When did the Jurassic period begin and end? Encyclopedic short information about the Jurassic period. Geology as a science

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

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

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

Intense tectonic movements at the end of the Triassic and the beginning of the Jurassic periods contributed to the deepening of large bays, which gradually separated Africa and Australia from Gondwanaland. The gulf between Africa and America has deepened. Depressions formed in Eurasia: German, Anglo-Paris, West Siberian. The Arctic Sea flooded the northern coast of Laurasia.

Intense volcanism and mountain-building processes determined the formation of the Verkhoyansk fold system. The formation of the Andes and Cordillera continued. Warm sea currents 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. Very few deposits of dry climates are found: lagoonal gypsum, anhydrites, salts and red sandstones. The cold season already existed, but it was characterized only by a decrease in temperature. There was no snow or ice.

Climate Jurassic period depended not only on sunlight. Many volcanoes and outpourings of magma onto the bottom of the oceans heated the water and atmosphere, saturating the air with water vapor, which then rained onto the land, flowing in stormy streams into lakes and oceans. This is evidenced by numerous freshwater deposits: white sandstones alternating with dark loams.

The warm and humid climate favored the flourishing flora. Ferns, cycads, and conifers formed vast swampy forests. Araucarias, thujas, and cycads grew on the coast. Ferns and horsetails formed the undergrowth. In the Lower Jurassic, throughout the northern hemisphere, vegetation was quite monotonous. But starting from the Middle Jurassic, two plant zones can be identified: the northern, in which ginkgo and herbaceous ferns predominated, and the southern with bennetites, cycads, araucarias, and tree ferns.

The characteristic ferns of the Highland period were matonia, which are still preserved in the Malayan

archipelago. Horsetails and mosses were almost no different from modern ones. The place of extinct seed ferns and cordaites is taken by cycads, which still grow in tropical forests.

Ginkgo plants were also widespread. Their leaves turned edge-on to the sun and resembled huge fans. From North America and New Zealand to Asia and Europe, dense forests of coniferous plants - araucarias and bennetites - grew. The first cypress and possibly spruce trees appear.

Representatives of the Jurassic conifers also include sequoia - the modern giant California pine. Currently, redwoods remain only on the Pacific coast of North America. Some forms have been preserved. even more ancient plants, such as glassopteris. But there are few such plants, since they were replaced by more advanced ones.

The lush vegetation of the Jurassic period contributed to the widespread distribution of reptiles. Dinosaurs have evolved significantly. Among them, lizard-hatched and ornithischian are distinguished. Lizards moved on four legs, had five toes on their feet, and ate plants. Most of them had long neck, small head and long tail. They had two brains: one small one 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 Jurassic lakes and fed on aquatic vegetation. Every day, the brachiosaurus needed at least half a ton of green mass.

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

Brontosaurus was relatively tall, had 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. The brontosaurus lived in swamps and on the shores of lakes.

From 213 to 144 million years ago.
By the beginning of the Jurassic period, the giant supercontinent Pangea was in the process of active disintegration. There was still a single vast continent south of the equator, which was again called Gondwana. Subsequently, it also split into parts that formed today's Australia, India, Africa and South America. Terrestrial animals of the northern hemisphere could no longer move freely from one continent to another, but they still spread unhindered throughout the southern supercontinent.
At the beginning of the Jurassic period, the climate throughout the Earth was warm and dry. Then, as heavy rains began to soak the ancient Triassic deserts, the world became greener again, with more lush vegetation. The Jurassic landscape was thick with horsetails and club mosses, which had survived from the Triassic period. Palm-shaped bennettites are also preserved. In addition, there were many grios around. Vast forests of seed, common and tree ferns, as well as fern-like cycads, spread from bodies of water inland. Coniferous forests were still common. In addition to ginkgo and araucaria, the ancestors of modern cypresses, pines and mammoth trees grew in them.

Life in the seas.

As Pangea began to break apart, new seas and straits emerged, in which new types of animals and algae found refuge. Gradually, fresh sediment accumulated on the seabed. They are home to many invertebrates, such as sponges and bryozoans (sea mats). Other important events took place in the warm and shallow seas. Giant ones formed there Coral reefs, sheltering numerous ammonites and new varieties of belemnites (old relatives of today's octopuses and squids).
On land, in lakes and rivers, there lived many different types crocodiles, widely spread across the globe. There were also saltwater crocodiles with long snouts and sharp teeth for catching fish. Some of their varieties even grew flippers instead of legs to make swimming more convenient. Tail fins allowed them to develop in water higher speed than on land. New species of sea turtles have also appeared. Evolution also produced many species of plesiosaurs and ichthyosaurs, competing with new, fast-moving sharks and extremely agile bony fish.

