Conditions of the inanimate nature of the Mesozoic era. Mesozoic era. Jurassic animals and plants
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 characteristics, is a temporary subdivision of the geochronological scale that lasted about one hundred and sixty million years.
General characteristics of the Mesozoic
During this huge time span, starting about 248 million years ago and ending 65 million years ago, the last supercontinent of 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 water and 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 stage, 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 into the marine environment unicellular algae, violated 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, marine life, 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 characteristic feature life in the Triassic was a combination of old biological species with new ones that had not yet gained strength. The time of conodonts and cephalopods with straight shells was ending; some six-rayed coral species have already begun to emerge and are yet to flourish; the first bony fish and sea \u200b\u200burchinsthat have a solid shell that does not decompose after death. Among terrestrial species, lepidodendrons, cordaites and treelike horsetails survived their long life. They were replaced by 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 movie, in which fiction is more than authentic. The truth is only in one thing - this is the flourishing of the power of the 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 replaced by bivalve molluscs, and primitive shells by oyster. Nowadays it is difficult to imagine the richness and splendor of the Jurassic forests, especially on the humid coasts. These are giant trees, fantastic ferns, extremely lush bush 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. 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. Basically, vegetable world at that distant time, it 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 origin of life on Earth took place about 3.8 billion years ago, when the formation of the earth's crust ended. Scientists have found that the first living organisms appeared in aquatic environment, and only a billion years later did the first creatures come to the surface of the land.
The formation of terrestrial flora was facilitated by the formation of organs and tissues in plants, the ability to reproduce by spores. Animals also evolved significantly and adapted to life on land: internal fertilization, the ability to lay eggs, pulmonary respiration appeared. An important stage in development was the formation of the brain, conditioned and unconditioned reflexes, survival instincts. Further evolution of animals provided the basis for the formation of humanity.
Dividing the history of the Earth into eras and periods gives an idea of \u200b\u200bthe peculiarities of the development of life on the planet at different time intervals. Scientists identify especially significant events in the formation of life on Earth in separate periods of time - eras, which are divided into periods.
There are five eras:
- Archean;
- proterozoic;
- paleozoic;
- mesozoic;
- cenozoic.
The Archean era began about 4.6 billion years ago, when the planet Earth was just beginning to form and there were no signs of life on it. The air contained chlorine, ammonia, hydrogen, the temperature reached 80 °, the radiation level exceeded the permissible limits, under such conditions the birth of life was impossible.
It is believed that about 4 billion years ago our planet collided with a celestial body, and the result was the formation of a satellite of the Earth - the Moon. This event became significant in the development of life, stabilized the axis of rotation of the planet, and contributed to the purification of water structures. As a result, the first life was born at the depths of the oceans and seas: protozoa, bacteria and cyanobacteria.
The Proterozoic era lasted from about 2.5 billion years to 540 million years ago. The remains of unicellular algae, molluscs, annelids were found. Soil begins to form.
The air at the beginning of the era was not yet saturated with oxygen, but in the process of vital activity the bacteria inhabiting the seas began to release more and more O 2 into the atmosphere. When the amount of oxygen was at a stable level, many creatures took a step in evolution and switched to aerobic breathing.
The Paleozoic era includes six periods.
Cambrian period (530 - 490 million years ago) is characterized by the emergence of representatives of all species of plants and animals. The oceans were inhabited by algae, arthropods, mollusks, and the first chordates (haikouichtis) appeared. The land remained uninhabited. The temperature remained high.
Ordovician period (490 - 442 million years ago). The first lichen settlements appeared on land, and the megalograpt (a representative of arthropods) began to go ashore to lay eggs. Vertebrates, coral, and sponges continue to develop in the ocean.
Silurian (442 - 418 million years ago). Plants emerge on land, and the rudiments of lung tissue form in arthropods. Education ends bone skeleton in vertebrates, sensory organs appear. Mountain building is in progress, different climatic zones are being formed.
Devonian (418 - 353 million years ago). The formation of the first forests, mainly ferns, is characteristic. Bone and cartilaginous organisms appear in water bodies, amphibians began to come out onto land, new organisms - insects - are formed.
Carboniferous period (353 - 290 million years ago). The emergence of amphibians, the subsidence of the continents occurs, at the end of the period there was a significant cooling, which led to the extinction of many species.
Permian period (290 - 248 million years ago). The earth is inhabited by reptiles, therapsids appeared - the ancestors of mammals. Hot climate led to the formation of deserts, where only hardy ferns and some conifers could survive.
The Mesozoic era is divided into 3 periods:
Triassic (248 - 200 million years ago). The development of gymnosperms, the appearance of the first mammals. Splitting the landmass into continents.
Jurassic period (200 - 140 million years ago). The emergence of angiosperms. The appearance of the ancestors of birds.
Cretaceous period (140 - 65 million years ago). Angiosperms (flowering) have become the dominant group of plants. The development of higher mammals, real birds.
The Cenozoic era consists of three periods:
Lower Tertiary or Paleogene (65 - 24 million years ago). The disappearance of most cephalopods, lemurs and primates appear, later parapithecus and dryopithecus. The development of the ancestors of modern mammalian species - rhinos, pigs, rabbits, etc.
Upper Tertiary or Neogene (24 - 2.6 million years ago). Mammals inhabit land, water, air. The emergence of Australopithecus - the first ancestors of humans. During this period, the Alps, Himalayas, and Andes were formed.
Quaternary period or anthropogen (2.6 million years ago - today). A significant event of the period is the appearance of man, first the Neanderthals, and soon Homo sapiens. Vegetable and animal world acquired modern features.
