The Mesozoic era is divided into the Triassic, Jurassic and Cretaceous s with a total duration of 173 million years. The deposits of these periods constitute the corresponding systems, which together form the Mesozoic group. The Triassic system is distinguished in Germany, the Jurassic and Cretaceous - in Switzerland and France. The Triassic and Jurassic systems are divided into three divisions, the Cretaceous - into two.

organic world

The organic world of the Mesozoic era is very different from the Paleozoic. The Paleozoic groups that died out in Perm were replaced by new Mesozoic ones.

In the Mesozoic seas received exceptional development cephalopods- ammonites and belemnites, the diversity and number of bivalve and gastropod molluscs increased sharply, six-ray corals appeared and developed. Of the vertebrates, bony fish and swimming reptiles are widespread.

Extremely diverse reptiles (especially dinosaurs) dominated on land. Gymnosperms flourished among terrestrial plants.

The organic world of the Triassicperiod. A feature of the organic world of this period was the existence of some archaic Paleozoic groups, although the new ones, the Mesozoic, predominated.

The organic world of the sea. Among the invertebrates, cephalopods and bivalves. Among the cephalopods, the ceratites dominated, which replaced the goniatites. The characteristic genus was ceratites with a typical ceratite septal line. The first belemnites appeared, but there were still few of them in the Triassic.

Bivalve mollusks inhabited shallow areas rich in food, where brachiopods lived in the Paleozoic. Bivalves rapidly developed, becoming more diverse in composition. The number of gastropods has increased, six-pointed corals and new sea urchins with a strong shell have appeared.

Marine vertebrates continued to evolve. Among the fish, the number of cartilaginous has decreased, and lobe-finned and lungfish have become rare. They were replaced by bony fish. The first turtles, crocodiles and ichthyosaurs lived in the seas - large swimming lizards, similar to dolphins.

The organic world of sushi has also changed. Stegocephals died out, and reptiles became the dominant group. The endangered cotilosaurs and animal-like lizards were replaced by Mesozoic dinosaurs, which were especially widespread in the Jurassic and Cretaceous. At the end of the Triassic, the first mammals appeared, they were small in size and primitive in structure.

The flora at the beginning of the Triassic was severely depleted due to the influence of the arid climate. In the second half of the Triassic, the climate became humid, and various Mesozoic ferns and gymnosperms (cycads, ginkgos, etc.) appeared. Along with them, conifers were widespread. By the end of the Triassic, the flora acquired a Mesozoic appearance, characterized by the predominance of gymnosperms.

organic world jurassic

The Jurassic organic world was most typical of the Mesozoic era.

The organic world of the sea. Among the invertebrates, ammonites dominated; they had a complex septal line and were extremely diverse in the shape of the shell and its sculpture. One of the typical Late Jurassic ammonites is the genus Virgatites, with its characteristic tufts of ribs on the shell. There are many belemnites, their rostra are found in mass quantities in Jurassic clays. Characteristic genera are cylindrotheuthis with a long cylindrical rostrum and hyobolites with a fusiform rostrum.

Bivalves and gastropods have become numerous and diverse. Among the bivalves there were many oysters with thick shells of various shapes. Various six-pointed corals, sea urchins and numerous protozoa lived in the seas.

Among marine vertebrates, fish lizards - ichthyosaurs - continued to dominate, scaly lizards - mesosaurs, similar to giant toothed lizards, appeared. The bony fish developed rapidly.

The organic world of sushi was very peculiar. Giant lizards - dinosaurs - of various shapes and sizes reigned supreme. At first glance, they seem to be aliens from the extraterrestrial world or a figment of the imagination of artists.

The Gobi desert and neighboring areas are richest in dinosaur remains. Central Asia. This vast territory for 150 million years before the Jurassic was in continental conditions favorable for long-term development fossil fauna. It is believed that this area was the center of the origin of dinosaurs, from where they settled all over the world up to Australia, Africa, and America.

Dinosaurs were gigantic. Modern elephants - the largest land animals today (up to 3.5 m tall and weighing up to 4.5 tons) - seem like dwarfs compared to dinosaurs. The largest were herbivorous dinosaurs. "Living mountains" - brachiosaurs, brontosaurs and diplodocus - had a length of up to 30 m and reached 40-50 tons. Huge stegosaurs carried large (up to 1 m) bone plates on their backs that protected their massive body. Stegosaurs had sharp spikes at the end of their tails. Among the dinosaurs there were many terrible predators that moved much faster than their herbivorous relatives. Dinosaurs reproduced using eggs, burying them in hot sand, as modern turtles do. In Mongolia, ancient dinosaur egg clutches are still being found.