This cycad is a living fossil. It is almost no different from its relatives that grew on Earth during the Jurassic period. Nowadays, cycads are found only in the tropics. However, 200 million years ago they were much more widespread.
Belemnites, living projectiles.

Belemnites were close relatives of modern cuttlefish and squid. They had a cigar-shaped internal skeleton. Its main part, consisting of calcareous substance, is called the rostrum. At the front end of the rostrum there was a cavity with a fragile multi-chambered shell that helped the animal stay afloat. This entire skeleton was placed inside the soft body of the animal and served as a solid frame to which its muscles were attached.
The solid rostrum is preserved in fossil form better than all other parts of the belemnite body, and it is usually the one that falls into the hands of scientists. But sometimes fossils without rostra are also found. The first such finds in early XIX V. have baffled many experts. They guessed that they were dealing with the remains of belemnites, but without the accompanying rostra these remains looked rather strange. The solution to this mystery turned out to be extremely simple, as soon as more data was collected about the feeding method of ichthyosaurs - the main enemies of belemnites. Apparently, the growthless fossils were formed when an ichthyosaur, having swallowed a whole school of belemnites, regurgitated the soft parts of one of the animals, while its hard internal skeleton remained in the stomach of the predator
Belemnites, like modern octopuses and squids, produced an inky liquid and used it to create a “smoke screen” when trying to escape from predators. Scientists have also discovered fossilized ink sacs of belemnites (organs in which a supply of ink liquid was stored). To one of the scientists victorian era, William Buckland, even managed to extract some ink from fossilized ink sacs, which he used to illustrate his book, The Bridgewater Treatise.

Plesiosaurs, barrel-shaped marine reptiles with four broad flippers that they used to row through the water like oars.
Glued fake.

No one has yet managed to find a complete fossil belemnite (soft part plus rostrum), although in the 70s. XX century in Germany a rather ingenious attempt was made to fool the whole scientific world with the help of skillful forgery. Whole fossils, allegedly obtained from one of the quarries in southern Germany, were purchased by several museums at very high prices before it was discovered that in all cases the limestone rostrum had been carefully glued to the fossilized soft parts of the belemnites!
This famous photograph, taken in 1934 in Scotland, was recently declared a fake. Nevertheless, for fifty years it fueled the enthusiasm of those who believed that the Loch Ness monster was a living plesiosaur.

Mary Anning (1799 - 1847) was only two years old when she discovered the first fossil skeleton of an ichthyosaur at Lyme Regis in Doroeth, England. Subsequently, she was lucky enough to also find the first fossil skeletons of a plesiosaur and pterosaur.
This child could find
Glasses, pins, nails.
But then we got in the way
Ichthyosaur bones.

Born for Speed

The first ichthyosaurs appeared in the Triassic. These reptiles were ideally adapted to life in the shallow seas of the Jurassic period. They had a streamlined body, fins of different sizes and long narrow jaws. The largest of them reached a length of about 8 m, but many species were no larger than a person. They were excellent swimmers, feeding mainly on fish, squid and nautiloids. Although ichthyosaurs were reptiles, their fossil remains suggest that they were viviparous, that is, they gave birth to ready-made offspring, like mammals. Perhaps ichthyosaur babies were born on the open sea, like whales.
Another group of predatory reptiles, also widespread in the Jurassic seas, are plesiosaurs. Their long-necked varieties lived near the surface of the sea. Here they hunted for schools of very large fish with the help of their flexible necks. Short-necked species, the so-called pliosaurs, preferred life at great depths. They ate ammonites and other mollusks. Some large pliosaurs apparently also hunted smaller plesiosaurs and ichthyosaurs.

Ichthyosaurs looked like exact copies dolphins, except for the shape of the tail and an extra pair of fins. For a long time scientists believed that all fossil ichthyosaurs they came across had a damaged tail. In the end, they realized that the spine of these animals had a curved shape and at its end there was a vertical tail fin (unlike the horizontal fins of dolphins and whales).
Life in the Jurassic air.

