What era is the Jurassic period? Mesozoic period
The Mesozoic era is an era average life. The Mesozoic is a transitional stage between the Paleozoic and Cenozoic. During the Mesozoic era, the modern outlines of continents and oceans, modern marine fauna and flora gradually formed. The Andes and Cordillera, the mountain ranges of China and East Asia, were formed. The depressions of the Atlantic and Indian Oceans. The formation of the Pacific Ocean depressions began.
The Mesozoic era is divided into three periods:
- Triassic – 252-201 million years ago;
- Jurassic – 201-145 million years ago;
- Cretaceous - 145-66 million years ago.
Periods of the Mesozoic era
Triassic period (Triassic). The initial erathema of the Mesozoic era lasts 35 million years. This is the time of formation of the Atlantic Ocean. The single continent of Pangea again begins to break into two parts - Gondwana and Laurasia. Inland continental reservoirs are beginning to actively dry up. The depressions left from them are gradually filled with rock deposits. New mountain heights and volcanoes are appearing and exhibiting 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. The salt level in water bodies is rising. During this time period, representatives of birds, mammals and dinosaurs appear on the planet.
Jurassic period (Jura)- the most famous period of the Mesozoic era. It received its name due to the sedimentary deposits of that time found in the Jura (mountain ranges of Europe). The average period of the Mesozoic era lasts about 69 million years. The formation of modern continents begins - Africa, America, Antarctica, Australia. But they are not yet located in the order to which we are accustomed. Deep bays and small seas appear, separating the continents. Active formation of mountain ranges continues. The Arctic Sea floods the north of Laurasia. As a result, the climate is moistened, and vegetation forms in place of deserts.
Cretaceous period (Cretaceous). The final period of the Mesozoic era occupies a time period of 79 million years. Angiosperms appear. As a result of this, the evolution of fauna representatives begins. The movement of continents continues - Africa, America, India and Australia are moving away from each other. The continents of Laurasia and Gondwana begin to break up into continental blocks. Huge islands are forming in the south of the planet. The Atlantic Ocean is expanding. The Cretaceous period is a time of flourishing of flora and fauna on land. Due to evolution flora, fewer minerals end up in the seas and oceans. The amount of algae and bacteria in water bodies decreases.
Life of the Mesozoic Era
The diversity of plant life in the Mesozoic reaches its apogee. Many forms of reptiles developed, new larger and smaller species were formed. This is also the period of the appearance of the first mammals, which, however, could not yet compete with dinosaurs, and therefore remained in the rear positions in the food chain.
At the beginning of the Mesozoic, a very significant event occurred - the earth’s crust was cut by deep cracks. As before, these faults were channels for molten magma to reach the surface. When the violence of the earth's bowels ceased, the resulting deep depressions were filled with water.
The warm climate contributed to the rapid development of the biosphere.
Plants of the Mesozoic era
The increased humidity of the climate of the Jurassic period led to the rapid formation of plant matter on the planet. The forests consisted of ferns, conifers and cycads. Thujas and araucarias grew near the ponds. In the middle of the Mesozoic era, two vegetation belts formed:
- Northern, which was dominated by herbaceous ferns and gingkovic trees;
- Southern. Tree ferns and cycads reigned here.
In the modern world, ferns, cycads (palm trees reaching 18 meters in size) and cordaites of that time can be found in tropical and subtropical forests. Horsetails, mosses, cypresses and spruce trees had practically no differences from those that are common in our time.
Which was followed by . The Mesozoic Era is sometimes called the "Age of the Dinosaurs" because these animals were the dominant species throughout much of the Mesozoic.
After the Permian mass extinction wiped out more than 95% of ocean life and 70% of land species, a new Mesozoic era began about 250 million years ago. It consisted of the following three periods:
Triassic period, or Triassic (252-201 million years ago)
The first big changes were noticed in the type that dominated the Earth. Most of the flora that survived the Permian extinction were seed-bearing plants such as gymnosperms.
