The development of life in the Mesozoic era. Mesozoic era. Other reptiles of the Mesozoic era

Age of reptiles

In the mass consciousness, the Mesozoic era has long been rooted as the era of the dinosaurs, which reigned supreme over the planet for a little less than two hundred million years. This is partly true. But this is not the only remarkable thing about this historical period from a geological and biological point of view. The Mesozoic era, the periods of which (Triassic, Cretaceous and Jurassic) have their own characteristic features, is a temporal subdivision of the geochronological scale, which lasted about one hundred and sixty million years.

General characteristics of the Mesozoic

During this huge time span, which started about 248 million years ago and ended 65 million years ago, the last supercontinent Pangea disintegrated. And the Atlantic Ocean was born. During this period, chalk deposits on the ocean floor were formed by unicellular algae and protozoa. Getting into the zones of collision of lithospheric plates, these carbonate sediments contributed to the increased emission of carbon dioxide during volcanic eruptions, which significantly changed the composition of the water and the atmosphere. Land life in the Mesozoic era was characterized by the dominance of giant dinosaurs and gymnosperms. In the second half of the Cretaceous period, mammals, familiar to us today, began to enter the evolutionary scene, which were then hindered by dinosaurs to fully develop. Significant temperature drops associated with the introduction of angiosperms into the terrestrial ecosystem and new classes of unicellular algae into the marine environment have disrupted the structure of biological communities. The Mesozoic era is also characterized by a significant restructuring of food webs that began towards the middle of the Cretaceous.

Triassic. Geology, sea creatures, plants

The Mesozoic era began with the Triassic period, which replaced the Permian geological era. Living conditions during this period practically did not differ from those in Perm. There were no birds and grass on Earth at that time. Some part of the modern North American continent and Siberia was at that time the seabed, and the territory of the Alps was hidden under the waters of the Tethys - a giant prehistoric ocean. Due to the lack of corals, green algae were engaged in the construction of reefs, neither before, nor after did not play the first roles in this process. Also, a characteristic feature of life in the Triassic was the combination of old biological species with new ones that had not yet gained strength. The time of conodonts and cephalopods with straight shells was coming to an end; some six-rayed coral species have already begun to emerge and are yet to flourish; the first bony fishes and sea urchins were formed, which have a solid shell that does not decompose after death. Among terrestrial species, lepidodendrons, cordaites and treelike horsetails survived their long centuries. They were replaced by the well-known conifers to all of us.

Fauna of the Triassic

Among animals, amphibians began to appear - the first stegocephals, but dinosaurs, including their flying species, began to spread more and more widely. At first, these were small creatures, similar to modern lizards, equipped with various biological adaptations for takeoff. Some had dorsal growths that resemble wings. They could not swing, but they managed to descend successfully with their help, like parachutists. Others were equipped with membranes that allowed them to glide. Such prehistoric hang-gliders. And glovipteryx had a full arsenal of such flight membranes. Its wings can be considered the hind limbs, the length of which significantly exceeded the linear dimensions of the rest of the body. During this period, small mammals, hiding in burrows from the hosts of the planet, were already hiding, waiting for their hour. Their time will come yet. This is how the Mesozoic era began.

Jurassic period

This era has gained immense fame thanks to one Hollywood film in which fiction is more than authentic. The truth is only in one thing - this is the flourishing of the power of dinosaurs, which simply suppressed other forms of animal life. In addition, the Jurassic period is notable for the complete disintegration of Pangea into separate continental blocks, which significantly changed the geography of the planet. The population of the ocean floor has undergone extremely strong changes. Brachiopods were supplanted by bivalve molluscs, and primitive shells by oyster. Nowadays, it is difficult to imagine the wealth and splendor of the Jurassic forests, especially on the humid coasts. These are giant trees and fantastic ferns, extremely lush shrub vegetation. And, of course, a huge variety of dinosaurs - the largest creatures that have ever lived on the planet.

The last dinosaur ball

The largest events of this era in the plant world took place in the middle of the Cretaceous period. The first flowers bloomed, therefore, angiosperms appeared, which still dominate the flora of the planet. Real thickets of laurels, willows, poplars, plane trees and magnolias have already appeared. In principle, the flora at that distant time acquired an almost modern shape, which cannot be said about animals. It was the world of ceratopsians, ankylosaurs, tyrannosaurs and the like. It all ended in a tremendous catastrophe - the largest in earthly history. And the era of mammals has come. That over time made it possible for a person to come to the fore, but that's another story.

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, reptiles began to flourish, which were adapted to drought (Fig. 44). Among the plants in the Triassic, strong development was achieved gymnosperms.

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

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

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

From reptiles, the vestige 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 animal-toothed lizards. But tricodonts the size of a rat could not compete with reptiles, so they did not spread widely.

Yura named for a French city located on the border with Switzerland. In this period, dinosaurs "conquer" the planet. They have mastered not only land, water, but also air. There are currently 250 known species of dinosaurs. One of the most characteristic 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 a neck.

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

The rather mild climate favored the development of angiosperms.

chalk- the name was given because of the powerful chalk deposits formed from the remains of the shells of small marine animals. In this period, angiosperms appear and spread extremely rapidly, and gymnosperms are displaced.

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

At the end of the Cretaceous, the climate became colder, the vegetation of the coastal lowlands died. Herbivorous, carnivorous dinosaurs died along with the vegetation. Large reptiles (crocodile) survived only in the tropical zone.

In the conditions of a sharply continental climate and a general cold snap, warm-blooded 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, the evolution of reptiles developed in six directions:

1st direction - turtles (appeared in the Permian period, have a complex shell, fused with ribs and chest 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). The appearance is similar to that of a fish and a whale, short neck, fins, swim with the help of a tail, legs control movement. Intrauterine development - viviparity of offspring.

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

Aromorphoses that contributed to the emergence of mammals.

1. The complication of the nervous system, the development of the cerebral cortex influenced the change in the behavior of animals, adaptation to the living environment.

2. The spine is divided into vertebrae, the limbs are located from the abdominal part closer to the back.

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

4. Hair has appeared to preserve body heat.

5. There was a division into a large and a small circle of blood circulation, warm-bloodedness appeared.

6. Lungs with numerous bubbles, enhancing gas exchange, have developed.

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 Dinosaur period?

2. Understand the aromorphosis that causes mammals to appear.

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 in the Cretaceous.

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

1. Angiosperms.

2. Tricodonts.

4. Eucalyptus.

5. Archeopteryx.

6. Turtles.

7. Butterflies.

8. Brachiosaurus.

9. Tuatara.

11. Dinosaurs.

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

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general information

The Mesozoic era lasted for about 160 million BC.

years. It is customary to subdivide it into three periods: Triassic, Jurassic and Cretaceous; the first two periods were much shorter than the third, lasting 71 million.

Biologically, the Mesozoic was a time of transition from old, primitive to new, progressive forms. Neither four-pointed corals (rugoses), nor trilobites, nor graptolites crossed the invisible border that lay between the Paleozoic and Mesozoic.

The Mesozoic world was much more diverse than the Paleozoic, the fauna and flora appeared in it in a significantly renewed composition.

2. Triassic period

Periodization: from 248 to 213 million years ago.

The Triassic period in the history of the Earth marked the beginning of the Mesozoic era, or the era of "middle life". Before him, all the continents were merged into a single giant supercontinent Panagea. With the onset of the Triassic, Pangea again began to split into Gondwana and Laurasia, and the Atlantic Ocean began to form.

Sea levels all over the world were very low. The climate, almost everywhere warm, gradually became drier, and vast deserts formed in the inland regions. Shallow seas and lakes evaporated intensively, which is why the water in them became very salty.

Animal world.

Dinosaurs and other reptiles have become the dominant group of land animals. The first frogs appeared, and a little later land and sea turtles and crocodiles. The first mammals also appeared, and the variety of mollusks increased.

New species of coral, shrimp and lobster have developed. By the end of the period, almost all ammonites had died out. Marine reptiles such as ichthyosaurs have taken root in the oceans, and pterosaurs have begun to explore the air.

The largest aromorphoses: the appearance of a four-chambered heart, complete separation of arterial and venous blood, warm-bloodedness, mammary glands.

Vegetable world.

Below, there was a carpet of ploons and horsetails, as well as palm-like bennettites.

Fauna and flora in the Mesozoic. Development of life during the Triassic, Jurassic and Cretaceous periods

Jurassic period

Periodization: from 213 to 144 million years ago.

By the beginning of the Jurassic period, the giant supercontinent Pangea was in the process of active decay. South of the equator, there was still a single vast continent, which was again called Gondwana. Later, it also split into parts that formed today's Australia, India, Africa and South America.

The sea flooded a significant part of the land. Intense mountain building took place. At the beginning of the period, the climate was generally warm and dry, then became more humid.

Terrestrial animals of the northern hemisphere could no longer freely move from one continent to another, but they continued to spread freely throughout the southern supercontinent.

Animal world.

The number and diversity of sea turtles and crocodiles increased, and new species of plesiosaurs and ichthyosaurs appeared.

Insects, the precursors of modern flies, wasps, earwigs, ants and bees, prevailed on land. The first Archeopteryx bird also appeared. Dinosaurs dominated, evolving into many forms, from giant sauropods to smaller, faster-footed predators.

Vegetable world.

The climate became more humid, and all the land was overgrown with abundant vegetation. The forerunners of the current cypresses, pines and mammoth trees appeared in the forests.

The largest aromorphoses were not identified.

Cretaceous period

Mesozoic Biological Triassic Jurassic

Periodization: from 144 to 65 million years ago.

During the Cretaceous period, the "great split" of the continents continued on our planet. The huge land masses that formed Laurasia and Gondwana were gradually falling apart. South America and Africa were moving away from each other, and the Atlantic Ocean became wider and wider. Africa, India and Australia also began to diverge in different directions, and as a result, giant islands were formed south of the equator.

Most of the territory of modern Europe was then under water.

The sea flooded vast tracts of land.