The Mesozoic era began about 250 million years ago and ended 65 million years ago. It lasted 185 million years. 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 is the Mesozoic - the time when real mammals, birds, flowering plants - the modern biosphere was actually 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.
In the Mesozoic, not only dinosaurs, but also other groups of reptiles, which are often mistakenly considered dinosaurs, arose - aquatic reptiles (ichthyosaurs and plesiosaurs), flying reptiles (pterosaurs), lepidosaurs - lizards, among which there were aquatic forms - mosasaurs. Snakes originated from lizards - they also appeared in the Mesozoic - the time of their occurrence is generally known, but paleontologists argue about whether this happened in water or on land.
Sharks flourished in the seas, and they lived in freshwater reservoirs. Mesozoic - the heyday of two groups of cephalopods - ammonites and belemnites. But in their shadows, the nautilus, which arose in the early Paleozoic and still exist, lived well, squids and octopuses familiar to us arose.
In the Mesozoic, modern mammals arose, first marsupials, and then placentals. In the Cretaceous period, groups of ungulates, insectivores, predators and primates have already emerged.
Interestingly, modern amphibians - frogs, toads and salamanders - also originated in the Mesozoic, presumably in the Jurassic period. So for all the antiquity of amphibians in general, modern amphibians are a relatively young group.
Throughout the Mesozoic, vertebrates tried to master a new environment for themselves - air. Reptiles were the first to fly - first small pterosaurs - rhamphorhynchia, then larger pterodactyls. Somewhere on the border of the Jurassic and Cretaceous, reptiles rose into the air - small feathered dinosaurs capable, if not of flight, then certainly of planning, and the descendants of reptiles - birds - enanciornis and real fan-tailed birds.
A real revolution in the biosphere took place with the advent of angiosperms - flowering plants. This led to an increase in the diversity of insects, which became flower pollinators. The gradual spread of flowering plants has changed the face of terrestrial ecosystems.
The Mesozoic ended with the famous mass extinction, better known as the "extinction of the dinosaurs." The reasons for this extinction are not clear, but the more we learn about the events that took place in the late Cretaceous, the less convincing the popular hypothesis of a meteorite catastrophe becomes. The biosphere of the Earth was changing and ecosystems of the Late Cretaceous were very different from those of the Jurassic period. A huge number of species became extinct throughout the Cretaceous period, and not at the end of it - but they simply did not survive the disaster. At the same time, there is evidence that in some places the typically Mesozoic fauna still existed at the very beginning of the next era - the Cenozoic. So while it is not possible to unequivocally answer the question of the reasons for the extinction that occurred at the end of the Mesozoic. It is only clear that if some kind of catastrophe happened, it only pushed the already begun changes
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Which I followed. The Mesozoic era is sometimes called the “era of the dinosaurs” because these animals were the dominant species for much of the Mesozoic.
After the massive Permian extinction wiped out more than 95% of ocean life and 70% of terrestrial 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 seen in the type that dominated the Earth. Most of the flora species that survived the Permian extinction became plants containing seeds, such as gymnosperms.
Cretaceous period, or chalk (145-66 million years ago)
The last period of the Mesozoic was called chalk. In there was a growth of flowering land plants. They were helped by the 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. Marsupials appeared first, and then other mammals. More birds appeared and became more reptiles... The dominance of dinosaurs continued, and the number of carnivorous species increased.
Another thing happened in the late Cretaceous and Mesozoic. This extinction is commonly referred to as the K-T extinction (Cretaceous-Paleogene extinction). It destroyed all dinosaurs except birds and many other life forms on Earth.
There are different versions as to why the mass disappearance occurred. Most scientists agree that it was some sort of catastrophic event that caused this extinction. Various hypotheses include massive volcanic eruptions that released huge amounts of dust into the atmosphere, which reduced the amount of sunlight reaching the Earth's surface and thereby caused the death of photosynthetic organisms such as plants and those who depended on them. Others believe that a meteorite fell to Earth, and the dust covered sunlight... As the plants and animals that fed on them became extinct, this led to the fact that predators such as carnivorous dinosaurs also died from lack of food.
The Mesozoic consists of three periods: triassic, Jurassic, Cretaceous.
In the triassic most of the land was above sea level, the climate was dry and warm. Due to the very dry climate in the Triassic, almost all amphibians disappeared. Therefore, the flowering of reptiles began, which were adapted to drought (Fig. 44). Among the plants in the Triassic, gymnosperms.
Figure: 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 rudiment of the third eye is preserved in lizards agamas and batbats.
Along with the undoubted progressive features in the organization of reptiles, there was one very significant imperfect feature - inconsistent body temperature. In the Triassic period, the first representatives of warm-blooded animals appeared - small primitive mammals - tricodonts. They originated from ancient animal-toothed lizards. But tricodonts the size of a rat could not compete with reptiles, so they did not spread widely.
Yura named after 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 neck.
In the Jurassic period appear different kinds insects and first birds - archeopteryx. Archeopteryx is about 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 them began to adapt to life in the water.
Pretty mild climate promoted the development of angiosperms.
a piece of 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 color, smell and nectar reserves.
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). Appearance similar to fish and 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 period, 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 pigeon were found, with the teeth of a lizard, which had lost the ability to fly.
Aromorphoses that contributed to the emergence of mammals.
1. Complication nervous system, the development of the cerebral cortex had an impact on 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 did the first mammals appear in the Mesozoic? 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 - Chalk).
1. Angiosperms.
2. Tricodonts.
4. Eucalyptus trees.
5. Archeopteryx.
6. Turtles.
7. Butterflies.
8. Brachiosaurus.
9. Hatteria.
11. Dinosaurs.