Cretaceous period, or Cretaceous (145-66 million years ago)
The last period of the Mesozoic was called the Cretaceous. The growth of flowering land plants occurred. They were helped by newly appeared bees and warm climatic conditions. Coniferous plants were still numerous during the Cretaceous.
In terms of Cretaceous marine animals, sharks and rays became commonplace. Survivors of the Permian extinction, such as starfish, were also abundant during the Cretaceous.
On land, the first small mammals began to develop during the Cretaceous period. First marsupials appeared, and then other mammals. Appeared more birds and there were more reptiles. The dominance of dinosaurs continued, and the number of carnivorous species increased.
At the end of the Cretaceous and Mesozoic, another thing happened. This disappearance is usually called K-T extinction(Cretaceous-Paleogene extinction). It destroyed all dinosaurs except birds and many other life forms on Earth.
There are different versions as to why the mass disappearance occurred. Most scientists agree that there was some kind of catastrophic event that caused this extinction. Various hypotheses include massive volcanic eruptions that released huge amounts of dust into the atmosphere, reducing the amount of sunlight reaching the Earth's surface and thereby causing the death of photosynthetic organisms such as plants and those that depended on them. Others believe that a meteorite fell to Earth and dust blocked the sunlight. Because the plants and animals that fed on them died out, this led to predators such as carnivorous dinosaurs also dying due to lack of food.
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Mesozoic era(248-65 million years ago) - the fourth era in the evolutionary process of life on our planet. Its duration is 183 million years. The Mesozoic era is divided into 3 periods: Triassic, Jurassic and Cretaceous.
Periods of the Mesozoic era
Triassic period (Triassic). The initial erathema of the Mesozoic era lasts 35 million years. This is the time of formation of the Atlantic Ocean. The single continent of Pangea again begins to break into two parts - Gondwana and Laurasia. Inland continental reservoirs are beginning to actively dry up. The depressions left from them are gradually filled with rock deposits. New mountain heights and volcanoes are appearing and exhibiting 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. The salt level in water bodies is rising. During this time period, representatives of birds, mammals and dinosaurs appear on the planet.
Jurassic period (Jura)- the most famous period of the Mesozoic era. It received its name due to the sedimentary deposits of that time found in the Jura (mountain ranges of Europe). The average period of the Mesozoic era lasts about 69 million years. The formation of modern continents begins - Africa, America, Antarctica, Australia. But they are not yet located in the order to which we are accustomed. Deep bays and small seas appear, separating the continents. Active formation of mountain ranges continues. The Arctic Sea floods the north of Laurasia. As a result, the climate is moistened, and vegetation forms in place of deserts.
Cretaceous period (Cretaceous). The final period of the Mesozoic era occupies a time period of 79 million years. Angiosperms appear. As a result of this, the evolution of fauna representatives begins. The movement of continents continues - Africa, America, India and Australia are moving away from each other. The continents of Laurasia and Gondwana begin to break up into continental blocks. Huge islands are forming in the south of the planet. The Atlantic Ocean is expanding. The Cretaceous period is the heyday of flora and fauna on land. Due to the evolution of the plant world, fewer minerals enter the seas and oceans. The amount of algae and bacteria in water bodies decreases.
In details periods of the Mesozoic era will be discussed in the following lectures.
Climate of the Mesozoic era
Climate of the Mesozoic era at the very beginning there was one on the entire planet. The air temperature at the equator and poles remained at the same level. At the end of the first period of the Mesozoic era, drought reigned on Earth for most of the year, which was briefly replaced by rainy seasons. But, despite the arid conditions, the climate became significantly colder than it was during the Paleozoic period. Some species of reptiles have fully adapted to cold weather. From these species of animals mammals and birds would later develop.
During the Cretaceous period it becomes even colder. All continents have their own climate. Tree-like plants appear, which lose their foliage during the cold season. Snow begins to fall at the North Pole.
Plants of the Mesozoic era
At the beginning of the Mesozoic, the continents were dominated by lycophytes, various ferns, the ancestors of modern palms, conifers and ginkgo trees. In the seas and oceans, the dominance belonged to algae that formed reefs.
