, the greatest progress has been made by sea urchins (Echinoidca); for today
Countless species of them have been described since the Mesozoic. Starfish (Asteroidea) and ophidra were abundant.
Compared to the Paleozoic era, bivalves also became widespread in the Mesozoic. Already in the Triassic, many new genera appeared (Pseudomonotis, Pteria, Daonella, etc.). At the beginning of this period we also meet the first oysters, which would later become one of the most common groups of mollusks in the Mesozoic seas. The appearance of new groups of mollusks continued in the Jurassic; the characteristic genera of this time were Trigonia and Gryphaea, classified as oysters. In the Cretaceous formations you can find funny types of bivalves - rudists, the goblet-shaped shells of which had a special cap at the base. These creatures settled in colonies, and in the Late Cretaceous they contributed to the construction of limestone cliffs (for example, the genus Hippurites). The most characteristic bivalves of the Cretaceous were mollusks of the genus Inoceramus; some species of this genus reached 50 cm in length. In some places there are significant accumulations of remains of Mesozoic gastropods (Gastropoda).
During the Jurassic period, foraminifera flourished again, surviving the Cretaceous period and reaching modern times. In general, single-celled protozoa were an important component in the formation of sedimentary
rocks of the Mesozoic, and today they help us establish the age of various layers. The Cretaceous period was also a time of rapid development of new types of sponges and some arthropods, particularly insects and decapods.

The rise of vertebrates. Fishes of the Mesozoic era.

The Mesozoic era was a time of unstoppable expansion of vertebrates. Of the Paleozoic fishes, only a few passed into the Mesozoic, as did the genus Xenacanthus, the last representative freshwater sharks Paleozoic, known from freshwater sediments of the Australian Triassic. Sea sharks continued to evolve throughout the Mesozoic; most modern genera were already represented in the seas of the Cretaceous, in particular Carcharias, Carcharodon, Isurus, etc. Ray-finned fish, which arose at the end of the Silurian, initially lived only in freshwater reservoirs, but with the Permian they begin to enter the seas, where they reproduce unusually and from the Triassic to the present day they retain a dominant position. Earlier we talked about Paleozoic lobe-finned fishes, from which the first land vertebrates developed. Almost all of them became extinct in the Mesozoic; only a few of their genera (Macropoma, Mawsonia) were found in Cretaceous rocks. Until 1938, paleontologists believed that lobe-finned animals became extinct by the end of the Cretaceous. But in 1938, an event occurred that attracted the attention of all paleontologists. An individual of a species of fish unknown to science was caught off the South African coast. Scientists who studied this unique fish came to the conclusion that it belongs to the “extinct” group of lobe-finned fish (Coelacanthida). Before
Currently, this species remains the only modern representative of ancient lobe-finned fish. It was named Latimeria chalumnae. Such biological phenomena are called “living fossils.”

Amphibians.

In some zones of the Triassic, labyrinthodonts (Mastodonsaurus, Trematosaurus, etc.) are still numerous. By the end of the Triassic, these “armored” amphibians disappeared from the face of the earth, but some of them apparently gave rise to the ancestors of modern frogs. It's about about the genus Triadobatrachus; To date, only one incomplete skeleton of this animal has been found in the north of Madagascar. True tailless amphibians are already found in the Jurassic
- Anura (frogs): Neusibatrachus and Eodiscoglossus in Spain, Notobatrachus and Vieraella in South America. In the Cretaceous, the development of tailless amphibians accelerates, but they reach their greatest diversity in the Tertiary period and today. In the Jurassic, the first tailed amphibians (Urodela) appeared, to which modern newts and salamanders belong. Only in the Cretaceous do their finds become more common, but the group reached its peak only in the Cenozoic.

The first birds.

Representatives of the class of birds (Aves) first appear in Jurassic deposits. The remains of Archaeopteryx, the well-known and so far only known first bird, were found in lithographic shales of the Upper Jurassic, near the Bavarian city of Solnhofen (Germany). During the Cretaceous period, the evolution of birds proceeded at a rapid pace; The characteristic genera of this time were Ichthyornis and Hesperornis, which still had serrated jaws.