During the Jurassic period, insect evolution accelerated dramatically, and as a result, the Jurassic landscape eventually became filled with the endless buzzing and crackling sounds of many new species of insects crawling and flying everywhere. Among them were predecessors
modern ants, bees, earwigs, flies and wasps. Later, in the Cretaceous period, a new evolutionary explosion occurred when insects began to “establish contacts” with newly emerging flowering plants.
Until this time, real flying animals were found only among insects, although attempts to master the air environment were also observed in other creatures that learned to glide. Now whole hordes of pterosaurs have taken to the air. These were the first and largest flying vertebrates. Although the first pterosaurs appeared at the end of the Triassic, their true “takeoff” occurred precisely in the Jurassic period. The lung skeletons of pterosaurs consisted of hollow bones. The first pterosaurs had tails and teeth, but in more highly developed individuals these organs disappeared, which made it possible to significantly reduce their own weight. Some fossil pterosaurs have visible hair. Based on this, it can be assumed that they were warm-blooded.
Scientists still disagree about the lifestyle of pterosaurs. For example, it was originally believed that pterosaurs were a kind of “living gliders” that hovered, like vultures, above the ground in currents of rising hot air. Perhaps they even glided over the surface of the ocean, drawn sea ​​winds like modern albatrosses. However, some experts now believe that pterosaurs could flap their wings, that is, actively fly, like birds. Perhaps some of them even walked like birds, while others dragged their bodies along the ground or slept in the nesting areas of their relatives, hanging upside down, like bats.

Data obtained from the analysis of fossilized stomachs and droppings (coprolites) of ichthyosaurs indicate that their diet consisted mainly of fish and cephalopods(ammonites, nautiloids and squids). The contents of the stomachs of ichthyosaurs allowed us to make an even more interesting discovery. Small hard spines on the tentacles of squids and other cephalopods, apparently, caused ichthyosaurs a lot of inconvenience, since they were not digested and, accordingly, could not pass freely through them. digestive system. As a result, the thorns accumulated in the stomach, and from them scientists are able to find out what a given animal has eaten throughout its life. Thus, when studying the stomach of one of the fossil ichthyosaurs, it turned out that it swallowed at least 1,500 squids!
How birds learned to fly.

There are two main theories that try to explain how birds learned to fly. One of them claims that the first flights took place from the bottom up. According to this theory, it all started with bipedal animals, the predecessors of birds, running and jumping high into the air. Perhaps this is how they tried to escape from predators, or maybe they caught insects. Gradually, the feathered area of ​​the “wings” became larger, and the jumps, in turn, lengthened. The bird did not touch the ground longer and remained in the air. Add to this the flapping movements of their wings - and it will become clear to you how, after a long time, these “pioneers of aeronautics” learned to remain in flight for a long time, and their wings little by little acquired properties that allowed them to support their bodies in the air.
However, there is another theory, the opposite, according to which the first flights took place from top to bottom, from trees to the ground. Potential “flyers” had to first climb to a considerable height, and only then throw themselves into the air. In this case, the first step on the path to flight should have been planning, since with this type of movement the energy consumption is extremely insignificant - in any case, much less than with the “running-jumping” theory. The animal does not need to make additional efforts, because when gliding it is pulled down by the force of gravity.

The first fossil of Archeopteryx was discovered two years after the publication of Charles Darwin's book On the Origin of Species. This important discovery was further confirmation of Darwin's theory, which stated that evolution occurs very slowly and that one group of animals gives rise to another, undergoing a series of successive transformations. The famous scientist and close friend of Darwin, Thomas Huxley, predicted the existence of an animal similar to Archeopteryx in the past, even before its remains fell into the hands of scientists. In fact, Huxley described this animal in detail when it had not yet been discovered!
Step flight.

One scientist proposed an extremely interesting theory. It describes a series of stages through which the "pioneers of aeronautics" must have passed during the evolutionary process that eventually turned them into flying animals. According to this theory, once upon a time one of the groups of small reptiles, called pro-topbirds, switched to an arboreal lifestyle. Perhaps the reptiles climbed into the trees because it was safer there, or it was easier to get food, or it was more convenient to hide, sleep, or build nests. It was cooler in the treetops than on the ground, and these reptiles developed warm-bloodedness and feathers for better thermal insulation. Any extra long feathers on the limbs were useful - after all, they provided additional thermal insulation and increased the surface area of ​​the wing-shaped “arms”.
In turn, the soft, feathered forelimbs softened the impact on the ground when the animal lost its balance and fell from the ground. tall tree. They slowed down the fall (acting as a parachute), and also provided a more or less soft landing, serving as a natural shock absorber. Over time, these animals began to use feathered limbs as proto-wings. Further transition from para-
The transition from the gliding stage to the gliding stage should have been a completely natural evolutionary step, after which it was the turn of the last, flight, stage, which Archeopteryx almost certainly reached.

"Early" bird
The first birds appeared on Earth towards the end of the Jurassic period. The oldest of them, Archeopteryx, looked more like a small feathered dinosaur than a bird. She had teeth and a long, bony tail adorned with two rows of feathers. Three clawed fingers protruded from each of its wings. Some scientists believe that Archeopteryx used its clawed wings to climb trees, from where it periodically flew back to the ground. Others believe that he lifted himself off the ground using gusts of wind. In the process of evolution, bird skeletons became lighter, and toothed jaws were replaced by toothless beaks. They developed a wide sternum, to which powerful muscles necessary for flight were attached. All these changes made it possible to improve the structure of the bird’s body, giving it a structure optimal for flight.
The first fossil find of Archeopteryx was a single feather, discovered in 1861. Soon, a complete skeleton of this animal (with feathers!) was found in the same area. Since then, six fossilized skeletons of Archeopteryx have been discovered: some complete, others only fragmentary. The last such find dates back to 1988.