The increased humidity of the climate of the Jurassic period led to the rapid formation of plant matter on the planet. The forests consisted of ferns, conifers and cycads. Thujas and araucarias grew near the ponds. In the middle of the Mesozoic era, two vegetation belts formed:
- Northern, which was dominated by herbaceous ferns and gingkovic trees;
- Southern. Tree ferns and cycads reigned here.
In the modern world, ferns, cycads (palm trees reaching 18 meters in size) and cordaites of that time can be found in tropical and subtropical forests. Horsetails, mosses, cypresses and spruce trees had practically no differences from those that are common in our time.
The Cretaceous period is characterized by the appearance of plants with flowers. In this regard, butterflies and bees appeared among insects, thanks to which flowering plants were able to quickly spread throughout the planet. Also at this time, ginkgo trees with leaves that fall off during the cold season begin to grow. Coniferous forests of this time period are very similar to modern ones. These include yews, firs and cypresses.
The development of higher gymnosperms lasts throughout the Mesozoic era. These representatives of the earth's flora got their name due to the fact that their seeds did not have an outer protective shell. The most widespread are cycads and bennettites. In appearance, cicadas resemble tree ferns or cycads. They have straight stems and massive leaves that look like feathers. Bennettites are trees or shrubs. They are similar in appearance to cycads, but their seeds are covered with a shell. This brings the plants closer to angiosperms.
Angiosperms appeared in the Cretaceous period. From this moment a new stage in the development of plant life begins. Angiosperms (flowering plants) are at the top rung of the evolutionary ladder. They have special reproductive organs - stamens and pistil, which are located in the flower cup. Their seeds, unlike gymnosperms, are hidden by a dense protective shell. These plants of the Mesozoic era quickly adapt to any climatic conditions and are actively developing. Behind short term Angiosperms began to dominate the entire Earth. Their various types and forms have reached modern world- eucalyptus, magnolia, quince, oleander, walnut trees, oak, birch, willow and beech. Of the gymnosperms of the Mesozoic era, we are now familiar only with coniferous species - fir, pine, sequoia 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 developed creatures formed, which gradually replaced the ancient species.
One of these types of reptiles was the animal-like pelycosaurs - sailing lizards. On their backs there was a huge sail, like a fan. They were replaced by therapsids, which were divided into 2 groups - predators and herbivores. Their legs were powerful and their tails were short. Therapsids were much superior to pelycosaurs in speed and endurance, but this did not save their species from extinction at the end of the Mesozoic era.
The evolutionary group of lizards from which mammals would later evolve are the cynodonts (dog teeth). These animals got their name due to their 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 cubs fed on their mother's milk.
At the beginning of the Mesozoic era it was formed the new kind lizards - archosaurs (ruling reptiles). They are the ancestors of all dinosaurs, pterosaurs, plesiosaurs, ichthyosaurs, placodonts and crocodylomorphs. Archosaurs, adapted to the climatic conditions on the coast, became predatory thecodonts. They hunted on land near bodies of water. Most thecodonts walked on 4 legs. But there were also individuals who ran on hind legs. In this way, these animals developed incredible speed. After some time, thecodonts evolved into dinosaurs.
By the end of the Triassic period, 2 species of reptiles predominated. Some are the ancestors of the crocodiles of our time. Others turned into dinosaurs.
Dinosaurs have a body structure that is not similar to other lizards. Their paws are located under the body. This feature allowed dinosaurs to move quickly. Their skin is covered with waterproof scales. Lizards move on 2 or 4 legs, depending on the species. The first representatives were fast coelophysis, powerful herrerasaurs and huge plateosaurs.
Besides dinosaurs, archosaurs gave rise to another species of reptile that was different from the rest. These are pterosaurs - the first lizards that can fly. They lived near bodies of water and ate various insects for food.
Animal world depths of the sea The Mesozoic era is also characterized by a diversity of species - ammonites, bivalves, families of sharks, bony and ray-finned fish. The most prominent predators were the underwater lizards that appeared not so long ago. Dolphin-like ichthyosaurs had high speed. One of the giant representatives of ichthyosaurs is Shonisaurus. Its length reached 23 meters, and its weight did not exceed 40 tons.
