Avian period of the Mesozoic. Life development in the Mesozoic era
The Mesozoic era is divided into three periods: Triassic, Jurassic and Cretaceous.
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 are taking place; land sharing contributed to speciation and other important evolutionary events. The climate was 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 came close to its current state.
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✪ The history of the development of life in the Mesozoic era. Part 1. Video lesson in biology grade 11
✪ Dinosaurs (tells paleontologist Vladimir Alifanov)
✪ Dinosaurs and other ancient animals (selection of ethers)
Subtitles
Geological periods
- triassic period (251.902 ± 0.024 - 201.3 ± 0.2)
- jurassic period (201.3 ± 0.2 - 145.0)
- cretaceous period (145.0 - 66.0).
Tectonics and paleogeography
Compared with the energetic mountain formation of the Late Paleozoic, Mesozoic tectonic deformations can be considered relatively soft. The main tectonic event was the breakup of the Pangea supercontinent into the northern part (Laurasia) and the southern (Gondwana). Later they broke up. In this case, the Atlantic Ocean was formed, surrounded mainly by the continental margins of the passive type (for example, the eastern coast of North America). The extensive transgressions that prevailed in the Mesozoic led to the appearance of numerous inland seas.
By the end of the Mesozoic, the continents almost took on a modern shape. Laurasia divided into Eurasia and North America, Gondwana into South America, Africa, Australia, Antarctica and the Indian subcontinent, the collision of which with the Asian continental plate caused intense orogenesis with the rise of the Himalayan mountains.
Africa
At the beginning of the Mesozoic era, Africa was still part of the Pangea supercontinent and had a relatively common fauna with it, which was dominated by theropods, prosauropods, and primitive poultry dinosaurs (towards the end of the Triassic).
Late Triassic fossils are found everywhere in Africa, but are more common in the south than in the north of the continent. As you know, the time line separating the Triassic from the Jurassic period was drawn according to a global catastrophe with the mass extinction of species (Triassic-Jurassic extinction), but the African layers of this time are still poorly understood.
Deposits of fossils of the early Jurassic period are distributed similarly to deposits of the Late Triassic, with more frequent outcrops in the south of the continent and a decreasing number of deposits in the north. During the Jurassic period, such iconic groups of dinosaurs as sauropods and ornithopods spread more and more throughout Africa. The paleontological layers of the mid-Jurassic in Africa are poorly represented and also poorly studied.
The Late Jurassic strata are also poorly represented here, with the exception of the impressive collection of Tendeguru Jurassic fauna in Tanzania, whose fossils are very similar to those found in the paleobiotic Morrison formation in western North America and belong to the same period.
In the middle of the Mesozoic, about 150-160 million years ago, Madagascar separated from Africa, while remaining connected with India and the rest of Gondwana. Among the fossils of Madagascar, abelizaurs and titanosaurs were discovered.
In the Early Cretaceous, part of the land that made up India and Madagascar separated from Gondwana. In the Late Cretaceous, the divergence of India and Madagascar began, continuing until the achievement of modern outlines.
Unlike Madagascar, mainland Africa was tectonically relatively stable throughout the Mesozoic. And, however, despite stability, significant changes occurred in its position relative to other continents as Pangea continued to disintegrate. By the beginning of the late Cretaceous, South America separated from Africa, thereby completing the formation of the Atlantic Ocean in its southern part. This event has had a huge impact on the global climate through changes in ocean currents.
In the Cretaceous period, Africa was inhabited by allosaurids and spinosaurids. The African theropod spinosaurus turned out to be one of the largest carnivores living on Earth. Among herbivores in the ancient ecosystems of those times, an important place was occupied by titanosaurs.
Deposits of fossils of the Cretaceous period are more common than deposits of the Jurassic, but often cannot be dated radiometrically, which makes it difficult to determine their exact age. Paleontologist Louis Jacobs, having spent enough time on field work in Malawi, argues that African fossil deposits "need more thorough excavation" and will necessarily be "fertile ... for scientific discoveries."
Climate
Over the past 1.1 billion years in Earth’s history, three successive cycles of the “ice age - warming”, called Wilson cycles, have been observed. Longer warm periods were characterized by a uniform climate, a large variety of flora and fauna, a predominance of carbonate precipitation and evaporites. Cold periods with glaciation at the poles were accompanied by a decrease in biodiversity, terrigenous and glacial precipitation. The cyclical process is considered to be the periodic process of connecting continents into a single continent (Pangea) and its subsequent decay.