Age of dinosaurs.

The very first dinosaurs appeared more than 200 million years ago. Over the 140 million years of their existence, they have evolved into many different species. Dinosaurs spread across all continents and adapted to life in a wide variety of habitats, although none of them lived in burrows, climbed trees, flew or swam. Some dinosaurs were no larger than squirrels. Others weighed more than fifteen adult elephants combined. Some were swaying heavily on all fours. Others ran on two legs faster than Olympic champions in a sprint.
65 million years ago, all dinosaurs suddenly went extinct. However, before they disappeared from the face of our planet, they left us in the rocks a detailed “report” about their life and their time.
The most common group of dinosaurs in the Jurassic period were prosauropods. Some of them developed into the largest land animals of all time - sauropods ("lizard-footed"). These were the "giraffes" of the dinosaur world. They probably spent all their time eating leaves from the treetops. To provide vital energy to such a huge body, an incredible amount of food was required. Their stomachs were capacious digestive containers that continuously processed mountains of plant food.
Later, many varieties of small, fleet-footed dinos appeared.
saurs - the so-called hadrosaurs. These were the gazelles of the dinosaur world. They nibbled low-growing vegetation with their horny beaks and then chewed it with their strong molars.
The largest family of large carnivorous dinosaurs were the megalosaurids, or "huge lizards." The megalosaurid was a monster weighing a ton, with huge, sharp saw-like teeth with which it tore the flesh of its victims. Judging by some of the fossilized footprints, his toes were turned inward. It may have waddled around like a giant duck, swinging its tail from side to side. Megalosaurids inhabited all areas of the globe. Their fossil remains have been found in places as far apart as North America, Spain and Madagascar.
The early species of this family were, apparently, relatively small animals of fragile build. And later megalosaurids became truly bipedal monsters. Their hind legs ended in three toes armed powerful claws. Muscular forelimbs helped in hunting large plant-eating dinosaurs. The sharp claws undoubtedly left terrible lacerations in the side of the surprised victim. The powerful muscular neck of the predator allowed him to terrible force plunge dagger-shaped fangs deep into the body of the prey and tear out huge pieces of still warm meat.

In the Jurassic period, packs of Allosaurus roamed most of the earth's land. They, apparently, were a nightmarish sight: after all, each member of such a flock weighed more than a ton. Together, allosaurs could easily defeat even a large sauropod.

, conglomerates formed in a variety of conditions.

Jurassic System Division

Jurassic system is divided into 3 departments and 11 tiers:

system	Department	tier	Age, million years ago
Chalk	Lower	Berriasian	less
Yura	Upper (malm)	Titonian	152,1-145,0
		Kimmeridge	157,3-152,1
		Oxford	163,5-157,3
	Average (dogger)	Callovian	166,1-163,5
		Bathian	168,3-166,1
		Bayocian	170,3-168,3
		Aalensky	174,1-170,3
	Lower (lias)	Toarsky	182,7-174,1
		Pliensbachian	190,8-182,7
		Sinemyursky	199,3-190,8
		Hettangian	201,3-199,3
Triassic	Upper	Rhetic	more
Divisions are given according to IUGS as of April 2016

Geological events

213-145 million years ago, the single supercontinent Pangea began to break up into separate continental blocks. Shallow seas formed between them.

Climate

The climate in the Jurassic period was humid and warm (and by the end of the period - arid in the equator region).

Vegetation

During the Jurassic, vast areas were covered with lush vegetation, primarily diverse forests. They mainly consisted of ferns and gymnosperms.

Land animals

One of the fossil creatures that combines the characteristics of birds and reptiles is Archeopteryx, or the first bird. His skeleton was first discovered in the so-called lithographic shales in Germany. The discovery was made two years after the publication of Charles Darwin's work "On the Origin of Species" and became a strong argument in favor of the theory of evolution - it was initially considered transitional form from reptiles to birds (in fact, this was a dead-end branch of evolution, not directly related to real birds). Archeopteryx flew rather poorly (gliding from tree to tree), and was approximately the size of a crow. Instead of a beak, it had a pair of toothy, albeit weak, jaws. It had free fingers on its wings (of modern birds, only hoatzin chicks have them).