The remains of hard-cover planktonic organisms formed huge strata of chalk deposits on the ocean floor. At first, the climate was warm and humid, but then it became noticeably colder.

Animal world.

The number of belemnites increased in the seas.

The oceans were dominated by giant sea turtles and predatory marine reptiles. Snakes appeared on land, and new varieties of dinosaurs and insects such as moths and butterflies emerged. At the end of the period, another mass extinction led to the extinction of ammonites, ichthyosaurs and many other groups of marine animals, and all dinosaurs and pterosaurs died out on land.

The largest aromorphosis is the appearance of the uterus and intrauterine development of the fetus.

Vegetable world.

The first flowering plants appeared, establishing close "cooperation" with insects that carried their pollen.

They quickly spread throughout the land.

The largest aromorphosis is the formation of a flower and a fruit.

5. Results of the Mesozoic era

The Mesozoic era is the era of middle life. It is named so because the flora and fauna of this era are transitional between the Paleozoic and Cenozoic. In the Mesozoic era, the modern outlines of continents and oceans, modern marine fauna and flora are gradually formed.

The Andes and Cordillera, the mountain ranges of China and East Asia were formed. The troughs of the Atlantic and Indian oceans were formed. The formation of the troughs of the Pacific Ocean began. There have also been serious aromorphoses in the plant and animal worlds. Gymnosperms become the predominant department of plants, and in the animal world, the appearance of a four-chambered heart and the formation of a uterus are of the same importance.

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Mesozoic era

The beginning of the Mesozoic era as a transitional period in the development of the earth's crust and life.

Substantial restructuring of the structural plan of the Earth. Triassic, Jurassic and Cretaceous periods of the Mesozoic era, their description and characteristics (climate, flora and fauna).

presentation added on 05/02/2015

Cretaceous period

Geological structure of the planet in the Cretaceous. Tectonic changes during the Mesozoic stage of development.

The reasons for the extinction of dinosaurs. Cretaceous period as the last period of the Mesozoic era. Characteristics of vegetation and animals, their aromorphoses.

presentation added on 11/29/2011

Class Reptiles

Reptiles are a paraphyletic group of predominantly terrestrial vertebrates, including modern turtles, crocodiles, beakheads, amphisbens, lizards, chameleons and snakes.

General characteristics of the largest land animals, analysis of features.

presentation added on 05/21/2014

Features of the study of the fauna of terrestrial vertebrates in urbanized areas

Urban habitat for animals of any species, species composition of terrestrial vertebrates in the study area.

Classification of animals and features of their biological diversity, ecological problems of synanthropization and synurbanization of animals.

term paper, added 03/25/2012

Development of life in the Mesozoic era

Review of the features of the development of the earth's crust and life in the Triassic, Jurassic and Cretaceous periods of the Mesozoic era. Descriptions of Variscian mountain-building processes, the formation of volcanic regions.

Analysis of climatic conditions, representatives of fauna and flora.

presentation added on 10/09/2012

Development of life on Earth

Geochronological table of the development of life on Earth. Characteristics of the climate, tectonic processes, conditions for the emergence and development of life in the Archean, Proterozoic, Paleozoic and Mesozoic eras.

Tracking the process of complication of the organic world.

presentation added on 02/08/2011

Study history, classification of dinosaurs

Characterization of dinosaurs as a superorder of terrestrial vertebrates that lived in the prehistoric era.

Paleontological studies of the remains of these animals. Scientific classification of them into carnivorous and herbivorous subspecies.

History of the study of dinosaurs.

presentation added on 04/25/2016

Herbivorous dinosaurs

The study of the lifestyle of herbivorous dinosaurs, which include all ornithischian dinosaurs and sauropodomorphs - a suborder of lizard-like dinosaurs, which indicates how diverse they were, even in spite of the restrictions imposed by the way of feeding.

abstract, added 12/24/2011

Silurian period of the Paleozoic era

The Silurian period is the third geological period of the Paleozoic era.

The gradual sinking of land under water is a characteristic feature of the Silurian. Features of the animal world, the distribution of invertebrates. The first terrestrial plants were psilophytes (bare plants).

presentation added on 10/23/2013

Mesozoic era

Massive Permian extinction. The reasons for the extinction of dinosaurs and many other living organisms at the Cretaceous and Paleogene boundary. Beginning, middle and end of the Mesozoic. Fauna of the Mesozoic era.

Dinosaur, pterosaur, rhamphorhynchus, pterodactyl, tyrannosaurus, deinonychus.

presentation added on 05/11/2014

Mesozoic era

The Mesozoic era (252-66 million years ago) is the second era of the fourth eon - the Phanerozoic. Its duration is 186 million years. The main features of the Mesozoic: the modern outlines of continents and oceans, modern marine fauna and flora are gradually forming. The Andes and Cordillera, the mountain ranges of China and East Asia were formed. The troughs of the Atlantic and Indian oceans were formed. The formation of the troughs of the Pacific Ocean began.

Periods of the Mesozoic era

Triassic, Triassic, - the first period of the Mesozoic era, lasts 51 million years.

This is the time of the formation of the Atlantic Ocean. The single continent of Pangea again begins to break into two parts - Gondwana and Laurasia. Inland water bodies are beginning to dry up actively. The depressions left from them are gradually filled with rock deposits.

New mountain heights and volcanoes appear, which are showing increased activity. A huge part of the land is still occupied by desert zones with weather conditions unsuitable for the life of most species of living beings. Salt levels in water bodies are increasing. During this time period, representatives of birds, mammals and dinosaurs appear on the planet. Read more - Triassic period.

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 (mountain ranges of Europe). The middle period of the Mesozoic era lasts about 56 million years. The formation of modern continents begins - Africa, America, Antarctica, Australia. But they are not yet arranged in the order we are used to.

Deep bays and small seas appear, dividing the continents. The active formation of mountain ranges continues. The Arctic Sea floods the north of Laurasia. As a result, the climate is humidified, and vegetation forms in the place of deserts.

Cretaceous (Chalk)- the final period of the Mesozoic era, occupies a time interval of 79 million years. Angiosperms appear. As a result, the evolution of the fauna begins. Continents continue to move - Africa, America, India and Australia are moving away from each other. The continents of Laurasia and Gondwana are beginning to disintegrate into continental blocks. In the south of the planet, huge islands are being formed.

The Atlantic Ocean is expanding. The Cretaceous Period is the heyday of flora and fauna on land. Due to the evolution of the plant kingdom, fewer minerals enter the seas and oceans. The number of algae and bacteria in water bodies decreases. Read more - Cretaceous period

Mesozoic climate

The climate of the Mesozoic era at the very beginning was the same on the entire planet. The air temperature at the equator and poles was kept at the same level.

At the end of the first period of the Mesozoic era, most of the year, drought reigned on Earth, which was briefly replaced by rainy seasons. But, despite the arid conditions, the climate became much colder than it was during the Paleozoic.

Some reptile species have fully adapted to the cold weather. From these species of animals, mammals and birds would later arise.

It gets even colder in the Cretaceous. All continents have their own climate. Treelike 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 lyciferous, various ferns, the ancestors of modern palms, conifers and ginkgo trees.

In the seas and oceans, the dominance belonged to the algae that form the reefs.

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

1. Northern, dominated by herbaceous ferns and gingko trees;
2. Southern.

   Treelike ferns and cicadas reigned here.

In the modern world, ferns, cycads (palms reaching 18 meters in size) and kordaites of that time can be found in tropical and subtropical forests.

Horsetails, moss, cypresses and spruce trees practically did not differ from those that are common in our time.

The Cretaceous period is characterized by the emergence of plants with flowers. In this regard, butterflies and bees appeared among insects, thanks to which flowering plants were able to quickly spread across the planet.

Also at this time, ginkgo trees begin to grow with foliage falling off in the cold season. Coniferous forests of this time period are very similar to modern ones.

These include yews, firs and cypresses.

The development of higher gymnosperms continues 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 cicada and bennettite.

In appearance, cicadas resemble tree ferns or cycads. They have straight stems and massive leaves that look like feathers. Bennettites are trees or shrubs. Outwardly they are similar to cicadas, but their seeds are covered with a shell. This brings the plants closer to angiosperms.

In the Cretaceous period, angiosperms appear. From this moment a new stage in the development of plant life begins. Angiosperms (flowering) are at the top of the evolutionary ladder.

They have special reproductive organs - stamens and pistil, which are located in the flower bowl. Their seeds, in contrast to gymnosperms, are hidden by a dense protective shell. These plants of the Mesozoic era quickly adapt to any climatic conditions and are actively developing. In a short time, angiosperms began to dominate the entire Earth. Their various types and forms have reached the modern world - eucalyptus, magnolias, quince, oleanders, walnut trees, oaks, birches, willows and beeches.

Of the gymnosperms of the Mesozoic era, only coniferous species are now familiar to us - fir, pines, sequoias and some others. The evolution of plant life of that period significantly outstripped 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 advanced creatures was formed, which gradually replaced the ancient species.

One of these types of reptiles has become animal-like pelicosaurs - sailing dinosaurs.

On their backs was a huge sail, like 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 speed and endurance, therapsids were much superior to the pelicosaurs, but this did not save their species from extinction at the end of the Mesozoic era.

The evolutionary group of dinosaurs, from which mammals would later emerge, are the cynodonts (dog teeth). These animals got their name due to the powerful jaw bones and sharp teeth, with which they could easily chew raw meat.

Their bodies were covered with thick hair. The females laid eggs, but the newborn calves fed on their mother's milk.

At the beginning of the Mesozoic era, a new species of lizards was formed - archosaurs (ruling reptiles).

They are the ancestors of all dinosaurs, pterosaurs, plesiosaurs, ichthyosaurs, placodonts, and crocodylomorphs. The archosaurs, adapted to the climatic conditions on the coast, became predatory thecodonts.

They hunted on land near bodies of water. Most of the Thecodonts walked on four legs. But there were also individuals who ran on their hind legs. In this way, these animals developed incredible speed. Over time, the thecodonts evolved into dinosaurs.