Air environment mastered flying lizards - pterosaurs with sharp membranous wings. Rhamphorhynchus stood out among them - toothy lizards that ate fish and insects. At the end of the Jura, the first birds appeared - Archeopteryx - the size of a jackdaw, they retained many features of their ancestors - reptiles.

The flora of the land was distinguished by the flourishing of various gymnosperms: cycads, ginkgos, conifers, etc. The Jurassic flora was quite homogeneous on the globe, and only at the end of the Jura did floristic provinces begin to emerge.

Cretaceous Organic World

During this period, the organic world has undergone significant changes. At the beginning of the period, it was similar to the Jurassic, and in the Late Cretaceous it began to decline sharply due to the extinction of many Mesozoic groups of animals and plants.

organic world of the sea. Among the invertebrates, the same groups of organisms were common as in the Jurassic, but their composition changed.

Ammonites continued to dominate, among them many forms with partially or almost completely expanded shells appeared. Cretaceous ammonites are known with spiral-conical (like snails) and stick-like shells. At the end of the period, all ammonites became extinct.

The Belemnites reached their peak, they were numerous and varied. The genus Belemnitella with a cigar-like rostrum was especially widespread. The importance of bivalves and gastropods increased, they gradually seized the dominant position. Among bivalves there were many oysters, inoceramus and pectenes. Peculiar goblet-shaped hippurites lived in the tropical seas of the Late Cretaceous. In the shape of their shells, they resemble sponges and solitary corals. This is evidence that these bivalve mollusks led an attached lifestyle, unlike their relatives. Gastropod molluscs reached a great diversity, especially towards the end of the period. Among sea ​​urchins various wrong hedgehogs, one of the representatives of which is the genus Micraster with a heart-shaped shell.

The warm-water Late Cretaceous seas were overflowing with microfauna, among which small foraminifera-globigerins and ultramicroscopic unicellular calcareous algae - coccolithophorids predominated. The accumulation of coccoliths formed a thin calcareous silt, from which writing chalk was later formed. The softest varieties of writing chalk almost entirely consist of coccoliths, with an insignificant admixture of foraminifers.

There were many vertebrates in the seas. Bony fish developed rapidly, and they conquered marine environment. Until the end of the period, there were floating pangolins - ichthyosaurs, mososaurs.

The organic land world in the Early Cretaceous differed little from the Jurassic. The air was dominated by flying lizards - pterodactyls, similar to giant bats. Their wingspan reached 7-8 m, and in the USA the skeleton of a giant pterodactyl with a wingspan of 16 m was discovered. Along with such huge flying lizards, pterodactyls no larger than a sparrow lived. On land, various dinosaurs continued to dominate, but at the end of the Cretaceous they all died out along with their marine relatives.

The terrestrial flora of the Early Cretaceous, as in the Jurassic, was characterized by the predominance of gymnosperms, but starting from the end of the Early Cretaceous, angiosperms appear and rapidly develop, which, together with conifers, become the dominant group of plants by the end of the Cretaceous. Gymnosperms are drastically reduced in number and diversity, many of them are dying out.

Thus, at the end of the Mesozoic era, there were significant changes in both the animal and plant worlds. All ammonites disappeared, most belemnites and brachiopods, all dinosaurs, winged pangolins, many aquatic reptiles, ancient birds, a number of groups higher plants from gymnosperms.

Among these significant changes, the rapid disappearance from the face of the Earth of the Mesozoic giants - dinosaurs - is especially striking. What was the cause of the death of such a large and diverse group of animals? This topic has long attracted scientists and still does not leave the pages of books and scientific journals. There are several dozen hypotheses, and new ones are emerging. One group of hypotheses is based on tectonic causes - a strong orogeny caused significant changes in paleogeography, climate and food resources. Other hypotheses link the death of dinosaurs with processes that took place in space, mainly with changes in cosmic radiation. The third group of hypotheses explains the death of giants by various biological reasons: a discrepancy between the brain volume and body weight of animals; rapid development predatory mammals that ate small dinosaurs and large eggs; gradual thickening of the egg shell to such an extent that the cubs could not break through it. There are hypotheses linking the death of dinosaurs with an increase in trace elements in the environment, with oxygen starvation, with lime washed out of the soil, or with an increase in gravity on Earth to such an extent that giant dinosaurs were crushed by their own weight.