The Mesozoic era is the warmest period in the Phanerozoic history of the Earth. It almost completely coincided with the period of global warming, which began in the Triassic period and ended already in the Cenozoic era with a small ice age, which continues to this day. For 180 million years, even in the polar regions, there was no stable ice cover. The climate was mostly warm and even, without significant temperature gradients, although climatic zonality existed in the northern hemisphere. A large amount of greenhouse gases in the atmosphere contributed to a uniform distribution of heat. The equatorial regions were characterized by a tropical climate (Tethys-Pantalassa region) with an average annual temperature of 25-30 ° С. Up to 45-50 ° N the subtropical region (Peritetis) extended, then a moderately warm boreal belt ran, and the circumpolar regions were characterized by a moderately cool climate.
The Mesozoic had a warm climate, mostly dry in the first half of the era and humid in the second. Slight cooling in the late Jurassic and the first half of the Cretaceous, strong warming in the middle of the Cretaceous (the so-called Cretaceous temperature maximum), at about the same time the equatorial climate zone appears.
Flora and fauna
Giant ferns, tree horsetails, and dies die out. Gymnosperms, especially conifers, flourish in the Triassic. In the Jurassic period, seed ferns die out and the first angiosperms appear (then represented only by tree forms), gradually spreading to all continents. This is due to a number of advantages - angiosperms have a highly developed conducting system, which ensures reliable cross-pollination, the embryo is supplied with food reserves (due to double fertilization, the triploid endosperm develops) and is protected by shells, etc.
In the animal kingdom, insects and reptiles flourish. Reptiles dominate and are represented by a large number of forms. In the Jurassic period, flying lizards appear and conquer the air. In the Cretaceous period, reptile specialization continues, they reach enormous size. The mass of some of the dinosaurs reached 50 tons.
The parallel evolution of flowering plants and pollinating insects begins. At the end of the Cretaceous period, cooling begins, the area of \u200b\u200bnear-water vegetation decreases. Herbivorous, predatory dinosaurs die out. Large reptiles are preserved only in the tropical zone (crocodiles). Due to the extinction of many reptiles, fast adaptive radiation of birds and mammals, which occupy vacant ecological niches, begins. In the seas, many forms of invertebrates and marine dinosaurs die out.
Birds, according to most paleontologists, are descended from one of the dinosaur groups. The complete separation of arterial and venous blood flow caused their warm-bloodedness. They spread widely overland and gave rise to many forms, including flightless giants.
The emergence of mammals is associated with a number of large aromorphoses that arose in one of the subclasses of reptiles. Aromorphoses: a highly developed nervous system, especially the cerebral cortex, providing adaptation to the conditions of existence by changing behavior, moving limbs from the sides under the body, the emergence of organs that ensure the development of the embryo in the mother’s body and subsequent feeding with milk, the appearance of a coat, the complete separation of blood circulation circles, the appearance of alveolar lungs, which increased the intensity of gas exchange and, as a result, the general level of metabolism.
Mammals appeared in the Triassic, but could not compete with dinosaurs and for 100 million years occupied a subordinate position in the ecological systems of that time.
: in 86 tons (82 tons and 4 extra). - SPb. , 1890-1907.
On land, the multiplicity of reptiles increased. The hind limbs have become more developed than the 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 from some predatory reptiles, the first mammals appeared, which were no more than rats. It is believed that they, like modern platypuses and echidna, were oviparous.
Plants
Presma penitent in jurassic spread not only on land, but also in water and air. Widespread flying dinosaurs. In the Jurassic period, the very first birds - archeopteryxes also appeared. As a result of the flowering of spore and gymnosperms, the body sizes of herbivorous reptiles excessively increased, some of them reaching a length of 20-25 m.
Plants
Thanks to the warm and humid climate, treelike plants flourished in the Jurassic. In the forests, as before, state gymnosperms and fern-like plants prevailed. Some of them, such as sequoia, have survived to the present. The first flowering plants that appeared in the Jurassic period had a primitive structure and were not widespread.