By the end of the Triassic period, two species of reptiles predominated. Some are the ancestors of the crocodiles of our time.

Others turned out to be dinosaurs.

Dinosaurs are not similar in body structure to other dinosaurs. 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 the fast coelophysis, powerful herrerasaurs and huge plateosaurs.

In addition to dinosaurs, archosaurs laid the foundation for another type of reptile that is different from the rest.

These are pterosaurs - the first dinosaurs that can fly. They lived near water bodies, and ate various insects for food.

The fauna of the depths of the Mesozoic era is also characterized by a variety of species - ammonites, bivalve molluscs, shark families, bone and ray-finned fish. The most prominent predators were the underwater lizards that appeared not so long ago. Dolphin-like ichthyosaurs had a high speed.

One of the giant representatives of ichthyosaurs is the Shonisaurus. Its length reached 23 meters, and its weight did not exceed 40 tons.

Lizard-like notosaurs had sharp fangs.

Placadonts, similar to modern newts, were looking for shells of mollusks on the seabed, which they bit with their teeth. The tanystrophies lived on land. Long (2-3 times larger than body size), slender necks allowed them to catch fish while standing on the shore.

Another group of sea lizards of the Triassic period - plesiosaurs. At the beginning of the era, plesiosaurs reached a size of only 2 meters, and by the middle of the Mesozoic they evolved into giants.

The Jurassic period is the time of the development of the dinosaurs.

The evolution of plant life gave impetus to the emergence of different species of herbivorous dinosaurs. And this, in turn, led to an increase in the number of predatory individuals. Some dinosaur species were about the size of a cat, while others were about the size of giant whales. The most gigantic individuals are diplodocus and brachiosaurus, reaching lengths of 30 meters.

Their weight was about 50 tons.

Archeopteryx is the first creature standing on the border between lizards and birds. Archeopteryx were not yet able to fly long distances. Their beak was replaced by jaws with sharp teeth. The wings ended in fingers. Archeopteryx were about 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 rhamphorhynchia.

Pterodactyls lacked tail and feathers. But there were large wings and a narrow skull with few teeth. These creatures lived in flocks on the coast. During the day they got their food, and at night they hid in the trees. The pterodactyls ate fish, molluscs and insects. To climb into the sky, this group of pterosaurs had to jump from high places. The Rumphorhynchians also lived on the coast. They ate fish and insects. They had long tails with a lobe at the end, narrow wings and a massive skull with teeth of different sizes, which were convenient for catching slippery fish.

The most dangerous predator of the deep sea was Liopleurodon, which weighed 25 tons.

Huge coral reefs formed, in which ammonites, belemnites, sponges and marine mats settled. Representatives of the shark family and bony fish are developing. New species of plesiosaurs and ichthyosaurs, sea turtles and crocodiles have appeared. Saltwater crocodiles have flippers instead of legs. This feature allowed them to increase their speed in the aquatic environment.

In the Cretaceous period of the Mesozoic era, bees and butterflies appeared. The insects carried the pollen, and the flowers gave them food.

Thus began a long-term collaboration between insects and plants.

The most famous dinosaurs of that time were carnivorous tyrannosaurs and tarbosaurs, herbivorous bipedal iguanodons, tetrapods, rhino-like Triceratops, and small armored ankylosaurs.

Most mammals of this period belong to the subclass of allotheries.

These are small animals, similar to mice, weighing no more than 0.5 kg. The only exceptional species is the repenomama. 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 the alloteria. They were divided into 3 types - oviparous, marsupial and placental. They are the ones who replace dinosaurs at the beginning of the next era. From the placental species of mammals, rodents and primates emerged. Purgatorius are the first primates.

Modern possums evolved from the marsupial species, and the oviparous ones gave birth to platypuses.

Early pterodactyls and new species of flying reptiles - orcheopteryx and quetzatcoatls - reign in the air. These were the most gigantic flying creatures in the entire history of the development of our planet.

Birds dominate the air together with representatives of pterosaurs. In the Cretaceous period, many ancestors of modern birds appeared - ducks, geese, loons. The length of the birds was 4-150 cm, the weight was from 20 grams. up to several kilograms.

The seas were dominated by huge predators, reaching a length of 20 meters - ichthyosaurs, plesiosaurs and mososaurs. Plesiosaurs had a very long neck and small head.

The large size did not allow them to develop high speed. The animals ate fish and shellfish. Mososaurs have 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 reached the modern world unchanged. 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

A large number of deposits of natural resources are associated with the Mesozoic era.

These are sulfur, phosphorites, polymetals, construction 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 the Paleozoic era, but during this period several large deposits of brown and coal were formed - the Kansk basin, Bureinsky, Lensky.

Mesozoic oil and gas fields are located in the Urals, Siberia, Yakutia, and the Sahara.

Phosphorite deposits have been found in the Volga and Moscow regions.

To the table: aeon Phanerozoic

01 of 04. Periods of the Mesozoic era

The Paleozoic era, like all major eras on a geological time scale, ended with a mass extinction. The Permian mass extinction is considered the greatest loss of species in the history of the Earth. Almost 96% of all living species were destroyed due to the large number of volcanic eruptions that led to massive and relatively rapid climate change during the Mesozoic era.

The Mesozoic era is often referred to as the “era of the dinosaurs” because it is the time period in which dinosaurs evolved and eventually became extinct.

The Mesozoic era is divided into three periods: Triassic, Jurassic and Cretaceous.

02 of 04. Triassic Period (251 million years ago - 200 million years ago)

Fossil of Pseudopalatus from the Triassic period.

National Park Service

The beginning of the Triassic period was rather scarce in terms of life forms on Earth. Since there were so few species left after the Permian mass extinction, it took a very long time to repopulate and increase biodiversity. The topography of the Earth also changed during this time period. At the beginning of the Mesozoic era, all continents were united into one large continent. This supercontinent is called Pangea.

In the Triassic, continental separation began due to plate tectonics and continental drift.

When animals began to emerge from the oceans again and colonize almost empty land, they also learned to dig holes to protect themselves from environmental changes. For the first time in history, amphibians such as frogs appeared, followed by reptiles such as turtles, crocodiles, and ultimately dinosaurs.

Towards the end of the Triassic period, birds also appeared, separating from the dinosaur lineage in the phylogenetic tree.

Plants were also scarce. In the Triassic period, they began to flourish again.

Development of life in the Mesozoic era

Most of the terrestrial plants at that time were conifers or ferns. By the end of the Triassic period, some of the ferns had developed seeds for propagation. Unfortunately, another massive extinction ended the Triassic period. This time around 65% of the species on Earth did not survive.

03 of 04. Jurassic (200 million years ago - 145 million years ago)

A plesiosaur from the Jurassic period.

Tim Evanson

Following the Triassic mass extinction, life and species diversified to fill the niches that remained open. Pangea broke into two large parts - Laurasia was the land mass in the north, and Gondwana was in the south. Between these two new continents was the Tethys Sea. Diverse climates on every continent have allowed many new species to appear for the first time, including lizards and small mammals. Nevertheless, dinosaurs and flying reptiles continued to dominate on earth and in the sky.

There were many fish in the oceans.

Plants bloomed for the first time on earth. There were numerous extensive grazing grounds for herbivores, which also made it possible to feed the predators. The Jurassic was similar to the Renaissance for life on Earth.

04 of 04. Cretaceous Period (145 million years ago - 65 million years ago)

Fossil Cretaceous Pachycephalosaurus.

Tim Evanson

The Cretaceous period is the last period of the Mesozoic era. Favorable conditions for life on Earth lasted from the Jurassic period to the Early Cretaceous period. Laurasia and Gondwana began to grow even more, and eventually formed the seven continents that we see today. As the land expanded, the Earth's climate was warm and humid. These were very favorable conditions for plant life to flourish. Flowering plants began to multiply and dominate the land.

Since plant life was plentiful, the herbivore population also increased, which in turn led to an increase in the number and size of predators. Mammals also began to divide into many species, just as dinosaurs did.

Life in the ocean developed along a similar scenario. The warm and humid climate maintained high sea levels. This has contributed to an increase in the biodiversity of marine species.

All tropical areas of the Earth were covered with water, so the climatic conditions were largely ideal for a variety of life.

As before, these near-ideal conditions would have to end sooner or later. This time, it is believed that the mass extinction that ended the Cretaceous and then the entire Mesozoic era was caused by one or more large meteors hitting the Earth. Ash and dust ejected into the atmosphere blocked the sun, slowly killing off any lush plant life that had accumulated on land.

Likewise, most of the species in the ocean also disappeared during this time. As there were fewer and fewer plants, herbivores also gradually died out. Everything died out: from insects to large birds and mammals and, of course, dinosaurs. Only small animals that were able to adapt and survive in conditions of a small amount of food were able to see the beginning of the Cenozoic era.

Sources of

Mesozoic deposits- sediments, sediments formed in the Mesozoic era. Mesozoic deposits include Triassic, Jurassic and Cretaceous systems (periods).

Only Jurassic and Cretaceous sedimentary rocks are present in Mordovia. During the Triassic period (248 - 213 Ma) the territory of Mordovia was dry land and no precipitation was deposited. In the Jurassic period (213 - 144 million years), there was a sea throughout the republic, in which clays, sands, less often phosphorite nodules, and carbonaceous shales accumulated.

Jurassic deposits come to the surface on 20 - 25% of the area (mainly along river valleys), 80 - 140 m thick. They are associated with deposits of minerals - oil shale and phosphorites. In the Cretaceous period (144 - 65 million years) the sea continued to exist, and deposits of this age come to the surface on 60 - 65% of the territory in all regions of the Republic of Mordovia.

Represented by 2 groups - Lower and Upper Cretaceous. On the eroded surface of the Jurassic deposits (oil shales and dark clays), the Lower Cretaceous occurs: phosphorite conglomerate, greenish-gray and black clays and sands with a total thickness of up to 110 m.The Upper Cretaceous deposits consist of light gray and white chalk, marl, opoka and compose chalk mountains in the southeastern regions of the Republic of Mordovia.