Lizard-like nothosaurs had sharp fangs. Placadonts, similar to modern newts, were searched for seabed shells of mollusks that were bitten with teeth. Tanystrophei lived on land. Long (2-3 times the body size), slender necks allowed them to catch fish while standing on the shore.
Another group of sea lizards of the Triassic period are plesiosaurs. At the beginning of the era, plesiosaurs reached a size of only 2 meters, and by the middle of the Mesozoic they evolved into giants.
The Jurassic period is the time of development of dinosaurs. The evolution of plant life gave impetus to the emergence different types herbivorous dinosaurs. And this, in turn, led to an increase in the number of predatory individuals. Some dinosaur species were the size of cats, while others were as large as giant whales. The most gigantic individuals are diplodocus and brachiosaurs, reaching a length of 30 meters. Their weight was about 50 tons.
Archeopteryx is the first creature standing on the border between lizards and birds. Archeopteryx did not yet know how to fly long distances. The beak was replaced by jaws with sharp teeth. The wings ended in fingers. Archeopteryx was the size of a modern crow. They lived mainly in forests and ate insects and various seeds.
In the middle of the Mesozoic era, pterosaurs were divided into 2 groups - pterodactyls and rhamphorhynchus. Pterodactyls lacked a 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 obtained food for themselves, and at night they hid in the trees. Pterodactyls ate fish, shellfish and insects. This group of pterosaurs had to jump from high places to take to the skies. Rhamphorhynchus also lived on the coast. They ate fish and insects. They had long tails, which had a blade 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 the depths of the sea was Liopleurodon, weighing 25 tons. Huge coral reefs were formed, in which ammonites, belemnites, sponges and sea mats settled. Representatives of the shark family and bony fishes are developing. New species of plesiosaurs and ichthyosaurs have appeared, sea turtles and crocodiles. Saltwater crocodiles developed flippers instead of legs. This feature allowed them to increase speed in the aquatic environment.
During the Cretaceous period of the Mesozoic era Bees and butterflies appeared. Insects carried pollen, and flowers gave them food. Thus began a long-term collaboration between insects and plants.
The most famous dinosaurs of the time were the predatory tyrannosaurs and tarbosaurs, the herbivorous bipedal iguanodons, the four-legged rhinoceros-like Triceratops and the small armored ankylosaurs.
Most mammals of that period belong to the subclass Allotheria. 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 occurs - the ancestors of modern animals separate from allotheria. They are divided into 3 species - oviparous, marsupial and placental. It is they who replace the dinosaurs at the beginning of the next era. Rodents and primates emerged from the placental species of mammals. Purgatorius became the first primates. The marsupial species gave rise to modern opossums, and the oviparous species gave rise to platypuses.
The airspace is dominated by early pterodactyls and new species of flying reptiles - Orcheopteryx and Quetzatcoatli. These were the most gigantic flying creatures in the entire history of the development of our planet. Together with representatives of pterosaurs, birds dominate the air. During the Cretaceous period, many ancestors of modern birds appeared - ducks, geese, loons. The length of the birds was 4-150 cm, weight - from 20 grams. up to several kilograms.
The seas were dominated by huge predators reaching 20 meters in length - ichthyosaurs, plesiosaurs and mososaurs. Plesiosaurs had a very long neck and a small head. Their large size did not allow them to develop high speed. The animals ate fish and shellfish. Mososaurs replaced saltwater crocodiles. These are giant predatory lizards with an aggressive character.
At the end of the Mesozoic era, snakes and lizards appeared, the species of which have reached the modern world unchanged. The turtles of this time period were also no different from those we see now. Their weight reached 2 tons, length - from 20 cm to 4 meters.
By the end of the Cretaceous period, most reptiles began to die out en masse.
Minerals of the Mesozoic era
Associated with the Mesozoic era a large number of deposits of natural resources. These are sulfur, phosphorites, polymetals, construction and combustible materials, oil and natural gas.