Climate
AT cretaceous the climate has changed dramatically. Cloudiness significantly decreased and the atmosphere became dry and transparent. As a result, the sun's rays fell directly on the leaves of plants. Material from the site
Animals
On land, the reptile class still maintained its dominance. Predatory and herbivorous reptiles increased in size. Their bodies were covered with shell. The birds had teeth, but otherwise they were close to modern birds. In the second half of the Cretaceous period, representatives of the subclass of marsupial and placental appeared.
Plants
Climatic changes in the Cretaceous period had a negative effect on fern-like and gymnosperms, and their numbers began to decrease. But angiosperms, on the contrary, multiplied. By the middle of the Cretaceous, many families of monocotyledonous and dicotyledonous angiosperms developed. In their diversity and appearance, they are largely close to the modern flora.
The Mesozoic era (the era of middle life) lasted about 175 million years and is divided into three periods: Triassic, Jurassic and Cretaceous.
Triassic . In the Triassic period, reptiles extremely developed, while not only terrestrial, but also adapted to life in water (ichthyosaurs, plesiosaurs) and air (pterosaurs). For the first time, dinosaurs, turtles, crocodiles and mammals appeared. Theriodonts began to die out gradually, their descendants had already appeared - the first mammals, which until the death of the dinosaurs would remain small, invisible creatures. Triassic was a period of archosaurs, who first led a water lifestyle, like modern crocodiles. Over time, their hind limbs survived. This gave them the opportunity to move to land, they began to move on their hind legs (massive tail served as a support). From them arose
the first two-legged dinosaurs. Dinosaurs - Meso-reptile fossils, which were the most numerous and diverse group of reptiles. Originated from pseudo-ear during the Triassic period, their heyday took place in the Jurassic period, and extinction - in the Cretaceous period of the Mesozoic era. The largest representatives reached a length of up to 30 m and a weight of up to 40-50 tons. In all dinosaurs, the chairman is relatively small, and the spinal cord formed a sacral thickening, larger in volume from the brain. The limbs were located under the body, which made it possible to increase to a huge size. The teeth grew from a separate hole, and not from the jaw bones, like other reptiles (such teeth were strong, and those teeth fell out, were quickly replaced by new ones). Dinosaurs reproduced by laying eggs. About 600 species of dinosaurs are known, which are divided into two rows. A series of lizards (theropod, or "zvonirogs") combined predatory bipeds (ceratosaurus, allosaurus, tyrannosaurs) and herbivorous tetrapods (brontosaurs, brachiosaurus, diplodocus) of dinosaurs. Row of pthotazovi (sauropods or "lizard-footed") were exclusively herbivorous forms, a number united bipedal (iguanodons, platypus) and four-legged (stegosaurs, ankylosaurs, triceratops) dinosaurs. So, dinosaurs and the first primitive mammals appear in the Triassic.
Yura . This period (duration of about 55 million years) was characterized by a warm, humid climate, which contributed to the rapid development of woody vegetation. Due to this, the growth of the roslinnoid sauropods occurred - the largest animals in the entire history of the Earth (brachiosaurus, apatosaurus, diplodocus), as well as herbivorous stegosaurs, which had a double row of plates along the spine. In the Jurassic, many bipedal theropod dinosaurs arose, such as the common Jurassic predators, allosaurus, megalosaurs, and ceratosaurus. At the end of the Jurassic period, birds appear. The first birds were Archeopteryx - the original fossil bird, had at the same time signs of birds and reptiles.
a piece of chalk . The name of the period (duration of about 65 Ma) is associated with the formation of chalk deposits from foraminifera shells. In the plant world of this period from gymnosperms arose angiosperms which is associated with such aromorphoses as: 1) the appearance of flower , which is the organ of sexual reproduction; 2) seed germ protection the walls of the ovary of the flower from adverse conditions; 3) the appearance of fetus , in which the seed is covered and protected by the pericarp; 4) double fertilization , which provides the formation of an embryo and a supply of nutrients; 5) conductive tissue improvement that improve the transport of substances throughout the plant. as a result of divergence, two classes of plants were formed in the angiosperms department: monocotyledonous and dicotyledonous, and as a result of idioadaptations in these classes various adaptations for pollination were developed. In chalk in the territory of modern North America and Asia, the platypus dinosaurs lived, as well as giant predatory dinosaurs, tyrannosaurs, one of the largest predators ever inhabited our planet. Horned Triceratops dinosaurs lived in the mountains of North America. In the animal world, the first placental mammals. They quickly became dominant among vertebrates. This was facilitated by the development of the nervous system, the occurrence of conditioned reflexes, concern for offspring, live births and feeding babies with milk. Due to the dry climate, the mass extinction of gymnosperms began, and since they were food for many reptiles, this also led to the extinction of reptiles.