Green glauconite and phosphorite-bearing sands are marked by thin layers. In other layers there are nodules and nodules of phosphorites, fossilized remains of organisms (belemnites, popularly called "devil's fingers"). The total thickness is about 80 m.

Mesozoic era

The Upper Cretaceous deposits are associated with the Atemarskoye and Kulyasovskoye chalk deposits, the Alekseevskoye field of cement raw materials.

[edit] Source

A. A. Mukhin. Open pit of the Alekseevsky cement plant. 1965 g.

Mesozoic era

The Mesozoic era began about 250 million years ago and ended 65 million years ago. It lasted 185 million years. The Mesozoic era is divided into Triassic, Jurassic and Cretaceous periods with a total duration of 173 million years. The deposits of these periods make up the corresponding systems, which together form the Mesozoic group.

The Mesozoic is known primarily as the era of the dinosaurs. These giant reptiles overshadow all other groups of living beings.

But you shouldn't forget about others. After all, it was the Mesozoic - the time when real mammals, birds, flowering plants appeared - in fact, the modern biosphere was formed.

And if in the first period of the Mesozoic - the Triassic, there were still many animals from the Paleozoic groups on Earth who were able to survive the Permian catastrophe, then in the last period - the Cretaceous, almost all those families that flourished in the Cenozoic era were already formed.

The Mesozoic era was a transitional period in the development of the earth's crust and life. It can be called the geological and biological Middle Ages.
The beginning of the Mesozoic era coincided with the end of the Variscian mountain-building processes; it ended with the beginning of the last powerful tectonic revolution - the Alpine folding.

In the Southern Hemisphere in the Mesozoic, the disintegration of the ancient continent of Gondwana was completed, but in general the Mesozoic era here was an era of relative calm, only occasionally and briefly disturbed by slight folding.

The early stage in the development of the plant kingdom, the paleophyte, was characterized by the dominance of algae, psilophytes and seed ferns. The rapid development of more highly developed gymnosperms, which characterizes the “vegetative Middle Ages” (mesophyte), began in the Late Permian era and ended by the beginning of the Late Cretaceous era, when the first angiosperms, or flowering, plants (Angiospermae) began to spread.

From the Late Cretaceous began kainophyte - the modern period of the development of the plant kingdom.

This made their resettlement much more difficult. The development of seeds allowed plants to lose their close dependence on water. The ovules could now be fertilized with pollen carried by the wind or insects, and the water thus no longer predetermined reproduction. In addition, unlike the unicellular spore with its relatively low supply of nutrients, the seed has a multicellular structure and is able to provide food for a young plant for a longer period in the early stages of development.

Under unfavorable conditions, the seed can remain viable for a long time. Having a strong shell, it reliably protects the embryo from external hazards. All these advantages gave seed plants a good chance of survival. The ovule (ovule) of the first seed plants was unprotected and developed on special leaves; the seed that arose from it also did not have an outer shell.

Among the most numerous and most curious gymnosperms of the beginning of the Mesozoic era, we find the Cycas, or sago. Their stems were straight and pillar-like, similar to tree trunks, or short and tuberous; they carried large, long and usually feathery leaves
(for example, the genus Pterophyllum, whose name means "feathery leaves").

Outwardly, they looked like tree ferns or palm trees.
In addition to cicadas, Bennettitales, represented by trees or shrubs, have acquired great importance in the mesophyte. Mostly they resemble true cicadas, but their seed begins to acquire a strong shell, which gives Bennettite a similarity to angiosperms.

There are other indications of adaptation of bennettites to arid climates.

In the Triassic, new forms come to the fore.

Conifers quickly settle, and among them are firs, cypresses, yews. Among the ginkgoids, the genus Baiera is widespread. The leaves of these plants were in the form of a fan-shaped plate deeply dissected into narrow lobes. Ferns have taken over damp shady places along the banks of small bodies of water (Hausmannia and other Dipteridacea). Known among ferns and forms growing on rocks (Gleicheniacae). Horsetails (Equisetites, Phyllotheca, Schizoneura) grew in the swamps, which, however, did not reach the size of their Paleozoic ancestors.
In the middle mesophyte (Jurassic period), the mesophytic flora reached the culmination point of its development.

The hot tropical climate in what is today the temperate zone was ideal for tree ferns to thrive, while smaller fern species and herbaceous plants preferred the temperate zone. Among the plants of this time, gymnosperms continue to play a dominant role
(primarily cicadas).

The Cretaceous period is marked by rare changes in vegetation.

The flora of the Lower Cretaceous is still reminiscent of the composition of the vegetation of the Jurassic period. Gymnosperms are still widespread, but their dominance ends by the end of this time.

Even in the Lower Cretaceous, the most progressive plants suddenly appear - angiosperms, the predominance of which characterizes the era of new plant life, or cainophyte.

Angiosperms, or flowering (Angiospermae), occupy the highest step of the evolutionary ladder of the plant kingdom.

Their seeds are encased in a strong shell; there are specialized reproductive organs (stamen and pistil), collected in 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 arid mountain climate with large temperature differences.
With the gradual cooling, which marked the chalk, they conquered more and more areas on the plains.

Quickly adapting to the new environment, they evolved at a tremendous rate. Fossils of the first true angiosperms are found in the Lower Cretaceous rocks of West Greenland, and a little later also in Europe and Asia. Within a relatively short time, they spread throughout the Earth and reached a great variety.

From the end of the Early Cretaceous, the balance of forces began to change in favor of the 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, magnolias, sassafras, tulip trees, Japanese quince trees (quince), brown laurels, walnut trees, plane trees, oleanders. These thermophilic trees coexisted with the typical flora of the temperate zone: oaks, beeches, willows, birches.

For gymnosperms, it was the time to hand over positions. Some species have survived to this day, but their total number went down all these centuries. A certain exception is conifers, which are found in abundance today.
In the Mesozoic, plants made a great leap forward, surpassing animals in the rate of development.

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.

Belemnite shells are popularly known as "devil's fingers". Ammonites were found in the Mesozoic in such an amount that their shells are found in almost all marine sediments of that time.

Ammonites appeared in the Silurian; they experienced their first heyday in the Devonian, but reached the highest diversity in the Mesozoic. More than 400 new genera of ammonites arose in the Triassic alone.

Ceratids were especially characteristic of the Triassic, widely distributed in the Upper Triassic sea basin of Central Europe, the deposits of which in Germany are known as shell limestone.

By the end of the Triassic, most of the ancient ammonite groups are dying out, but Phylloceratida survives in the Tethys, the giant Mesozoic Mediterranean. This group developed so rapidly in the Jurassic that the variety of forms of ammonites of this time surpassed the Triassic ones.

In the Cretaceous, cephalopods, both ammonites and belemnites, are still numerous, but during the Late Cretaceous, the number of species in both groups begins to decline. Among the ammonites at this time, aberrant forms with an incompletely twisted hook-shaped shell (Scaphites), with a shell elongated in a straight line (Baculites) and an irregularly shaped shell (Heteroceras) appear.

These aberrant forms appeared, most likely, as a result of changes in the course of individual development and narrow specialization. The terminal Upper Cretaceous forms of some ammonite branches are distinguished by sharply increased shell sizes. In the genus Parapachydiscus, for example, the shell diameter reaches 2.5 m.

The aforementioned belemnites also acquired great importance in the Mesozoic.

Some of their genera, for example, Actinocamax and Belenmitella, are important fossils and are successfully used for stratigraphic subdivision 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 the genus Nautilus has survived to this day. More widespread in modern seas are forms with an inner shell - octopuses, cuttlefish and squid, distantly related to belemnites.
The Mesozoic era was a time of unstoppable expansion of vertebrates. From the Paleozoic fish, only a few passed into the Mesozoic, as did the genus Xenacanthus, the last representative of the freshwater sharks of the Paleozoic, known from the freshwater sediments of the Australian Triassic.

Sea sharks continued to evolve throughout the Mesozoic; most modern genera were already represented in the Cretaceous seas, in particular, Carcharias, Carcharodon, lsurus, etc.

The ray-finned fish, which arose at the end of the Silurian, originally lived only in freshwater bodies of water, but with the Permians they begin to emerge into the seas, where they reproduce unusually from the Triassic to the present day and retain their dominant position.
The most widespread were reptiles in the Mesozoic, which became truly the dominant class of this era.

In the course of evolution, a variety of genera and species of reptiles appeared, often of very impressive sizes. Among them were the largest and most bizarre land animals that the earth has ever carried.

As already mentioned, in terms of anatomical structure, the oldest reptiles were close to labyrinthodonts. The oldest and most primitive reptiles were the hulking cotylosauria, which appeared in the early Middle Carboniferous and became extinct by the end of the Triassic. Among cotylosaurs, both small animal-eating forms and relatively large herbivorous forms (pareiasaurs) are known.

The descendants of cotylosaurs gave rise to all the diversity of the world of reptiles. One of the most interesting groups of reptiles that evolved from cotylosaurs were the animal-like (Synapsida, or Theromorpha), their primitive representatives (pelicosaurs) are known from the end of the Middle Carboniferous. In the middle of the Permian period, pelicosaurs, known mainly from North America, die out, but in the Old World they are replaced by more progressive forms that form the order of therapsids (Therapsida).
The predatory theriodonts (Theriodontia) included in it are already very similar to primitive mammals, and it is not by chance that it was from them that the first mammals developed by the end of the Triassic.

During the Triassic period, many new groups of reptiles appeared.

These are turtles, and ichthyosaurs ("fish lizard"), well adapted to sea life, resembling dolphins, and placodonts, clumsy armored animals with powerful flattened teeth adapted for crushing shells, and also plesiosaurs that lived in the seas, which had a relatively small head, more or less elongated neck, broad body, flipper-like paired limbs and short tail; plesiosaurs vaguely resemble giant shellless turtles.