During the Jurassic period, small, furry, warm-blooded animals called mammals lived on Earth. They live next to dinosaurs and are almost invisible against their background. During the Jurassic period, the division of mammals into monotremes, marsupials and placentals occurred.

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Notes

Literature

• Iordansky N. N. Development of life on earth. - M.: Education, 1981.
• Karakash N. I. ,. Jurassic system and period // Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
• Koronovsky N.V., Khain V.E., Yasamanov N.A. Historical geology: Textbook. - M.: Academy, 2006.
• Ushakov S.A., Yasamanov N.A. Continental drift and climates of the Earth. - M.: Mysl, 1984.
• Yasamanov N.A. Ancient climates of the Earth. - L.: Gidrometeoizdat, 1985.
• Yasamanov N.A. Popular paleogeography. - M.: Mysl, 1985.

Links

• - Site about the Jurassic period, a large library of paleontological books and articles.

←	P A l e O h O th	Mesozoic (252.2-66.0 million years ago)			TO A th n O h O th	→
←		Triassic (252,2-201,3)	Jurassic period (201,3-145,0)	Cretaceous period (145,0-66,0)		→

An excerpt characterizing the Jurassic period

The trees stood bare and featureless, lazily moving their drooping, thorny branches. Further behind them stretched the joyless, burnt-out steppe, getting lost in the distance behind a wall of dirty, gray fog... Many gloomy, drooping human beings restlessly wandered back and forth, senselessly looking for something, not paying any attention to the world around them, which, and however, it did not evoke the slightest pleasure so that one would want to look at it... The whole landscape evoked horror and melancholy, seasoned with hopelessness...
“Oh, how scary it is here...” Stella whispered, shuddering. – No matter how many times I come here, I just can’t get used to it... How do these poor things live here?!
– Well, probably these “poor things” were too guilty once if they ended up here. No one sent them here - they just got what they deserved, right? – still not giving up, I said.
“But now you’ll look...” Stella whispered mysteriously.
A cave overgrown with grayish greenery suddenly appeared in front of us. And out of it, squinting, came a tall, stately man who in no way fit into this wretched, chilling scenery...
- Hello, Sad! – Stella greeted the stranger affectionately. - I brought my friend! She doesn't believe that good people can be found here. And I wanted to show you to her... You don’t mind, do you?
“Hello, dear...” the man answered sadly, “But I’m not that good to show off to anyone.” You're wrong...
Oddly enough, I actually immediately liked this sad man for some reason. He exuded strength and warmth, and it was very pleasant to be around him. In any case, he was in no way like those weak-willed, grief-stricken people who surrendered to the mercy of fate, with whom this “floor” was chock-full.
“Tell us your story, sad man...” Stella asked with a bright smile.
“There’s nothing to tell, and there’s nothing particularly to be proud of...” the stranger shook his head. - And what do you need this for?
For some reason, I felt very sorry for him... Without knowing anything about him, I was already almost sure that this man could not have done anything truly bad. Well, I just couldn’t!.. Stela, smiling, followed my thoughts, which she apparently really liked...
“Well, okay, I agree - you’re right!..” Seeing her happy face, I finally honestly admitted.
“But you don’t know anything about him yet, but with him everything is not so simple,” Stella said, smiling slyly and contentedly. - Well, please tell her, Sad...
The man smiled sadly at us and said quietly:
– I’m here because I killed... I killed many. But it was not out of desire, but out of need...
I was immediately terribly upset - he killed!.. And I, stupid, believed it!.. But for some reason I stubbornly did not have the slightest feeling of rejection or hostility. I clearly liked the person, and no matter how hard I tried, I couldn’t do anything about it...
- Is it really the same guilt - to kill at will or out of necessity? – I asked. – Sometimes people have no choice, do they? For example: when they have to defend themselves or protect others. I have always admired heroes - warriors, knights. I generally always adored the latter... Is it possible to compare simple murderers with them?
He looked at me for a long time and sadly, and then also quietly answered:
- I don’t know, dear... The fact that I am here says that the guilt is the same... But the way I feel this guilt in my heart, then no... I never wanted to kill, I just defended my land, I was a hero there... But here it turned out that I was just killing... Is this right? I think no...
- So you were a warrior? – I asked hopefully. - But then, this is a big difference– you defended your home, your family, your children! And you don’t look like a murderer!..
- Well, we are all not like the way others see us... Because they see only what they want to see... or only what we want to show them... And about the war - I also first just as you thought, you were even proud... But here it turned out that there was nothing to be proud of. Murder is murder, and it doesn’t matter how it was committed.
“But this is not right!..” I was indignant. - What happens then - a maniac-killer turns out to be the same as a hero?!.. This simply cannot be, this should not happen!
Everything inside me was raging with indignation! And the man sadly looked at me with his sad, gray eyes, in which understanding was read...
“A hero and a murderer take lives in the same way.” Only, probably, there are “extenuating circumstances,” since a person protecting someone, even if he takes a life, does so for a bright and righteous reason. But, one way or another, they both have to pay for it... And it’s very bitter to pay, believe me...
– Can I ask you how long ago you lived? – I asked, a little embarrassed.
- Oh, quite a long time ago... This is the second time I’m here... For some reason, my two lives were similar - in both of them I fought for someone... Well, and then I paid... And it’s always just as bitter ... – the stranger fell silent for a long time, as if not wanting to talk about it anymore, but then he quietly continued. – There are people who love to fight. I always hated it. But for some reason, life is returning me to the same circle for the second time, as if I was locked in this, not allowing me to free myself... When I lived, all our peoples fought among themselves... Some seized foreign lands - others they defended the lands. Sons overthrew fathers, brothers killed brothers... Anything happened. Someone accomplished unimaginable feats, someone betrayed someone, and someone turned out to be simply a coward. But none of them even suspected how bitter the payment would be for everything they had done in that life...
– Did you have family there? – to change the subject, I asked. - Were there children?
- Certainly! But that was already so long ago!.. They once became great-grandfathers, then they died... And some are already living again. That was a long time ago...
“And you’re still here?!..” I whispered, looking around in horror.
I couldn’t even imagine that he had been existing here like this for many, many years, suffering and “paying” his guilt, without any hope of leaving this terrifying “floor” even before the time came for him to return to physical Earth!.. And there he will again have to start all over again, so that later, when his next “physical” life ends, he will return (perhaps here!) with a whole new “baggage”, bad or good, depending on how he will live his “next” earthly life... And he could not have any hope of freeing himself from this vicious circle (be it good or bad), since, having begun his earthly life, each person “dooms” himself to this endless, eternal a circular “journey”... And, depending on his actions, returning to the “floors” can be very pleasant, or very scary...