So, during the Mesozoic era in the terrestrial ecosystems gymnosperms, reptiles and insects dominated, angiosperms, birds and mammals arose.
The Mesozoic era is a period in the geological history of the Earth from 251 million to 65 million years ago. It is at this stage in the history of the Earth that the formation of the main contours of modern continents and mountain building takes place. on the periphery of the Pacific, Atlantic and Indian oceans. Favorable climatic conditions and the separation of land contributed to important evolutionary events in the life of the biosphere - by the end of the Mesozoic, the bulk of the species diversity of Earth’s life approached its present state. Today we can judge the natural and climatic conditions, tectonic processes, the composition of the atmosphere, the animal and plant kingdoms of the Mesozoic era from a variety of geological evidence. As you know, the closer the current events to the modern period of history, the more interesting and extensive information about the past can be obtained from the geological record of the Earth.
If for the previous eras the basic data were obtained thanks to the study of the sediments of rocks of modern continents, then already for the second half of the Mesozoic and further, scientists have important indications for the seas and oceans. The Paleozoic era ended with the Hercynian folding stage. The folded systems formed in the Paleozoic on the site of the North Atlantic, Ural-Tien Shan and Mongol-Okhotsk geosynclines contributed to the connection of the northern platforms into a huge single massif - Laurasia. This continent stretches from the Rocky Mountains of North America to the Verkhoyansk Range in northeast Asia.
In the southern hemisphere, there was its own huge platform - the mainland of Gondwana, uniting South America, Antarctica, Africa, Hindustan and Australia. At a certain point in the history of the Earth, Laurasia and Gondwana constituted one whole - the supercontinent Pangea. But it was in the Mesozoic era that the gradual disintegration of Pangea and the formation of modern continents and oceans began. Therefore, the Mesozoic is often called a transition period in the development of the earth's crust, a real geological Middle Ages.
This era is best remembered as the era of dinosaurs. It lasted about half as long as the Paleozoic era, but was eventful. It was a time when plants, fish, mollusks, and especially reptiles, reached enormous sizes, as if everything on Earth was then on megavitamins. Dinosaurs were buried in giant ferns and huge trees, while pterosaurs (flying reptiles) cruised through the sky. Climatic conditions were warm everywhere.
Although geologists can only guess what forces led to the disintegration of the Pangea supercontinent into Laurasia and Gondvanu at that time, the example of the Antarctic suggests magmatic “hot spots” that caused faults around the globe. In some areas, dinosaurs and plants were isolated for millions of years and acquired special features, depending on their habitat, as well as local food and temperature conditions. Even small mammals began to fall under the feet of carnivorous dinosaurs, such as the Tyrannosaurus Rex, as an occasional snack.
During the Mesozoic era, more modern forms of insects, corals, marine organisms and flowering plants began to develop. Everything was really wonderful, when suddenly dinosaurs and many other animals became extinct. Many scientists believe that this was due to a collision with a large asteroid and the resulting smoky atmosphere in the following years, volcanic eruptions and mostly inclement weather. The sun could not break through the ashes and smoke, the water was polluted, and the Earth was certainly not a great resort.
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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 erathem of the Mesozoic era lasts 35 million years. This is the time of the formation of the Atlantic Ocean. The united continent of Pangea again begins to break into two parts - Gondwana and Laurasia. Inland continental reservoirs begin to dry up actively. The depressions left by them are gradually filled with sediment. New mountainous hills and volcanoes appear that show increased activity. The vast part of the land is also occupied by desert zones with weather conditions unsuitable for the life of most species of living creatures. The level of salt in the water rises. During this time period, representatives of birds, mammals and dinosaurs appear on the planet.
Jurassic period (Jura) - The most famous period of the Mesozoic era. It got its name thanks to sedimentary deposits of that time found in the Jura (European mountains). 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 we are used to. Deep gulfs and small seas appear that separate the continents. Active formation of mountain ranges continues. The Arctic Sea floods the north of Laurasia. As a result of this, the climate is moistened, and vegetation forms in the place of deserts.