In the Jurassic, plesiosaurs, like ichthyosaurs, flourished. Both of these groups remained very numerous in the Early Cretaceous, being extremely characteristic predators of the Mesozoic seas.
From an evolutionary point of view, one of the most important groups of Mesozoic reptiles were the thecodonts, medium-sized predatory reptiles of the Triassic period, which gave rise to the most diverse groups - crocodiles, dinosaurs, flying lizards, and, finally, birds.

However, the most remarkable group of Mesozoic reptiles were the well-known dinosaurs.

They evolved from the thecodonts in the Triassic and occupied a dominant position on Earth in the Jurassic and Cretaceous. Dinosaurs are represented by two groups, completely separate - lizards (Saurischia) and ornithischia (Ornithischia). In the Jurassic, among the dinosaurs, one could find real monsters, up to 25-30 m long (with a tail) and weighing up to 50 tons. Of these giants, such forms as Brontosaurus, Diplodocus and Brachiosaurus are the most famous.

And in the Cretaceous period, the evolutionary progress of dinosaurs continued. Of the European dinosaurs of this time, bipedal iguanodonts are widely known; in America, four-legged horned dinosaurs (Triceratops) (Styracosaurus, etc.), somewhat reminiscent of modern rhinos, became widespread.

Relatively small armored dinosaurs (Ankylosauria) covered with massive bony armor are also interesting. All of these forms were herbivorous, as were the giant platypus dinosaurs (Anatosaurus, Trachodon, etc.), which moved on two legs.

In the Cretaceous, predatory dinosaurs also flourished, the most remarkable of which were such forms as Tyrannosaurus rex, whose length exceeded 15 m, Gorgosaurus and Tarbosaurus.

All of these forms, which turned out to be the greatest terrestrial predatory animals in the entire history of the Earth, moved on two legs.

At the end of the Triassic, the first crocodiles also originated from the thecodonts, which became abundant only in the Jurassic period (Steneosaurus and others). In the Jurassic period, flying lizards appear - pterosaurs (Pterosauria), also descended from thecodonts.
Among the flying lizards of the Jurassic, the most famous are Rhamphorhynchus and Pterodactylus, of the Cretaceous forms the most interesting is the relatively very large Pteranodon.

Flying lizards become extinct by the end of the Cretaceous.
In the Cretaceous seas, giant predatory lizards-mosasaurs, exceeding 10 m in length, are widespread.Among modern lizards, they are closest to monitor lizards, but differ from them, in particular, in flipper-like limbs.

By the end of the Cretaceous, the first snakes (Ophidia) appeared, apparently descended from lizards that led a burrowing way of life.
By the end of the Cretaceous, there is a mass extinction of characteristic Mesozoic groups of reptiles, including dinosaurs, ichthyosaurs, plesiosaurs, pterosaurs and mosasaurs.

Representatives of the class of birds (Aves) first appear in the Jurassic sediments.

Brief information about the Mesozoic era

Remains of Archeopteryx, a widely known and so far the only known pioneer bird, were found in lithographic schists of the Upper Jurassic, near the Bavarian city of Solnhofen (FRG). In the Cretaceous, birds evolved rapidly; the typical genera of this time were Ichthyornis and Hesperornis, which still had teeth with teeth.

The first mammals (Mattalia), 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 was the Triconodonta, to which the most famous of the Triassic mammals, Morganucodon, belongs. Appears in the Jurassic
a number of new groups of mammals - Symmetrodonta, Docodonta, Multituberculata and Eupantotheria.

Of all the groups named by the Mesozoic, only Multituberculata (multi-tubercular) survived, the last representative of which dies out in the Eocene. The multi-cusp were the most specialized of the Mesozoic mammals, convergently they bore some resemblance to rodents.

The ancestors of the main groups of modern mammals - marsupials (Marsupialia) and placentals (Placentalia) were Eupantotheria. Both marsupials and placentals appeared in the Late Cretaceous. The most ancient group of placentals are insectivores (lnsectivora), which have survived to our time.

Mesozoic era

Mesozoic(Mesozoic era, from the 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 Phanerozoic eras. First identified in 1841 by the British geologist John Phillips.

The Mesozoic is an era of tectonic, climatic and evolutionary activity. The formation of the main contours of modern continents and mountain building on the periphery of the Pacific, Atlantic and Indian oceans is taking place; the division of land contributed to speciation and other important evolutionary events. The climate was exceptionally warm throughout the entire time period, which also played an important role in the evolution and formation of new animal species. By the end of the era, the bulk of the species diversity of life approached its present 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 periods, in the following order (beginning - end, million years ago):

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

The lower (between the Permian and Triassic periods, that is, between the Paleozoic and Mesozoic) boundary is marked by the massive Permian-Triassic extinction, as a result of which approximately 90-96% of the marine fauna and 70% of land vertebrates died. The upper limit was established at the turn of the Cretaceous and Paleocene, when there was another very large extinction of many groups of plants and animals, most often explained by the fall of a giant asteroid (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

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

Links

Wikimedia Foundation. 2010.

• Mesoamerican writing systems
• Mesocaryotes

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

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

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

MESOZOIC ERA- the second after the Precambrian era of geol. history of the Earth with a duration of 160 170 million years. Divided into 3 periods: Triassic, Jurassic and Cretaceous. Geological Dictionary: in 2 volumes. M .: Nedra. Edited by K. N. Paffengolts and others. 1978 ... Geological encyclopedia

Mesozoic era- Mesozoic Mesozoic (about the period) (geol.) Topics oil and gas industry Synonyms Mesozoic Mesozoic (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, which followed the Paleozoic era and preceded the Cenozoic era, to which geologists also attribute the period we are experiencing. Deposits of the M. era make up the M. group of layers ... Encyclopedic Dictionary of F.A. Brockhaus and I.A. Efron

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

Mesozoic era- geol. The era in the geological history of the Earth, following the Paleozoic and preceding the Cenozoic (subdivided into three periods: Triassic, Jurassic and Cretaceous) My breeds (of this time) ... Dictionary of many expressions

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

secondary or Mesozoic era- Mesozoic (geol.) - Topics oil and gas industry Synonyms Mesozoic (geol.) EN Secondary era ... Technical translator's guide

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

Books

• Dinosaurs. The Complete Encyclopedia, Green Tamara. 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 movie `Park ...

Mesozoic era

The Mesozoic era is the era of middle life. It is named so because the flora and fauna of this era are transitional between the Paleozoic and Cenozoic. In the Mesozoic era, the modern outlines of continents and oceans, modern marine fauna and flora are gradually formed. The Andes and Cordillera, the mountain ranges of China and East Asia were formed. The troughs of the Atlantic and Indian oceans were formed. The formation of the troughs of the Pacific Ocean began.

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

Triassic

The Triassic period got its name from the fact that three different rock complexes are ranked among its sediments: the lower one is continental sandstone, the middle one is limestone and the upper one is naper.

The most characteristic deposits of the Triassic period are: continental sandy-argillaceous rocks (often with coal lenses); marine limestones, clays, shales; lagoon anhydrites, salts, gypsum.

In the Triassic period, the northern continent of Laurasia merged with the southern one - Gondwana. The great bay, which began in the east of Gondwana, extended all the way to the northern coast of present-day Africa, then turned south, almost completely separating Africa from Gondwana. A long bay stretched from the west, separating the western part of Gondwana from Laurasia. Many depressions arose in Gondwana, which were gradually filled with continental sediments.

In the Middle Triassic, volcanic activity intensified. The inland seas become shallow, and numerous depressions are formed. The formation of the mountain ranges of South China and Indonesia begins. On the territory of the modern Mediterranean, the climate was warm and humid. It was cooler and wetter in the Pacific. Deserts dominated the territory of Gondwana and Laurasia. The climate of the northern half of Laurasia was cold and dry.

Along with changes in the distribution of the sea and land, the formation of new mountain ranges and volcanic regions, some animals and plant forms were intensively replaced by others. Only a few families passed from the Paleozoic to the Mesozoic. This gave rise to some researchers to assert about the great catastrophes that occurred at the turn of the Paleozoic and Mesozoic. However, when studying the deposits of the Triassic period, one can easily make sure that there is no sharp line between them and the Permian deposits, therefore, some forms of plants and animals were replaced by others, probably gradually. The main reason was not catastrophes, but the evolutionary process: more perfect forms gradually replaced less perfect ones.

Seasonal changes in temperatures during the Triassic period began to have a noticeable effect on plants and animals. Separate groups of reptiles have adapted to the cold seasons. It is from these groups that mammals originated in the Triassic, and somewhat later also birds. At the end of the Mesozoic era, the climate became even colder. Deciduous woody plants appear, which in cold seasons partially or completely shed their leaves. This feature of plants is an adaptation to colder climates.

Cooling in the Triassic period was insignificant. It manifested itself most strongly in the northern latitudes. The rest of the territory was warm. Therefore, the reptiles felt quite well in the Triassic period. Their most diverse forms, with which small mammals were not yet able to compete, settled over the entire surface of the Earth. The extraordinary flowering of reptiles was also facilitated by the rich vegetation of the Triassic period.

Giant forms of cephalopods have developed in the seas. The diameter of the shells of some of them was up to 5 m. True, and now gigantic cephalopods, such as squid, reaching 18 m in length, live in the seas, but in the Mesozoic era there were much more gigantic forms.

The composition of the atmosphere of the Triassic period compared with the Permian period changed little. The climate became more humid, but the deserts in the center of the continent remained. Some plants and animals of the Triassic period have survived to this day in the region of Central Africa and South Asia. This suggests that the composition of the atmosphere and the climate of individual land areas remained almost unchanged during the Mesozoic and Cenozoic eras.

And yet Stegocephalus became extinct. They were supplanted by reptiles. More advanced, mobile, well adapted to a variety of living conditions, they ate the same food as stegocephals, settled in the same places, ate young stegocephals and ultimately exterminated them.