Mesozoic era

Mesozoic(Mesozoic era, from Greek μεσο- - “middle” and ζωον - “animal”, “living creature”) - a period of time in the geological history of the Earth from 251 million to 65 million years ago, one of the three eras of the Phanerozoic. First isolated in 1841 by British geologist John Phillips.

Mesozoic - an era of tectonic, climatic and evolutionary activity. There is a formation of the main contours of modern continents and mountain building on the periphery of the Pacific, Atlantic and Indian oceans; the division of the landmass contributed to speciation and other important evolutionary events. The climate was exceptionally warm throughout the entire time period, which also played a role important role in the evolution and formation of new animal species. By the end of the era, the main part of the species diversity of life approached its modern state.

Geological periods

Following the Paleozoic era, the Mesozoic stretches in time for about 180 million years: from 251 million years ago to the beginning of the Cenozoic era, 65 million years ago. This period is divided into three geological period, in the following order (beginning - end, million years ago):

  • Triassic period (251.0 - 199.6)
  • Jurassic (199.6 - 145.5)
  • Cretaceous (145.5 - 65.5)

The lower (between the Permian and Triassic periods, that is, between the Paleozoic and Mesozoic) boundary is marked by a massive Permian-Triassic extinction, as a result of which approximately 90-96% of marine fauna and 70% of land vertebrates died. Upper bound was established at the turn of the Cretaceous and Paleocene, when another very large extinction of many groups of plants and animals occurred, most often due to the fall of a giant asteroid (the Chicxulub crater on the Yucatan Peninsula) and the "asteroid winter" that followed. Approximately 50% of all species became extinct, including all dinosaurs.

Tectonics

Climate

Warm climate close to modern tropical

Flora and fauna

Scheme of the evolution of flora and fauna in the Mesozoic era.

Links

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  • Mesoamerican writing systems
  • Mesokaryotes

See what the "Mesozoic era" is in other dictionaries:

    MESOZOIC ERA- (secondary Mesozoic era) in geology, the period of the existence of the globe, corresponding to the deposits of the Triassic, Jurassic and Cretaceous; character. abundance and variety of reptiles, most of which have died out. Dictionary of foreign words included in ... ... Dictionary of foreign words of the Russian language

    MESOZOIC ERA- MESOZOIC ERATEM (ERA) (Mesozoic) (from Meso... (see MESO..., MEZ... (part compound words)) and Greek. zoe life), the second erathem (see ERATEM) (group) of the Phanerozoic eon (see PHANEROZOIC EON) and the era corresponding to it (see ERA (in geology)) ... ... encyclopedic Dictionary

    MESOZOIC ERA- the second after the Precambrian era of geol. the history of the Earth with a duration of 160 170 million years. It is divided into 3 periods: Triassic, Jurassic and Cretaceous. Geological dictionary: in 2 volumes. M.: Nedra. Edited by K. N. Paffengolts et al. 1978 ... Geological Encyclopedia

    mesozoic era- Mesozoic Mesozoic (about the period) (geol.) Topics Oil and gas industry Synonyms MesozoicMesozoic (about the period) EN Mesozoic ...

    Mesozoic era- this is the name in geology of a very significant period in the history of the development of the Earth, following the Paleozoic era and preceding the Cenozoic era, to which geologists also attribute the period we are experiencing. Deposits of the M. era constitute the M. group of layers ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

    mesozoic era- (Mesozoic), middle era Phanerozoic. Includes Triassic, Jurassic and Cretaceous periods. Lasted approx. 185 million years. It began 248 million years ago and ended 65 million years ago. In the Mesozoic, the single huge continents of Gondwana and Laurasia began to split into ... Biological encyclopedic dictionary

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    Mesozoic era- (Mesozoic) Mesozoic, Mesozoic, geological era between Paleozoic and Cenozoic eras, includes the Triassic, Jurassic and Cretaceous periods, lasted from approximately 248 to 65 million years ago. It was a time of abundance of vegetation and the predominance of ... ... Countries of the world. Dictionary

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    mesozoic era- The era that replaced the Paleozoic in the course of the history of the Earth's development; began 248 million years ago and preceded the Cenozoic era. It is divided into three periods: Triassic, Jurassic and Cretaceous. [Glossary of geological terms and concepts. Tomsk ... ... Technical Translator's Handbook

Books

  • Dinosaurs. The Complete Encyclopedia, Tamara Green. Dinosaurs are interesting to readers of absolutely all ages. This is also a favorite children's theme, which is confirmed by numerous cartoons and, of course, the classic film `Park ...