Cretaceous (Chalk). The final period of the Mesozoic era occupies a time period of 79 million years. Angiosperms appear. As a result, the evolution of fauna begins. Continuation of the movement of the continents - Africa, America, India and Australia are moving away from each other. The continents of Laurasia and Gondwana begin to disintegrate into continental blocks. Huge islands form 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, less 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 considered in the following lectures.
Climate of the Mesozoic era
Climate of the Mesozoic era at the very beginning on the whole planet was one. The air temperature at the equator and the poles was kept at the same level. At the end of the first period of the Mesozoic era, drought reigned most of the year 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 cold weather. Mammals and birds will later come from these animal species.
In the Cretaceous period, it becomes even colder. All continents have their own climate. Tree-like plants appear that during the cold season lose their foliage. At the north pole, snow begins to fall.
Mesozoic era plants
At the beginning of the Mesozoic on the continents reunited, diverse ferns, ancestors of modern palm trees, conifers and ginkgo tree-like reigned reigned. In the seas and oceans, dominance belonged to algae forming reefs.
The increased humidity of the climate of the Jurassic led to the rapid formation of the plant mass of the planet. Forests consisted of ferns, conifers and cicadas. Thuja and araucaria grew near water bodies. In the middle of the Mesozoic era, two vegetation belts formed:
- Northern, dominated by herbaceous ferns and gingka trees;
- South. Tree-like ferns and cicadas reigned here.
In the modern world, ferns, cycads (palm trees reaching a size of 18 meters) and cordata of that time can be found in tropical and subtropical forests. Horsetails, crowns, cypresses and spruce practically had no differences from those that are common in our time.
The Cretaceous period is characterized by the appearance of plants having flowers. In this regard, butterflies and bees appeared among the insects, thanks to which flowering plants could quickly spread around the planet. Also at this time, ginkgo trees begin to grow with leaves falling 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 lasts throughout the Mesozoic era. These representatives of the terrestrial flora got their name due to the fact that their seeds did not have an outer protective shell. The most common are cicadas and bennettites. In appearance, cicadas are reminiscent of tree-like ferns or cypresses. They have straight stems and massive leaves, similar to feathers. Bennettites are trees or shrubs. Outwardly similar to cicadas, but their seeds are covered by a shell. This brings plants closer to angiosperms.
In the Cretaceous period, angiosperms appear. From this moment begins a new stage in the development of plant life. Angiosperms (flowering) are on the upper step of the evolutionary ladder. They have special reproductive organs - stamens and pestle, which are located in the flower bowl. Their seeds, unlike gymnosperms, are hidden by a dense protective shell. These plants of the Mesozoic era quickly adapt to any climatic conditions and actively develop. In a short time, angiosperms began to dominate the whole Earth. Their various types and forms have reached the modern world - eucalyptus trees, magnolias, quinces, oleanders, walnut trees, oaks, birches, willows and beeches. Of the gymnosperms of the Mesozoic era, only coniferous species are now familiar to us - fir, pine, sequoia and some others. The evolution of plant life of that period significantly overtook the development of representatives of the animal world.
Mesozoic era animals
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.
Pelicosaurus - sailing lizards, similar to animals, became one of these types of reptiles. On their backs was a huge fan-like sail. They were replaced by therapsids, which were divided into 2 groups - predators and herbivores. Their paws were powerful, their tails were short. In terms of speed and endurance, the therapsids were much superior to pelicosaurs, but this did not save their appearance from extinction at the end of the Mesozoic era.
The evolutionary group of lizards, from which mammals later derive, are cynodonts (dog teeth). These animals got their name due to powerful jaw bones and sharp teeth, with the help of which they could easily chew raw meat. Their bodies were covered with thick hair. Females laid eggs, but newborn babies ate breast 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 crocodilomorphs. Archosaurs, adapted to climatic conditions on the coast, became predatory thecodonts. They hunted on land near ponds. Most tecodonts walked on 4 legs. But there were individuals who ran on their hind legs. In this way, these animals developed an incredible speed. After some time, thecodonts evolved into dinosaurs.
By the end of the Triassic period, 2 species of reptiles prevailed. Some are the ancestors of crocodiles of our time. Others made dinosaurs.
The body structure dinosaurs are not similar 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 fast coelophysises, powerful herreosaurs and huge plateosaurs.