Among the Triassic flora, calamites, seed ferns, and cordaites were still found occasionally. Real ferns, ginkgo, bennetite, cycads, and conifers prevailed. Cycads still exist in the area of ​​the Malay Archipelago. They are known as sago palms. In appearance, cycads occupy an intermediate place between palms and ferns. The trunk of cycads is rather thick, columnar. The crown consists of tough, feathery leaves arranged in a corolla. Plants reproduce with the help of macro- and microspores.

Triassic ferns were coastal herbaceous plants with wide dissected leaves with reticulated veins. From conifers, voltages are well studied. She had a dense crown and such, like those of a spruce, cones.

Ginkgoids were quite tall trees, their leaves formed dense crowns.

A special place among the Triassic gymnosperms was occupied by bennetites - trees with whorled large complex leaves resembling those of cycads. The reproductive organs of bennetites occupy an intermediate place between the cones of cycads and the flowers of some flowering plants, in particular magnolia. Thus, it is probably the bennetites that should be considered the ancestors of flowering plants.

All types of animals that exist in our time are already known from the invertebrates of the Triassic period. The most characteristic marine invertebrates were reef-forming animals and ammonites.

In the Paleozoic, animals already existed that covered the bottom of the sea in colonies, forming reefs, although not very powerful. During the Triassic period, when many colonial six-rayed corals appear instead of tabuli, reefs up to a thousand meters thick begin to form. The cups of the six-rayed corals had six or twelve calcareous septa. As a result of the massive development and rapid growth of corals on the seabed, underwater forests were formed, in which numerous representatives of other groups of organisms settled. Some of them took part in reef formation. Bivalves, algae, sea urchins, starfish, sponges lived between the corals. Destroyed by waves, they formed coarse-grained or fine-grained sand that filled all the voids of the corals. Washed by waves from these voids, lime mud was deposited in bays and lagoons.

Some bivalve molluscs are quite typical for the Triassic period. Their thin, paper-like shells with brittle ribs in some cases form whole layers in the sediments of this period. Bivalve mollusks lived in shallow muddy bays - lagoons, on reefs and between them. In the Upper Triassic, many thick-shell bivalves appear, firmly attached to the limestone deposits of shallow-water basins.

At the end of the Triassic, due to increased volcanic activity, part of the limestone deposits were covered with ash and lavas. The steam rising from the bowels of the Earth brought with it many compounds, from which deposits of non-ferrous metals were formed.

Prosobranchs were the most common gastropods. Ammonites were widespread in the seas of the Triassic period, the shells of which in some places accumulated in huge quantities. Appearing in the Silurian period, they did not play a large role among other invertebrates throughout the Paleozoic era. Ammonites could not successfully compete with rather complex nautiloids. The shells of ammonites were formed from calcareous plates, which had the thickness of tissue paper and therefore almost did not protect the soft body of the mollusk. Only when their partitions bent into numerous folds, the shells of the ammonites gained strength and turned into a real shelter from predators. With the increasing complexity of the partitions, the shells became even more durable, and the outer structure gave them the opportunity to adapt to the most diverse living conditions.

Echinoderms were represented by sea urchins, lilies and stars. At the upper end of the body of the sea lilies was a flower-like main body. It distinguishes between the corolla and the grasping organs - "hands". The mouth and anus were located between the "hands" in the corolla. With its "hands" the sea lily raked water into the mouth opening, and with it the sea animals that it ate. Many Triassic sea lilies have a spiral stem.

The Triassic seas were inhabited by calcareous sponges, bryozoans, leaf-footed crayfish, ostracods.

The fish were represented by sharks living in fresh water bodies and molluscoids inhabiting the sea. The first primitive bony fish appear. Powerful fins, well-developed dental apparatus, perfect shape, strong and lightweight skeleton - all this contributed to the rapid spread of teleost fishes in the seas of our planet.

Amphibians were represented by stegocephals from the labyrinthodont group. They were sedentary animals with a small body, small limbs and a large head. They lay in the water waiting for prey, and when the prey approached, they grabbed it. Their teeth had a complex labyrinthine folded enamel, which is why they were called labyrinthodonts. The skin was moistened with mucous glands. Other amphibians went ashore to hunt insects. The most typical representatives of labyrinthodonts are mastodonosaurs. These animals, whose skulls reached one meter in length, resembled huge frogs in appearance. They hunted fish and therefore rarely left the aquatic environment.

Mastodonosaurus.

The swamps became smaller, and the mastodonosaurs were forced to populate ever deeper places, often accumulating in large numbers. That is why many of their skeletons are now being found in small areas.

Reptiles in the Triassic are characterized by significant diversity. New groups appear. Of the cotylosaurs, only the procolophones remain - small animals that fed on insects. An extremely curious group of reptiles was represented by the archosaurs, to which the thecodonts, crocodiles and dinosaurs belonged. Representatives of thecodonts, ranging in size from a few centimeters to 6 m, were predators. They also differed in a number of primitive features and resembled the Permian pelicosaurs. Some of them - pseudosuchia - had long limbs, a long tail and led a terrestrial lifestyle. Others, including the crocodile phytosaurs, lived in the water.

Crocodiles of the Triassic period - small primitive animals of protosuchia - lived in fresh water.

Theropods and prosauropods appear among dinosaurs. Theropods moved on well-developed hind limbs, had a heavy tail, powerful jaws, and small and weak forelimbs. The size of these animals ranged from a few centimeters to 15 m. All of them belonged to predators.

As a rule, prosauropods ate plants. Some of them were omnivores. They walked on four legs. Prosauropods had a small head, long neck and tail.

Representatives of the subclass of synaptosaurs led a wide variety of lifestyles. Trilophosaurus climbed trees, ate plant foods. He looked like a cat in appearance.

Seal-like reptiles lived off the coast, feeding mainly on mollusks. Plesiosaurs lived in the sea, but sometimes came ashore. They reached 15 m in length. They ate fish.

In some places, footprints of a huge animal that walked on four legs are often found. It was called the chiroterium. From the surviving prints, one can imagine the structure of the foot of this animal. Four clumsy toes encircled a thick, fleshy sole. Three of them had claws. The forelimbs of the chiroterium are almost three times smaller than the hind ones. The animal left deep footprints on the wet sand. With the deposition of new layers, the tracks gradually petrified. Later, the land was flooded with sea, which hid the tracks. They turned out to be covered with marine sediments. Consequently, in that era, the sea was repeatedly flooded. The islands sank below sea level, and the animals living on them were forced to adapt to new conditions. Many reptiles appear in the sea, which undoubtedly descended from continental ancestors. Turtles with wide bony shells, dolphin-like ichthyosaurs - fish-lizards and gigantic plesiosaurs with a small head on a long neck - developed rapidly. Their vertebrae are transformed, limbs change. The cervical vertebrae of the ichthyosaur grow together into one bone, and in turtles they grow, forming the upper part of the shell.

The ichthyosaurus had a number of homogeneous teeth; in turtles, the teeth disappear. The five-toed limbs of ichthyosaurs turn into flippers well adapted for swimming, in which it is difficult to distinguish between the shoulder, forearm, wrist and finger bones.

Since the Triassic period, reptiles that have gone to live in the sea gradually populate more and more vast expanses of the ocean.

The oldest mammal found in the Triassic deposits of North Carolina is called dromaterium, which means "running animal." This "beast" was only 12 cm long. Dromaterium belonged to oviparous mammals. They, like the modern Australian echidna and the platypus, did not give birth to young, but laid eggs, from which the underdeveloped cubs hatched. Unlike reptiles, who did not take care of their offspring at all, dromateriums fed their young with milk.

Deposits of the Triassic period are associated with deposits of oil, natural gases, brown and coal, iron and copper ores, rock salt.

The Triassic period lasted 35 million years.

Jurassic period

For the first time, deposits of this period were found in the Jurah (mountains in Switzerland and France), hence the name of the period. The Jurassic period is subdivided into three divisions: Layas, Doger, and Malm.

The deposits of the Jurassic period are quite diverse: limestones, clastic rocks, shales, igneous rocks, clays, sands, conglomerates, formed in a variety of conditions.

Sedimentary rocks containing many representatives of fauna and flora are considerably widespread.

Intense tectonic movements in the late Triassic and early Jurassic periods contributed to the deepening of large bays that gradually separated Africa and Australia from Gondwana. The bay between Africa and America has deepened. Depressions formed in Laurasia: German, Anglo-Parisian, West Siberian. The Arctic Sea flooded the northern coast of Laurasia.

Intense volcanism and mountain building processes led to the formation of the Verkhoyansk folded system. The formation of the Andes and the Cordilleras continued. Warm sea currents have reached arctic latitudes. The climate became warm and humid. This is evidenced by the significant distribution of coral limestones and the remains of thermophilic fauna and flora. There are very few deposits of a dry climate: lagoon gypsum, anhydrite, salt and red sandstone. The cold season already existed, but it was characterized only by a drop in temperature. There was no snow or ice.

The climate of the Jurassic period depended on more than just sunlight. Numerous volcanoes, outpouring of magma to the bottom of the oceans warmed up the water and the atmosphere, saturated the air with water vapor, which then rained down onto land, and flowed into lakes and oceans in violent streams. This is evidenced by numerous freshwater deposits: white sandstones alternating with dark loams.

The warm and humid climate favored the flourishing of the flora. Ferns, cicadas, conifers formed vast swampy forests. Araucaria, thuja, and cicadas grew on the coast. Ferns and horsetails formed the undergrowth. In the Lower Jurassic, the vegetation was rather uniform throughout the northern hemisphere. But already starting from the Middle Jurassic, two plant belts can be identified: the northern one, in which ginkgo and herbaceous ferns predominated, and the southern one with bennetites, cicadas, araucaria, and tree ferns.

The characteristic ferns of the Jurassic period were matonia, which have survived to this day in the Malay archipelago. Horsetails and baluns hardly differed from modern ones. The place of extinct seed ferns and kordaites is taken by cycads, which still grow in tropical forests.

Ginkgo beetles were also widely spread. Their leaves turned to the sun with an edge and resembled huge fans. From North America and New Zealand to Asia and Europe, there were dense forests of conifers - araucaria and bennetite. The first cypress and possibly spruce trees appear.