The Jurassic period is the middle Mesozoic era. This piece of history is primarily famous for its dinosaurs; it was a very good time for all living things. During the Jurassic period, for the first time, reptiles dominated everywhere: in water, on land and in the air.
This period was named after a mountain range in Europe. The Jurassic period began about 208 million years ago. This period was more revolutionary than the Triassic. This revolutionism was with those things that happened to the earth's crust, because it was during the Jurassic period that the continent of Pangea began to diverge. Since that time the climate has become warmer and more humid. In addition, the water level in the world's oceans began to rise. All this provided great opportunities for animals. Due to the fact that the climate became more favorable, plants began to appear on land. And corals began to appear in shallow waters.

The Jurassic period lasted from 213 to 144 million years ago. At the very beginning of the Jurassic period, the climate throughout the Earth was dry and warm. All around were deserts. But later they began to be saturated with moisture by heavy rains. And the world became greener, lush vegetation began to bloom.
Ferns, conifers and cycads formed vast swampy forests. Araucarias, thujas, and cycads grew on the coast. Ferns and horsetails formed extensive forested areas. At the beginning of the Jurassic period, about 195 million years ago. Throughout the northern hemisphere, the vegetation was quite monotonous. But already starting from the middle of the Jurassic period, about 170-165 million years ago, two (conditional) plant belts were formed: northern and southern. The northern plant belt was dominated by ginkgo and herbaceous ferns. During the Jurassic period, ginkgos were very widespread. Groves of ginkgo trees grew throughout the belt.

The southern plant belt was dominated by cycads and tree ferns.
Ferns from the Jurassic period survive today in some parts of the wild. Horsetails and mosses were almost no different from modern ones. The habitats of ferns and cordaites of the Jurassic period are now occupied by tropical forests, consisting mainly of cycads. Cycads are a class of gymnosperms that dominated the green cover of the Jurassic Earth. Nowadays they are found here and there in the tropics and subtropics. Dinosaurs roamed under the shade of these trees. Externally, cycads are so similar to low (up to 10-18 m) palm trees that they were even initially identified as palm trees in the plant system.

In the Jurassic period, ginkgos were also common - deciduous (which is unusual for gymnosperms) trees with an oak-like crown and small fan-shaped leaves. Only one species has survived to this day - Ginkgo biloba. The first cypress and, possibly, spruce trees appear precisely during the brisk period. Coniferous forests of the Jurassic period were similar to modern ones.

During the Jurassic period, temperate climate. Even arid zones were rich in vegetation. Such conditions were ideal for the reproduction of dinosaurs. Among them are the lizard and ornithischians.