The Mesozoic era is 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. Large lakes and seas form inside the continents.

Characteristics of the Mesozoic era

At the end 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 tree ferns appear. angiosperms.

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. Flower plants, the appearance of the first predecessors of modern conifers, played an indispensable role in the development of modern life.

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Mesozoic era(248-65 million years ago) - the fourth epoch in evolutionary process the life of our planet. Its duration is 183 million years. The Mesozoic era is divided into 3 periods: Triassic, Jurassic and Cretaceous.

Periods of the Mesozoic Era

Triassic period (Triassic). The initial erathem of the Mesozoic era lasts 35 million years. This is the time of the formation of the Atlantic Ocean. The united continent of Pangea again begins to break into two parts - Gondwana and Laurasia. Inland continental water bodies begin to dry up actively. The depressions remaining from them are gradually filled with rock deposits. New mountain heights and volcanoes appear, which show increased activity. A huge part of the land is also occupied by desert zones with weather conditions unsuitable for the life of most species of living beings. Salt levels in water bodies are rising. During this time period, representatives of birds, mammals and dinosaurs appear on the planet.

Jurassic period (Jura)- the most famous period of the Mesozoic era. It got its name thanks to the sedimentary deposits of that time found in the Jura (mountains of Europe). Middle period The Mesozoic era lasts about 69 million years. The formation of modern continents begins - Africa, America, Antarctica, Australia. But they are not yet in the order to which we are accustomed. Deep bays and small seas appear, separating the continents. Continues active education mountain ranges. The Arctic Sea floods the north of Laurasia. As a result, the climate is humidified, and vegetation forms on the site of deserts.

Cretaceous (Cretaceous). The final period of the Mesozoic era takes a time interval of 79 million years. Angiosperms appear. As a result of this, the evolution of representatives of the fauna begins. The movement of the continents continues - Africa, America, India and Australia are moving away from each other. The continents of Laurasia and Gondwana begin to disintegrate into continental blocks. Huge islands are formed in the south of the planet. Expanding Atlantic Ocean. The Cretaceous period is the heyday of flora and fauna on land. In connection with the evolution flora, fewer minerals enter the seas and oceans. The number of algae and bacteria in water bodies is reduced.

In details periods of the mesozoic era will be considered in the following lectures.

The climate of the Mesozoic era

The climate of the Mesozoic era at the very beginning there was one on the whole planet. The air temperature at the equator and the poles was kept at the same level. At the end of the first period of the Mesozoic era, a drought reigned on Earth for most of the year, which was briefly replaced by rainy seasons. But, despite the arid conditions, the climate became much colder than it was during the Paleozoic period. Some species of reptiles have fully adapted to cold weather. Mammals and birds would later evolve from these animal species.

In the Cretaceous, it gets even colder. All continents have their own climate. Tree-like plants appear, which lose their foliage during the cold season. Snow begins to fall at the North Pole.

Plants of the Mesozoic Era

At the beginning of the Mesozoic, the continents were dominated by club mosses, various ferns, the ancestors of modern palms, conifers and ginkgo trees. In the seas and oceans, the dominance belonged to the algae that formed the reefs.

The increased humidity of the climate of the Jurassic period led to the rapid formation of the plant mass of the planet. The forests consisted of ferns, conifers and cycads. Tui and araucaria grew near water bodies. In the middle of the Mesozoic era, two belts of vegetation formed:

  1. Northern, dominated by herbaceous ferns and ginkgo trees;
  2. Southern. Tree ferns and cicadas reigned here.

In the modern world, ferns, cycads (palm trees reaching a size of 18 meters) and cordaites of that time can be found in tropical and subtropical forests. Horsetails, club mosses, cypresses and spruce trees practically did not have any differences from those that are common in our time.

The Cretaceous period is characterized by the appearance of plants with flowers. In this regard, butterflies and bees appeared among insects, thanks to which flowering plants could quickly spread across the planet. Also at this time, ginkgo trees begin to grow with foliage falling in the cold season. Coniferous forests of this time period are very similar to modern ones. They include yews, firs and cypresses.