In addition to dinosaurs, archosaurs laid the foundation for another species of reptile, different from the rest. These are pterosaurs - the first pangolins that can fly. They lived near ponds, and ate various insects.
The fauna of the sea depths of the Mesozoic era is also characterized by a variety of species - ammonites, bivalves, shark families, bony and radiant fish. The most outstanding predators were the underwater dinosaurs that appeared not so long ago. Dolphin-like ichthyosaurs had a high speed. One of the giant representatives of ichthyosaurs is the shonizaur. Its length reached 23 meters, and the weight did not exceed 40 tons.
Lizard-like notosaurs had sharp fangs. Placadonts, similar to modern tritons, looked for shells of mollusks on the seabed, which were bitten by their teeth. Tanistrophies lived on land. Long (2-3 times exceeding body size), slender necks allowed them to fish, standing on the shore.
Another group of marine dinosaurs of the Triassic period are plesiosaurs. At the beginning of the era, plesiosaurs reached a size of only 2 meters, and by the middle of the Mesozoic evolved into giants.
The Jurassic period is the time of the development of dinosaurs. The evolution of plant life has given impetus to the emergence of different types of herbivorous dinosaurs. And this, in turn, led to an increase in the number of predatory individuals. Some species of dinosaurs were the size of a cat, while others were equal in size to giant whales. The most gigantic individuals are diplodocus and brachiosaurus, reaching a length of 30 meters. Their weight was about 50 tons.
Archeopteryx is the first creature standing on the border between lizards and birds. Archeopteryxes did not know how to fly long distances. The beak was replaced by jaws with sharp teeth. Wings ended with fingers. Archeopteryxes were the size of modern ravens. 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 ramforinha. Pterodactyls lacked tail and feathers. But there were big wings and a narrow skull with a few teeth. These creatures lived in packs on the coast. During the day they got their livelihood, and at night they hid in the trees. Pterodactyls were eaten by fish, shellfish, and insects. To rise into the sky, this group of pterosaurs had to jump from the hills. The ramforinhs 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 was convenient for catching slippery fish.
The most dangerous predator of the deep sea was lyopleurodon, weighing 25 tons. Huge coral reefs formed, in which ammonites, belemnites, sponges and marine mats settled. Representatives of the shark family and bone fish develop. New species of plesiosaurs and ichthyosaurs, sea turtles and crocodiles appeared. At sea crocodiles, fins formed instead of legs. This feature allowed them to increase speed in the aquatic environment.
In 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 of insects and plants.
The most famous dinosaurs of that time were predatory tyrannosaurs and tarbosaurs, herbivorous biped iguanodons, four-legged rhinoceros triceratops and small armored ankylosaurs.
Most mammals of that period belong to a subclass of allotherium. These are small animals similar to mice weighing no more than 0.5 kg. The only exceptional species are repenomoms. They grew 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 alloteria. They were divided into 3 types - egg-laying, marsupials and placental. It is they who, at the beginning of the next era, replace dinosaurs. From the placental species of mammals rodents and primates appeared. The first primates are purgatory. Modern opossums originated from the marsupial species, and oviparous spawned platypuses.
Early pterodactyls and new species of flying reptiles, orheopteryx and quetzcoatly, reign in the air. 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. In the Cretaceous period, many ancestors of modern birds appeared - ducks, geese, loons. The length of the birds was 4-150 cm, weight - from 20 g. up to several kilograms.
Enormous predators reigned in the seas, reaching a length of 20 meters - ichthyosaurs, plesiosaurs and mososaurs. Plesiosaurs had a very long neck and small head. Large sizes did not allow them to develop greater speed. The animals ate fish and shellfish. Mozosaurs replaced marine 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 without changing. Turtles of this time period also did not differ from those that we see now. Their weight reached 2 tons, length - from 20 cm to 4 meters.
By the end of the Cretaceous, most reptiles begin to die out en masse.
Minerals of the Mesozoic era
A large number of natural wealth deposits are associated with the Mesozoic era. These are sulfur, phosphorites, polymetals, construction and combustible materials, oil and natural gas.
In 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 even during this period several large deposits of brown and hard coal were formed - the Kansky basin, Bureinsky, Lensky.
Mesozoic oil and gas deposits are located in the Urals, Siberia, Yakutia, and the Sahara. Phosphorite deposits were found in the Volga region and the Moscow region.
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