The representatives of the Jurassic conifers also include the sequoia - the modern giant Californian pine. Currently, sequoias remain only on the Pacific coast of North America. Some forms of even more ancient plants have survived, such as glassopteris. But such plants are few, since they have been supplanted by more perfect ones.

The lush vegetation of the Jurassic period contributed to the widespread distribution of reptiles. Dinosaurs have developed significantly. Among them, there are lizards and poultry. Lizards moved on four legs, had five toes on their feet, and ate plants. Most of them had long necks, small heads, and long tails. They had two brains: one small - in the head; the second is much larger in size - at the base of the tail.

The largest of the Jurassic dinosaurs was the Brachiosaurus, reaching a length of 26 m and weighing about 50 tons. It had columnar legs, a small head, and a thick long neck. Brachiosaurs lived on the shores of the Jurassic lakes, fed on aquatic vegetation. Brachiosaurus needed at least half a ton of green mass every day.

Brachiosaurus.

Diplodocus is the oldest reptile, its length was 28 m. It had a long thin neck and a long thick tail. Like brachiosaurus, the diplodocus moved on four legs, the hind legs were longer than the front ones. Diplodocus spent most of its life in swamps and lakes, where it grazed and escaped from predators.

Diplodocus.

The Brontosaurus was relatively tall, with a large hump on its back and a thick tail. Its length was 18 m. The vertebrae of the brontosaurus were hollow. Chisel-shaped small teeth were densely located on the jaws of the small head. Brontosaurus lived in swamps, on the shores of lakes.

Brontosaurus.

Avian dinosaurs are subdivided into bipeds and tetrapods. Different in size and appearance, they fed mainly on vegetation, but predators are already appearing among them.

Stegosaurs are herbivores. They had two rows of large plates on their backs and paired spines on their tail, which protected them from predators. Many scaly lepidosaurs appear - small predators with beak-like jaws.

In the Jurassic period, flying lizards first appear. They flew with the help of a leathery shell stretched between the long finger of the hand and the bones of the forearm. Flying lizards were well adapted to flight. They had light tubular bones. The extremely elongated outer fifth toe of the forelimbs consisted of four joints. The first finger looked like a small bone or was completely absent. The second, third and fourth fingers consisted of two, less often three bones and had claws. The hind legs were quite well developed. They had sharp claws at their ends. The skull of flying lizards was relatively large, usually elongated and pointed. In old lizards, the cranial bones fused together and the skulls became similar to the skulls of birds. The intermaxillary bone sometimes grew into an elongated toothless beak. Toothed dinosaurs had simple teeth and sat in recesses. The largest teeth were in front. Sometimes they stuck out to the side. This helped the lizards to catch and hold on to their prey. The vertebral column of the animals consisted of 8 cervical, 10–15 dorsal, 4–10 sacral, and 10–40 caudal vertebrae. The ribcage was wide and had a high keel. The shoulder blades were long, the pelvic bones were fused. The most typical representatives of flying lizards are pterodactyl and ramphorhynchus.

Pterodactyl.

In most cases, pterodactyls were tailless, varying in size - from the size of a sparrow to a crow. They had broad wings and a narrow, forward-elongated skull with few teeth in the front. Pterodactyls lived in large flocks on the shores of the lagoons of the Late Jurassic Sea. During the day they hunted, and at nightfall they hid in trees or in rocks. The skin of the pterodactyls was wrinkled and bare. They ate mainly fish, sometimes sea lilies, molluscs, insects. In order to take off, pterodactyls had to jump off rocks or trees.

Rumphorhynchians had long tails, long narrow wings, and a large skull with numerous teeth. Long teeth of various sizes were bent forward. The tail of the lizard ended with a blade that served as a rudder. Rumphorhynchians could take off from the ground. They settled on the banks of rivers, lakes and seas, and ate insects and fish.

Ramforinch.

Flying lizards lived only in the Mesozoic era, and their heyday falls on the late Jurassic period. Their ancestors were, apparently, extinct ancient reptiles pseudosuchia. Long-tailed forms appeared earlier than short-tailed ones. They became extinct at the end of the Jurassic period.

It should be noted that flying lizards were not the ancestors of birds and bats. Flying lizards, birds and bats have originated and developed each in their own way, and there are no close family ties between them. The only common sign for them is the ability to fly. And although they all acquired this ability due to the change in their forelimbs, the differences in the structure of their wings convince us that they had completely different ancestors.

The seas of the Jurassic period were inhabited by dolphin-like reptiles - ichthyosaurs. They had a long head, sharp teeth, large eyes, surrounded by a bony ring. The length of the skull of some of them was 3 m, and the length of the body was 12 m. The limbs of ichthyosaurs consisted of bony plates. The elbow, metatarsus, hand and fingers differed little in shape from each other. About a hundred bone plates supported a wide flipper. The shoulder and pelvic girdles were poorly developed. There were several fins on the body. Ichthyosaurs were viviparous animals. Plesiosaurs lived alongside ichthyosaurs. They had a thick body with four flipper-like limbs, a long serpentine neck with a small head.

In the Jurassic period, new genera of fossil turtles appeared, and at the end of the period, modern turtles appeared.

Tailless frog-like amphibians lived in fresh water bodies. In the Jurassic seas there were a lot of fish: bony, stingrays, sharks, cartilaginous, ganoid. They had an internal skeleton made of flexible cartilaginous tissue saturated with calcium salts: a dense bone scaly cover that protected them well from enemies, and jaws with strong teeth.

Among the invertebrates in the Jurassic seas were found ammonites, belemnites, sea lilies. However, in the Jurassic period, there were much fewer ammonites than in the Triassic. Jurassic ammonites differ from Triassic ones also in their structure, with the exception of phyloceras, which did not change at all during the transition from the Triassic to the Jurassic. Separate groups of ammonites have preserved mother-of-pearl to our time. Some animals lived in the open sea, others - inhabited bays and shallow inland seas.

Cephalopods - belemnites - swam in whole flocks in the Jurassic seas. Along with small specimens, there were real giants - up to 3 m long.

Remnants of the inner shells of belemnites, known as "devil's fingers", are found in the deposits of the Jurassic period.

In the seas of the Jurassic period, bivalve molluscs also developed significantly, especially those belonging to the oyster family. They start to form oyster banks.

Sea urchins living on reefs undergo significant changes. Along with the round forms that have survived to this day, bilaterally symmetrical irregular-shaped hedgehogs lived. Their body was stretched out in one direction. Some of them had a jaw apparatus.

The Jurassic seas were relatively shallow. Rivers brought muddy water into them, retarding gas exchange. Deep bays were filled with rotting remains and silt containing a large amount of hydrogen sulfide. That is why in such places the remains of animals, carried by sea currents or waves, are well preserved.

Sponges, starfish, sea lilies often overwhelm the Jurassic deposits. During the Jurassic period, the "five-armed" sea lilies were widely spread. Many crustaceans appear: barnacles, decapods, leaf-footed crayfish, freshwater sponges, among insects - dragonflies, beetles, cicadas, bugs.

In the Jurassic period, the first birds appear. Their ancestors were the ancient reptiles pseudosuchia, which also gave rise to dinosaurs and crocodiles. Ornithosuchia is most similar to birds. She, like birds, moved on her hind legs, had a strong pelvis and was covered with feather-like scales. Some of the pseudo-aids moved to live on trees. Their forelimbs were specialized to wrap their fingers around branches. There were lateral depressions on the skull of the pseudosuchia, which significantly reduced the mass of the head. Climbing trees and jumping on branches strengthened the hind limbs. The gradually widening forelimbs supported the animals in the air and allowed them to glide. As an example of such a reptile, you can point out the scleroholes. His long, thin legs indicate that he jumped well. Elongated forearms helped the animals climb and cling to branches of trees and bushes. The most important moment in the transformation of reptiles into birds was the transformation of scales into feathers. The heart of the animals had four chambers, which ensured a constant body temperature.

In the late Jurassic period, the first birds appear - Archeopteryx, the size of a dove. In addition to short feathers, Archeopteryx had seventeen flight feathers on their wings. The tail feathers were located on all caudal vertebrae and were directed back and down. Some researchers believe that the feathers of the bird were bright, like those of modern tropical birds, others that the feathers were gray or brown, and still others that they were variegated. The mass of the bird reached 200 g. Many signs of Archeopteryx indicate its kinship with reptiles: three free fingers on the wings, a head covered with scales, strong conical teeth, and a tail consisting of 20 vertebrae. The vertebrae of the bird were biconcave, like those of fish. Archeopteryx lived in araucaria and cicada forests. They fed mainly on insects and seeds.

Archeopteryx.

Predators have appeared among mammals. Small in size, they lived in forests and dense bushes, hunting small lizards and other mammals. Some of them have adapted to life in trees.

Deposits of coal, gypsum, oil, salt, nickel and cobalt are associated with the Jurassic deposits.

This period lasted 55 million years.

Cretaceous period

The Cretaceous period got its name because powerful chalk deposits are associated with it. It is subdivided into two sections: lower and upper.

Mountain building processes at the end of the Jurassic period significantly changed the outlines of continents and oceans. North America, previously separated from the huge Asian mainland by a wide strait, joined with Europe. In the east, Asia joined America. South America completely separated from Africa. Australia was in the same place where it is today, but was smaller in size. The formation of the Andes and Cordilleras continues, as well as individual ranges of the Far East.

In the Upper Cretaceous, the sea flooded vast areas of the northern continents. Western Siberia and Eastern Europe, most of Canada and Arabia were under water. Thick strata of chalk, sands, marls are accumulating.

At the end of the Cretaceous period, mountain-building processes are again activated, as a result of which the mountain ranges of Siberia, Andes, Cordillera and mountain ranges of Mongolia were formed.

The climate has changed. In the high latitudes in the north, during the Cretaceous period, there was already a real winter with snow. Within the boundaries of the modern temperate zone, some tree species (walnut, ash, beech) did not differ in any way from modern ones. The leaves of these trees fell for the winter. However, as before, the climate as a whole was much warmer than today. Ferns, cycads, ginkgoids, bennetites, conifers, in particular sequoias, yews, pines, cypresses, and spruces, were still widespread.