The development of higher gymnosperms lasts throughout the Mesozoic era. These representatives of the terrestrial flora got their name due to the fact that their seeds did not have an outer protective shell. The most widespread are cycads and bennettites. In appearance, cycads resemble tree ferns or cycads. They have straight stems and massive feather-like leaves. Bennettites are trees or shrubs. Outwardly similar to cycads, but their seeds are covered with a shell. This brings plants closer to angiosperms.

In the Cretaceous, angiosperms appear. From this moment begins a new stage in the development of plant life. Angiosperms (flowering) are at the top rung of the evolutionary ladder. They have special bodies reproduction - stamens and pistil, which are in the flower bowl. Their seeds, unlike gymnosperms, hide a dense protective shell. These mesozoic era plants quickly adapt to any climatic conditions and are actively developing. Behind short term angiosperms began to dominate the entire Earth. Their various types and forms have reached modern world- eucalyptus, magnolias, quince, oleanders, walnut trees, oaks, birches, willows and beeches. Of the gymnosperms of the Mesozoic era, now we are only familiar with coniferous species - fir, pine, sequoia and some others. The evolution of plant life of that period significantly overtook the development of representatives of the animal world.

Animals of the Mesozoic Era

Animals in the Triassic period of the Mesozoic era actively evolved. A huge variety of more developed creatures was formed, which gradually replaced the ancient species.

One of these types of reptiles was pelycosaurs, similar to animals - sailing lizards. On their backs was a huge sail, similar to a fan. They were replaced by therapsids, which were divided into 2 groups - predators and herbivores. Their paws were powerful, their tails were short. In terms of speed and endurance, therapsids far surpassed pelycosaurs, but this did not save their species from extinction at the end of the Mesozoic era.

The evolutionary group of lizards, from which mammals would later emerge, are the cynodonts (dog teeth). These animals got their name due to powerful jaw bones and sharp teeth, with which they could easily chew raw meat. Their bodies were covered with thick fur. Females laid eggs, but newborn cubs fed on mother's milk.

At the beginning of the Mesozoic era, formed the new kind pangolins - archosaurs (ruling reptiles). They are the ancestors of all dinosaurs, pterosaurs, plesiosaurs, ichthyosaurs, placodonts, and crocodylomorphs. Archosaurs, adapted to the climatic conditions on the coast, became predatory thecodonts. They hunted on land near water bodies. Most thecodonts walked on 4 legs. But there were also individuals who ran on their hind legs. In this way, these animals developed incredible speed. Over time, thecodonts evolved into dinosaurs.

By the end Triassic period dominated by 2 species of reptiles. Some are the ancestors of the crocodiles of our time. Others have become dinosaurs.

Dinosaurs are not like other lizards in body structure. Their paws are located under the body. This feature allowed the dinosaurs to move quickly. Their skin is covered with waterproof scales. Lizards move on 2 or 4 legs, depending on the species. The first representatives were fast coelophyses, powerful herrerasaurs and huge plateosaurs.

In addition to dinosaurs, archosaurs gave rise to another type of reptile that is different from the rest. These are pterosaurs - the first pangolins that can fly. They lived near water bodies, and ate various insects for food.

The fauna of the sea depths of the Mesozoic era is also characterized by a variety of species - ammonites, bivalves, shark families, bony and ray-finned fish. The most outstanding predators were the underwater lizards that appeared not so long ago. Dolphin-like ichthyosaurs had high speed. One of the giant representatives of ichthyosaurs is Shonisaurus. Its length reached 23 meters, and its weight did not exceed 40 tons.

Lizard-like notosaurs had sharp fangs. Plakadonts, similar to modern newts, were searched on seabed shells of mollusks, which were bitten with teeth. Tanystrophei lived on land. Long (2-3 times the size of the body), slender necks allowed them to catch fish standing on the shore.

Another group of marine dinosaurs of the Triassic period are plesiosaurs. At the beginning of the era, plesiosaurs reached a size of only 2 meters, and by the middle of the Mesozoic evolved into giants.

The Jurassic period is the time of the development of dinosaurs. The evolution of plant life gave impetus to the emergence of different types of herbivorous dinosaurs. And this, in turn, led to an increase in the number of predatory individuals. Some types of dinosaurs were the size of a cat, while others were as large as giant whales. The most gigantic individuals are diplodocus and brachiosaurus, reaching a length of 30 meters. Their weight was about 50 tons.