Lizards moved on four legs, had five toes on their feet, and ate plants. Most of them had a long neck, small head and long tail. They had two brains: one small one in the head; the second is much larger in size - at the base of the tail.
The largest of Jurassic dinosaurs there was a brachiosaurus that reached a length of 26 m and weighed about 50 tons. It had columnar legs, a small head, and a thick long neck. Brachiosaurs lived on the shores of Jurassic lakes and fed on aquatic vegetation. Every day, the brachiosaurus needed at least half a ton of green mass.
Diplodocus is the oldest reptile, its length was 28 m. It had a long thin neck and a long thick tail. Like a brachiosaurus, Diplodocus walked on four legs, the hind legs being longer than the front ones. Diplodocus spent most of its life in swamps and lakes, where it grazed and escaped from predators.

Brontosaurus was relatively tall, had a large hump on its back and a thick tail. Chisel-shaped small teeth were densely located on the jaws of the small head. The brontosaurus lived in swamps and on the shores of lakes. Brontosaurus weighed about 30 tons and was over 20 in length. Lizard-footed dinosaurs (sauropods) were the largest land animals known so far. All of them were herbivores. Until recently, paleontologists believed that such heavy creatures were forced to carry out most your life in the water. It was believed that on land his shin bones would “break” under the weight of the colossal carcass. However, findings of recent years (in particular, leg fragments) indicate that sauropods preferred to wander in shallow water; they also entered solid ground. Relative to body size, brontosaurs had an extremely small brain, weighing no more than a pound. In the area of ​​the sacral vertebrae of the Brontosaurus there was an expansion of the spinal cord. Being much larger than the brain, it controlled the muscles of the hind limbs and tail.

Ornithischian dinosaurs are divided into bipeds and quadrupeds. Different in size and appearance, they fed mainly on vegetation, but predators also appeared among them.

Stegosaurs are herbivores. Stegosaurs are especially abundant in North America, where several species of these animals are known, reaching a length of 6 m. The back was steeply convex, the height of the animal reached 2.5 m. The body was massive, although the stegosaurus moved on four legs, its forelimbs were much shorter rear On the back there were large bone plates in two rows that protected the spinal column. At the end of the short, thick tail, used by the animal for protection, there were two pairs of sharp spines. Stegosaurus was a vegetarian and had an exceptionally small head and correspondingly tiny brain, little more than walnut. Interestingly, the expansion of the spinal cord in the sacral region, associated with the innervation of the powerful hind limbs, was much larger in diameter than the brain.
Many scaly lepidosaurs appear - small predators with beak-shaped jaws.

Flying lizards first appeared in the Jurassic period. They flew using 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 tube-shaped bones. The extremely elongated outer fifth digit 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, rarely three bones and had claws. The hind limbs were quite developed. There were sharp claws at their ends. The skull of flying lizards was relatively large, usually elongated and pointed. In old lizards, the cranial bones fused and the skulls became similar to the skulls of birds. The premaxillary bone sometimes grew into an elongated toothless beak. Toothed lizards had simple teeth and sat in recesses. The largest teeth were in the front. Sometimes they stuck out to the side. This helped the lizards catch and hold prey. The spine of animals consisted of 8 cervical, 10-15 dorsal, 4-10 sacral and 10-40 caudal vertebrae. The chest was wide and had a high keel. The shoulder blades were long pelvic bones have grown together. The most typical representatives of flying lizards are pterodactyl and rhamphorhynchus.

Pterodactyls were in most cases tailless, varying in size - from the size of a sparrow to a crow. They had wide wings and a narrow skull elongated forward with a small number of 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 rocks. The skin of pterodactyls was wrinkled and bare. They ate mainly fish, sometimes sea lilies, mollusks, and insects. In order to fly, pterodactyls were forced to jump from cliffs or trees.
Rhamphorhynchus had long tails, long narrow wings, a large skull with numerous teeth. Long teeth of varying sizes curved forward. The lizard's tail ended in a blade that served as a rudder. Rhamphorhynchus could take off from the ground. They settled on the banks of rivers, lakes and seas, feeding on insects and fish.

Flying lizards lived only in the Mesozoic era, and their heyday occurred in the Late Jurassic period. Their ancestors were, apparently, extinct ancient reptiles pseudosuchians. Long-tailed forms appeared earlier than short-tailed ones. At the end of the Jurassic period they became extinct.
It should be noted that flying lizards were not the ancestors of birds and bats. Flying lizards, birds and the bats each originated and developed in its own way, and there are no close family ties between them. The only thing they have in common is the ability to fly. And although they all acquired this ability due to changes in the 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 bone plates. The elbow, metatarsus, hand and fingers differed little from each other in shape. About a hundred bone plates supported the 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. Appearing in the Middle Triassic, they reached their peak already in the Lower Jurassic; in the Cretaceous they were common in all seas. They were divided into two main groups: long-necked with a small head (plesiosaurs proper) and short-necked with a rather massive head (pliosaurs). The limbs turned into powerful flippers, which became the main organ of swimming. More primitive Jurassic pliosaurs come mainly from Europe. A plesiosaur from the Lower Jurassic reached a length of 3 m. These animals often went ashore to rest. Plesiosaurs were not as agile in water as pliosaurs. This deficiency was to a certain extent compensated for by the development of a long and very flexible neck, with the help of which plesiosaurs could grab prey with lightning speed. They ate mainly fish and shellfish.
During 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.