In the middle of the Cretaceous period, flowering plants thrive. At the same time, they crowd out representatives of the most ancient flora - spore and gymnosperms. It is believed that flowering plants originated and developed in the northern regions, and they subsequently spread throughout the planet. Flowering plants are much younger than the conifers we have known since the Carboniferous period. The dense forests of giant tree ferns and horsetails had no flowers. They adapted well to the living conditions of that time. However, gradually the humid air of the primary forests became drier and drier. It rained very little, the sun was unbearably burning. The soil was drying up in the areas of primary bogs. Deserts arose on the southern continents. Plants have moved to cooler, wetter climates in the north. And then the rains came again, saturating the moist soil. The climate of ancient Europe has become tropical, forests arose on its territory, similar to the modern jungle. The sea is retreating again, and the plants that inhabited the coast in a humid climate found themselves in a drier climate. Many of them died, but some adapted to the new conditions of life, forming fruits that protected the seeds from drying out. The descendants of such plants gradually populated the entire planet.

The soil has also undergone changes. Silt, plant and animal remains enriched it with nutrients.

In primary forests, plant pollen was carried only by wind and water. However, the first plants appeared, the pollen of which was fed by insects. Part of the pollen adhered to the wings and legs of insects, and they transferred it from flower to flower, pollinating the plants. The seeds of the pollinated plants matured. Plants that were not visited by insects did not multiply. Therefore, only plants with fragrant flowers of the most varied forms and colors were distributed.

With the advent of flowers, insects have also changed. Among them, insects appear that cannot live without flowers at all: butterflies, bees. From the pollinated flowers, fruits with seeds developed. Birds and mammals ate these fruits and spread the seeds over long distances, spreading the plants to new areas of the continents. Many herbaceous plants have appeared that populated the steppes and meadows. The leaves of the trees crumbled in the fall, and curled up in the summer heat.

Plants spread over Greenland and the islands of the Arctic Ocean, where it was relatively warm. At the end of the Cretaceous period, with the cooling of the climate, many cold-resistant plants appeared: willow, poplar, birch, oak, viburnum, characteristic of the flora of our time.

With the development of flowering plants, bennetites died out by the end of the Cretaceous period, and the number of cycads, ginkgoids, and ferns decreased significantly. Fauna changed along with changes in vegetation.

Foraminifera, the shells of which formed thick chalk deposits, were widely distributed. The first nummulites appear. Corals formed reefs.

Ammonites of the Cretaceous seas had shells of a peculiar shape. If all the ammonites that existed before the Cretaceous period had shells wrapped in one plane, then the Cretaceous ammonites had elongated shells bent in the form of a knee, spherical and straight ones were encountered. The surface of the shells was covered with thorns.

According to some researchers, the bizarre shapes of the chalk ammonites are a sign of the aging of the entire group. Although some representatives of the ammonites continued to multiply at a high rate, their vital energy in the Cretaceous period almost dried up.

According to other scientists, ammonites were exterminated by numerous fish, crustaceans, reptiles, mammals, and the outlandish forms of chalk ammonites are not a sign of aging, but mean an attempt to somehow protect themselves from excellent swimmers, which by that time had become bony fish and sharks.

The disappearance of ammonites was also facilitated by a sharp change in physical and geographical conditions in the Cretaceous period.

Belemnites, which appeared much later than the ammonites, also completely die out in the Cretaceous. Among the bivalve molluscs there were animals, different in shape and size, which closed the valves with denticles and pits. In oysters and other molluscs that attach to the seabed, the valves become different. The lower flap looked like a deep bowl, and the upper one was a lid. Among the Rudists, the lower valve turned into a large thick-walled glass, inside which there was only a small chamber for the mollusk itself. The round, lid-like upper flap enclosed the lower flap with strong teeth, with which it could rise and fall. The Rudists lived mainly in the southern seas.

In addition to bivalve molluscs, whose shells consisted of three layers (outer horny, prismatic, and nacreous), there were mollusks with shells that had only a prismatic layer. These are mollusks of the genus Inoceramus, widely settled in the seas of the Cretaceous period, - animals that reached one meter in diameter.

During the Cretaceous period, many new species of gastropods appear. Among sea urchins, the number of irregular heart-shaped forms is especially increasing. And among the sea lilies there are varieties that do not have a stem and float freely in the water with the help of long feathery "arms."

Big changes have taken place among fish as well. In the seas of the Cretaceous period, ganoid fish are gradually dying out. The number of bony fish is increasing (many of them still exist in our time). Sharks are gradually taking on a modern look.

Numerous reptiles still lived in the sea. The descendants of ichthyosaurs that died out at the beginning of the Cretaceous period reached 20 m in length and had two pairs of short flippers.

New forms of plesiosaurs and pliosaurs appear. They lived on the high seas. Crocodiles and turtles inhabited freshwater and saltwater basins. The territory of modern Europe was inhabited by large lizards with long spines on the back and huge pythons.

Of the terrestrial reptiles for the Cretaceous period, trakhodons and horned lizards were especially characteristic. Trakhodons could move on both two and four legs. They had membranes between their toes to help them swim. The jaws of the trakhodons were like a duck's beak. They had up to two thousand small teeth.

Triceratops had three horns on their heads and a huge bone shield that reliably protected animals from predators. They lived mainly in dry places. They fed on vegetation.

Triceratops.

Styracosaurs had nasal outgrowths - horns and six horny spines on the posterior edge of the bony shield. Their heads were two meters long. Thorns and horns made Styracosaurs dangerous to many predators.

The most terrible predatory lizard was the tyrannosaurus. It reached a length of 14 m. Its skull, more than a meter long, had large, sharp teeth. The tyrannosaurus moved on powerful hind legs, leaning on a thick tail. His front legs were small and weak. From the tyrannosaurs, fossilized footprints remained, 80 cm long.The step of the tyrannosaurus was 4 m.

Tyrannosaur.

Ceratosaurus was a relatively small but fast predator. He had a small horn on his head, and a bone crest on his back. The ceratosaurus moved on its hind legs, each of which had three toes with large claws.

Torbosaurus was rather clumsy and hunted mainly on sedentary scolosaurs, which resembled modern armadillos in appearance. Thanks to their powerful jaws and strong teeth, torbosaurs easily gnawed through the thick bony shell of scolosaurs.

Scolosaurus.

Flying lizards continued to exist. The huge pteranodon, whose wingspan was 10 m, had a large skull with a long bony ridge at the back of the head and a long toothless beak. The animal's body was relatively small. The pteranodons ate fish. Like modern albatrosses, they spent most of their lives in the air. Their colonies were by the sea. Recently, the remains of another pteranodon were found in the Cretaceous deposits of America. Its wingspan reached 18 m.

Pteranodon.

Birds appear that could fly well. Archeopteryx is completely extinct. However, some birds had teeth.

In the hesperornis, a waterfowl, the long toe of the hind limbs was connected to three other short swimming membranes. All fingers had claws. Only slightly bent humeral bones in the form of a thin rod remained of the forelimbs. Hesperornis had 96 teeth. Young teeth grew inside old ones and replaced them as soon as they fell out. The Hesperornis is very similar to the modern loon. It was very difficult for him to move on land. Raising the front part of the body and pushing off the ground with his feet, the Hesperornis moved in small jumps. However, he felt at ease in the water. Dived well and it was very difficult for fish to avoid its sharp teeth.

Hesperornis.

Ichthyornis, contemporaries of the Hesperornis, were the size of a dove. They flew well. Their wings were strongly developed, and the sternum had a high keel, to which powerful pectoral muscles were attached. On the beak of the ichthyornis there were many small teeth bent back. The small brain of the ichthyornis resembled the brain of reptiles.

Ichthyornis.

In the Late Cretaceous period, toothless birds appear, whose relatives - flamingos - exist in our time.

Amphibians are no longer different from modern ones. And mammals are represented by predators and herbivores, marsupials and placentals. They do not yet play a significant role in nature. However, at the end of the Cretaceous period - the beginning of the Cenozoic era, when giant reptiles became extinct, mammals spread widely across the Earth, taking the place of dinosaurs.

There are many hypotheses regarding the causes of the extinction of the dinosaurs. Some researchers believe that the main reason for this was mammals, of which a lot appeared at the end of the Cretaceous period. Predatory mammals exterminated dinosaurs, and herbivores intercepted plant food from them. A large group of mammals ate dinosaur eggs. According to other researchers, the main reason for the mass death of dinosaurs was a sharp change in physical and geographical conditions at the end of the Cretaceous. Cooling and droughts led to a sharp decrease in the number of plants on Earth, as a result of which the dinosaur giants began to feel a lack of food. They died. And predators, for whom dinosaurs served as prey, also perished, since they had nothing to eat. Perhaps the sun's heat was not enough for embryos to ripen in dinosaur eggs. In addition, the cold snap had a detrimental effect on adult dinosaurs. Having no constant body temperature, they depended on the temperature of the environment. Like modern lizards and snakes, in warm weather they were active, and in cold weather they moved sluggishly, could fall into winter torpor and became easy prey for predators. Dinosaur skin did not protect them from the cold. And they hardly cared about their offspring. Their parental functions were limited to laying eggs. Unlike dinosaurs, mammals had a constant body temperature, and therefore they suffered less from cold snaps. In addition, they were protected by wool. And most importantly, they fed their young with milk, took care of them. Thus, mammals had certain advantages over dinosaurs.

The birds also survived, which had a constant body temperature and were covered with feathers. They incubated eggs, fed chicks.

Of the reptiles, those who sheltered from the cold in burrows that lived in warm areas survived. From them came modern lizards, snakes, turtles and crocodiles.

Large deposits of chalk, coal, oil and gas, marls, sandstones, and bauxites are associated with the Cretaceous deposits.

The Cretaceous period lasted 70 million years.

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