Archeopteryx is the first creature to stand on the border between lizards and birds. Archeopteryx did not yet know how to fly long distances. Their beak was replaced by jaws with sharp teeth. The wings ended in fingers. Archeopteryx were the size of modern crows. They lived mainly in forests, and ate insects and various seeds.

In the middle of the Mesozoic era, pterosaurs are divided into 2 groups - pterodactyls and rhamphorhynchus. Pterodactyls lacked a tail and feathers. But there were large wings and a narrow skull with a few teeth. These creatures lived in flocks on the coast. During the day they hunted for food, and at night they hid in the trees. Pterodactyls ate fish, shellfish and insects. To take to the skies, this group of pterosaurs had to jump from high places. Ramphorhynchus also lived on the coast. They ate fish and insects. They had long tails with a blade at the end, narrow wings and a massive skull with teeth. different sizes, which was convenient to catch slippery fish.

by the most dangerous predator sea ​​depths was Liopleurodon, weighing 25 tons. Huge Coral reefs, in which ammonites, belemnites, sponges and sea mats settled. Representatives of the shark family develop and bony fish. New species of plesiosaurs and ichthyosaurs, sea turtles and crocodiles appeared. Saltwater crocodiles have flippers instead of legs. This feature allowed them to increase their speed in the aquatic environment.

During the Cretaceous period of the Mesozoic era there were bees and butterflies. Insects carried pollen, and flowers gave them food. Thus began a long-term cooperation between insects and plants.

The most famous dinosaurs of that time were predatory tyrannosaurs and tarbosaurs, herbivorous bipedal iguanodons, quadrupedal rhinoceros-like Triceratops and small armored ankylosaurs.

Most of the mammals of that period belong to the subclass Allotherium. These are small animals, similar to mice, weighing no more than 0.5 kg. The only exceptional species is repenomamas. They grew up to 1 meter and weighed 14 kg. At the end of the Mesozoic era, the evolution of mammals takes place - the ancestors of modern animals are separated from allotheria. They were divided into 3 types - oviparous, marsupial and placental. It is they who at the beginning of the next era replace the dinosaurs. From the placental species of mammals, rodents and primates appeared. Purgatorius became the first primates. From the marsupial species, modern opossums originated, and the egg-laying species gave rise to platypuses.

The air space is dominated by early pterodactyls and new types of flying reptiles - orcheopteryx and quetzatcoatl. These were the most gigantic flying creatures in the entire history of the development of our planet. Together with representatives of pterosaurs, birds dominate the air. Many ancestors appeared in the Cretaceous period modern birds- ducks, geese, loons. The length of the birds was 4-150 cm, weight - from 20 g. up to several kilograms.

Huge predators reigned in the seas, reaching a length of 20 meters - ichthyosaurs, plesiosaurs and mososaurs. Plesiosaurs had very long necks and small heads. Their large size did not allow them to develop great speed. The animals ate fish and shellfish. Mososaurs replaced saltwater crocodiles. These are giant predatory lizards with an aggressive character.

At the end of the Mesozoic era, snakes and lizards appeared, the species of which have reached the modern world without changing. Turtles of this time period also did not differ from those that we see now. Their weight reached 2 tons, length - from 20 cm to 4 meters.

By the end of the Cretaceous period, most reptiles begin to die out en masse.

Minerals of the Mesozoic era

associated with the Mesozoic era a large number of deposits natural resources. These are sulfur, phosphorites, polymetals, building and combustible materials, oil and natural gas.

On the territory of Asia, in connection with active volcanic processes, the Pacific belt was formed, which gave the world large deposits of gold, lead, zinc, tin, arsenic and other types of rare metals. In terms of coal reserves, the Mesozoic era is significantly inferior to Paleozoic era, but even during this period several large deposits brown and hard coal - Kansky basin, Bureinsky, Lensky.

Mesozoic oil and gas fields are located in the Urals, Siberia, Yakutia, Sahara. Phosphorite deposits have been found in the Volga and Moscow regions.

Lesson topic:"The Development of Life in the Mesozoic Era"

The duration of the Mesozoic era is approximately 160 million years. The Mesozoic era includes the Triassic (235-185 million years ago), Jurassic (185-135 million years) and Cretaceous (135-65 million years ago) periods. The development of organic life on Earth and the evolution of the biosphere continued against the background of paleogeographical changes characteristic of this stage.

The Triassic is characterized by a general uplift of platforms and an increase in land area.