In Asia, due to 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 even during this period several large deposits brown and coal- Kansky 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 region and Moscow region.
Eona. The Mesozoic consists of three periods - Cretaceous, Jurassic and Triassic. The Mesozoic era lasted for 186 million years, starting 251 million years ago and ending 66 million years ago. To avoid getting confused about eons, eras and periods, use the geochronological scale, which is located, as a visual clue.
The lower and upper boundaries of the Mesozoic are defined by two mass extinctions. The lower limit is marked by the largest extinction in the history of the Earth - the Permian or Permian-Triassic, when about 90-96% of marine animals and 70% of terrestrial animals disappeared. The upper limit is marked by perhaps the most famous extinction event - the Cretaceous-Paleogene, when all the dinosaurs became extinct.
Periods of the Mesozoic era
1. or Triassic period. Lasted from 251 to 201 million years ago. The Triassic is known for the fact that during this period the mass extinction ends and the gradual restoration of the Earth's fauna begins. Also in the Triassic period, the largest supercontinent in history, Pangea, begins to break apart.
2. or Jurassic period. Lasted from 201 to 145 million years ago. Active development of plants, marine and terrestrial animals, giant dinosaurs and mammals.
3. or Cretaceous period. Lasted from 145 to 66 million years ago. The beginning of the Cretaceous period is characterized by the further development of flora and fauna. Large reptile dinosaurs reigned on the earth, some of which reached 20 meters in length and eight meters in height. The mass of some dinosaurs reached fifty tons. The first birds appeared in the Cretaceous period. At the end of the period, the Cretaceous disaster occurred. As a result of this disaster, many species of plants and animals disappeared. The biggest losses were among the dinosaurs. At the end of the period, ALL dinosaurs became extinct, including many gymnosperms, many aquatic reptiles, pterosaurs, ammonites, as well as from 30 to 50% of the species of all animal species that were able to survive.
Animals of the Mesozoic era
Apatosaurus
Archeopteryx
Askeptosaurus
Brachiosaurus
Diplodocus
Sauropods
Ichthyosaurs
Camarasaurus
Liopleurodon
Mastodonsaurus
Mosasaurs
Nothosaurs
Plesiosaurs
Sclerosaurus
Tarbosaurus
Tyrannosaurus
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On land, the diversity of reptiles increased. Their hind limbs have become more developed than their forelimbs. The ancestors of modern lizards and turtles also appeared in the Triassic period. In the Triassic period, the climate of certain territories was not only dry, but also cold. As a result of the struggle for existence and natural selection, the first mammals appeared from some predatory reptiles, which were no larger than rats. It is believed that they, like modern platypuses and echidnas, were oviparous.
Repentant in Jurassic period spread not only on land, but also in water and air. Flying lizards have become widespread. The Jurassic also saw the appearance of the very first birds, Archeopteryx. As a result of the flourishing of spore and gymnosperm plants, the body size of herbivorous reptiles increased excessively, some of them reaching a length of 20-25 m.
Plants
Thanks to the warm and humid climate, tree-like plants flourished during the Jurassic period. In the forests, as before, gymnosperms and fern-like plants dominated. Some of them, such as sequoia, have survived to this day. The first flowering plants that appeared in the Jurassic period had a primitive structure and were not widespread.
Climate
IN Cretaceous period The climate has changed dramatically. Cloudiness decreased significantly, and the atmosphere became dry and transparent. As a result, the sun's rays fell directly on the leaves of the plants. Material from the site
Animals
On land, the reptile class still retained its dominance. Predatory and herbivorous reptiles increased in size. Their bodies were covered with a shell. The birds had teeth, but were otherwise close to modern birds. In the second half of the Cretaceous period, representatives of the subclass of marsupials and placentals appeared.
Plants
Climatic changes in the Cretaceous period had a negative impact on ferns and gymnosperms, and their numbers began to decline. But angiosperms, on the contrary, multiplied. By the mid-Cretaceous, many families of monocotyledonous and dicotyledonous angiosperms had evolved. Due to its diversity and appearance they are in many ways close to modern flora.
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