The first mammals.

The first mammals (Mammalia), modest animals no larger than a mouse, descended from animal-like reptiles in the Late Triassic. Throughout the Mesozoic they remained few in number and by the end of the era the original genera were largely extinct. The most ancient group of mammals were the triconodonts (Triconodonta), to which the most famous of the Triassic mammals, Morganucodon, belongs. During the Jurassic period, a number of new groups of mammals appeared.
Of all these groups, only a few survived the Mesozoic, the last of which died out in the Eocene. The ancestors of the main groups of modern mammals - marsupials (Marsupialia) and placentals (Placentalid) were Eupantotheria. Both marsupials and placentals appeared at the end of the Cretaceous period. Most ancient group Placentals are insectivores (Insectivora), which have survived to this day. Powerful tectonic processes of Alpine folding, which erected new mountain ranges and changed the shape of the continents, radically changed the geographical and climatic conditions. Almost all Mesozoic animal groups and plant kingdom retreat, die out, disappear; arises on the ruins of the old new world, the world of the Cenozoic era, in which life receives a new impetus for development and, in the end, living species of organisms are formed.

The Mesozoic era is divided 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 quiescence. Only at the end of the Triassic, on the border with the Jurassic, does the ancient Cimmerian phase of the Mesozoic fold appear

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

Both the Permian and Triassic were characterized by a strong reduction in the area of ​​epicontinental seas. Vast areas of modern continents are almost devoid of Triassic marine sediments. The climate is continental. 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 elasmobranch molluscs; sea ​​lizards appear, already dominating the land. Among the plants, gymnosperms predominate (cycads, conifers and gingcaes).

Triassic deposits are poor in mineral resources (coal, building materials).

The Jurassic period is tectonically more intense. At the beginning of the Jurassic, the Old Cimmerian, and at the end of the New Cimmerian, phases of Mesozoic (Pacific) folding appeared. Within the northern continental platforms and areas previously subject to mountain building, deep faults develop and depressions form in the northern hemisphere. In the southern hemisphere, the continent of Gondwana begins to disintegrate. 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, further development of the flora of gymnosperms occurs.

The 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. The sea is dominated by cephalopod ammonites, new species of sea urchins, lilies, etc. appear.

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

In the Cretaceous period, intense mountain building occurred, which was called the Laramie phase of Mesozoic folding. WITH greatest strength The Laramie orogeny developed at the boundary of the Lower and Upper Cretaceous, when extensive geosynclines arose in the Pacific mountainous countries. In the Mediterranean belt, this phase was preliminary and preceded the main orogenesis, 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 fractures of the Gondwana continent, the submergence of large areas of land and the formation of the Indian Ocean and South Atlantic depressions. Fractures of the earth's crust and mountain building were accompanied by the manifestation of volcanism.

The fauna of the Cretaceous period was dominated by reptiles and many species of birds appeared. There are still a few mammals. The sea continues to be dominated by ammonites and elasmobranch mollusks, sea urchins, lilies, corals, and foraminifera are widely developed, from the shells of which (partially) the formation of layers of white writing chalk occurred. The flora of the Lower Cretaceous is of a typical Mesozoic character. In it, gymnosperms continued to predominate, but in the Upper Cretaceous era, the dominant role passed to angiosperms, close to modern ones.

On the territory of 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, which 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 the closure of geosynclines 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 collapse of the ancient continental mass of Gondwana. Volcanic activity was no less intense in the Mesozoic than in the Paleozoic. Great changes have occurred in the composition of flora and fauna. Among terrestrial animals, reptiles flourished and declined at the end of the Cretaceous period. Ammonites, belemnites and a number of other animals underwent the same development in the seas. In place of the gymnosperms that dominated the Mesozoic, an angiosperm flora appeared in the second half of the Cretaceous.

Of the mineral resources formed in the Mesozoic era, the most important are oil, gas, coal, phosphorites and various ores.