By the end of the Triassic, the destruction of most mountain systems that emerged in the Paleozoic. The continents turned into huge plains, which in the next, Jurassic, period, the ocean began to advance. The climate became milder and warmer, capturing not only the tropical and subtropical zones, but also modern temperate latitudes. During the Jurassic, the climate is warm and humid. The increased rainfall caused the formation of seas, huge lakes and large rivers. The change in physical and geographical conditions affected the development of the organic world. The extinction of representatives of the marine and terrestrial biota continued, which began in the arid Permian, which was called the Permian-Triassic crisis. After this crisis, and as a result of it, the flora and fauna of the land evolved.

In biological terms, the Mesozoic was a time of transition from old, primitive to new, progressive forms. The Mesozoic world was much more diverse than the Paleozoic, fauna and flora appeared in it in a significantly updated composition.

Flora

The vegetation cover of the land at the beginning of the Triassic period was dominated by ancient coniferous and seed ferns (pteridosperms). in arid climates, these gymnosperms gravitated to moist places. On the coasts of drying reservoirs and in disappearing swamps, the last representatives of ancient club mosses, some groups of ferns, perished. By the end of the Triassic, a flora was formed in which ferns, cycads, and ginkgoes dominated. Gymnosperms flourished during this period.

In the Cretaceous, flowering plants appeared and conquered the land.

The supposed ancestor of flowering plants, according to most scientists, was closely related to seed ferns and represented one of the branches of this group of plants. Paleontological remains of primary flowering plants and a group of plants intermediate between them and gymnosperm ancestors, unfortunately, are still unknown to science.

primary type flowering plant was, according to most botanists, an evergreen tree or low shrub. The herbaceous type of flowering plant appeared later under the influence of limiting environmental factors. The idea of ​​the secondary nature of the herbaceous type of angiosperms was first expressed in 1899 by the Russian botanical geographer A.N. Krasnov and the American anatomist C. Jeffrey.

The evolutionary transformation of woody forms into herbaceous ones occurred as a result of a weakening, and then a complete or almost complete decrease in the activity of the cambium. Such a transformation probably began at the dawn of the development of flowering plants. With the passage of time, it proceeded more rapidly in the most distant groups of flowering plants and eventually acquired such a wide scale that it covered all the main lines of their development.

Of great importance in the evolution of flowering plants was neoteny - the ability to reproduce on early stage ontogeny. It is usually associated with limiting environmental factors - low temperature, lack of moisture and a short growing season.

Of the huge variety of woody and herbaceous forms, flowering plants turned out to be the only group of plants capable of forming complex multi-tiered communities. The emergence of these communities led to a more complete and intensive use of the natural environment, the successful conquest of new territories, especially unsuitable for gymnosperms.

In the evolution and mass dispersal of flowering plants, the role of pollinating animals is also great, especially insects. Feeding on pollen, insects carried it from one strobilus of the original angiosperm ancestors to another and, thus, were the first agents of cross-pollination. Over time, insects adapted to eat the ovules, already causing significant damage to plant reproduction. The reaction to such a negative influence of insects was the selection of adaptive forms with closed ovules.

The conquest of land by flowering plants marks one of the decisive, turning points in the evolution of animals. This parallelism between the suddenness and rapidity of the spread of angiosperms and mammals is explained by interdependent processes. The conditions associated with the flowering of angiosperms were also favorable for mammals.

Fauna

Fauna of the seas and oceans: Mesozoic invertebrates were already approaching modern ones in character. A prominent place among them was occupied by cephalopods, to which modern squids and octopuses belong. The Mesozoic representatives of this group included ammonites with a shell twisted into a “ram's horn”, and belemnites, the inner shell of which was cigar-shaped and overgrown with the flesh of the body - the mantle. Ammonites were found in the Mesozoic in such quantities that their shells are found in almost all marine sediments of this time.

By the end of the Triassic, most of the ancient groups of ammonites die out, but in the Cretaceous period they are still numerous., but during the Late Cretaceous, the number of species in both groups begins to decline. The diameter of the shells of some ammonites reaches 2.5 m.

At the end of the Mesozoic, all ammonites became extinct. From cephalopods external sink only the genus Nautilus has survived to this day. Forms with an internal shell are more widely distributed in modern seas - octopuses, cuttlefish and squids, remotely related to belemnites.

Six-pointed corals began to actively develop(Hexacoralla), whose colonies were active reef-formers. Mesozoic echinoderms were represented by various types of crinoids, or crinoids (Crinoidea), which flourished in the shallow waters of the Jurassic and partly Cretaceous seas. However sea ​​urchins have made the most progress. Starfish were plentiful.

Bivalve molluscs also spread strongly.

During the Jurassic, the foraminifera flourished again that survived the Cretaceous period and reached modern times. In general, unicellular protozoa were an important component in the formation of Mesozoic sedimentary rocks. The Cretaceous period was also a time of rapid development of new types of sponges and some arthropods, in particular insects and decapods.

The Mesozoic era was a time of unstoppable expansion of vertebrates. Of the Paleozoic fish, only a few moved into the Mesozoic.. Among them were freshwater sharks, marine sharks continued to evolve throughout the Mesozoic; most modern genera were already represented in the seas of the Cretaceous, in particular.

Almost all lobe-finned fish, from which the first terrestrial vertebrates developed, died out in the Mesozoic. Paleontologists believed that the crossopterans 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 fish species 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 crossopterans ( Coelacanthida). Until now this view remains the only modern representative of the ancient lobe-finned fish. He got the name Latimeria chalumnae. Such biological phenomena are referred to as "living fossils".

Sushi fauna: New groups of insects appeared on land, the first dinosaurs and primitive mammals. The most widespread in the Mesozoic were reptiles, which became truly the dominant class of this era.

With the advent of dinosaurs early reptiles became completely extinct in the middle of the Triassic cotylosaurs and mammals, as well as the last large amphibian stegocephals. Dinosaurs, which were the most numerous and diverse superorder of reptiles, have become the leading Mesozoic group of terrestrial vertebrates since the end of the Triassic. For this reason, the Mesozoic is called the era of the dinosaurs. In the Jurassic, among the dinosaurs one could meet real monsters, up to 25-30 m long (with a tail) and weighing up to 50 tons. Of these giants, such forms as the brontosaurus (Brontosaurus), diplodocus (Diplodocus) and brachiosaurus (Brachiosaurus) are best known.

The original ancestors of the dinosaurs may have been the Upper Permian eosuchia, a primitive detachment of small reptiles with a physique resembling a lizard. From them, in all likelihood, a large branch of reptiles arose - archosaurs, which then broke up into three main branches - dinosaurs, crocodiles and winged pangolins. The archosaurs were thecodonts. Some of them lived in the water and outwardly resembled crocodiles. Others, like large lizards, lived in open areas of land. These terrestrial thecodonts adapted to bipedal walking, which provided them with the ability to observe in search of prey. It was from such thecodonts, which became extinct at the end of the Triassic, that dinosaurs originated, inheriting a bipedal mode of movement, although some of them switched to a quadrupedal mode of movement. Representatives of the climbing forms of these animals, which eventually switched from jumping to gliding flights, gave rise to pterosaurs (pterodactyls) and birds. Dinosaurs included both herbivores and carnivores.

By the end of the Cretaceous, the mass extinction of characteristic Mesozoic groups of reptiles, including dinosaurs, ichthyosaurs, plesiosaurs, pterosaurs and mosasaurs, occurs.

Members of the bird class (Aves) first appear in Jurassic deposits. The only known first bird was Archeopteryx. The remains of this first bird were found near the Bavarian city of Solnhofen (Germany). During the Cretaceous, bird evolution proceeded at a rapid pace; characteristic of this time, still possessing serrated jaws. The emergence of birds was accompanied by a number of aromorphoses: they acquired a hollow septum between the right and left ventricles of the heart, lost one of the aortic arches. The complete separation of arterial and venous blood flows determines the warm-bloodedness of birds. Everything else, namely, feather cover, wings, horny beak, air sacs and double breathing, as well as shortening of the hindgut, are idioadaptations.

First mammals (Mammalia), modest animals, not exceeding the size of 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 had largely died out. Their occurrence is associated with a number of major aromorphoses, developed in representatives of one of the subclasses of reptiles. These aromorphoses include: the formation of a hairline and a 4-chambered heart, complete separation of arterial and venous blood flow, intrauterine development of offspring and feeding the baby with milk. Aromorphoses include development of the cerebral cortex, causing the predominance of conditioned reflexes over unconditioned ones and the possibility of adapting to changing environmental conditions by changing behavior.

Almost all Mesozoic groups of the animal and plant kingdoms 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 to development and, in the end, living species of organisms are formed.