There were a lot of fish in the Jurassic seas: bony fish, stingrays, sharks, cartilaginous fish, and ganoid fish. They had an internal skeleton made of flexible cartilaginous tissue impregnated with calcium salts: a dense bony scaly covering that protected them well from enemies, and jaws with strong teeth.
Among the invertebrates in the Jurassic seas, there were ammonites, belemnites, and crinoids. However, in the Jurassic period there were much fewer ammonites than in the Triassic. Jurassic ammonites differ from Triassic ammonites in their structure, with the exception of phyloceras, which did not change at all during the transition from the Triassic to the Jurassic. Certain groups of ammonites have preserved mother-of-pearl to this day. Some animals lived in the open sea, others inhabited bays and shallow inland seas.

Cephalopods - belemnites - swam in whole schools in the Jurassic seas. Along with small specimens, there were real giants - up to 3 m long.
Remains of belemnite internal shells, known as “devil's fingers,” are found in Jurassic sediments.
In the seas of the Jurassic period, bivalves also developed significantly, especially those belonging to the oyster family. They begin to form oyster banks. Significant changes are undergoing sea ​​urchins, settled on the reefs. Along with the round forms that have survived to this day, there lived bilaterally symmetrical, irregularly shaped hedgehogs. Their body was stretched in one direction. Some of them had a jaw apparatus.

The Jurassic seas were relatively shallow. Rivers brought muddy water into them, delaying gas exchange. The deep bays were filled with rotting remains and silt containing, a large number of hydrogen sulfide. That is why in such places the remains of animals brought in are well preserved. sea ​​currents or waves.
Many crustaceans appear: barnacles, decapods, phyllopods, freshwater sponges, among insects - dragonflies, beetles, cicadas, bugs.

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



According to modern ideas of scientists, the geological history of our planet is 4.5-5 billion years. In the process of its development, it is customary to distinguish geological periods of the Earth.

general information

The geological periods of the Earth (the table below) represent the sequence of events that occurred during the development of the planet from the moment of its formation earth's crust. Over time, on the surface there are various processes, such as the emergence and destruction of land areas submerged under water and their uplift, glaciation, as well as the appearance and disappearance of various species of plants and animals, etc. Our planet bears clear traces of its formation. Scientists claim that they are able to record them with mathematical accuracy in different layers of rocks.

Main groups of sediments

Geologists, trying to reconstruct the history of the planet, study rock layers. It is customary to divide these deposits into five main groups, highlighting the following geological eras Earth: ancient (Archaean), early (Proterozoic), ancient (Paleozoic), middle (Mesozoic) and new (Cenozoic). It is believed that the border between them runs along the largest evolutionary phenomena that occurred on our planet. The last three eras, in turn, are divided into periods, since the remains of plants and animals are most clearly preserved in these deposits. Each stage is characterized by events that had a decisive influence on the current topography of the Earth.

The oldest stage

The Earth was characterized by rather violent volcanic processes, as a result of which igneous granite rocks appeared on the surface of the planet - the basis for the formation of continental plates. At that time, only microorganisms existed here that could do without oxygen. It is assumed that the deposits of the Archean era cover individual areas of the continents with an almost complete shield; they contain a lot of iron, silver, platinum, gold and ores of other metals.

Early stage

It is also characterized by high volcanic activity. During this period, the mountain ranges of the so-called Baikal fold were formed. They have practically not survived to this day; today they represent only isolated insignificant rises on the plains. During this period, the Earth was inhabited by simple microorganisms and blue-green algae, and the first multicellular organisms appeared. The Proterozoic rock layer is rich in minerals: mica, non-ferrous metal ores and iron ores.

Ancient stage

The first period of the Paleozoic era was marked by the formation of mountain ranges. This led to a significant reduction in sea basins, as well as the emergence of huge areas of land. Individual ridges of that period have survived to this day: in the Urals, Arabia, Southeast China and Central Europe. All these mountains are “worn out” and low. The second half of the Paleozoic is also characterized by mountain-building processes. Ranges were formed here. This era was more powerful, vast mountain ranges arose in the territories of the Urals and Western Siberia, Manchuria and Mongolia, Central Europe, as well as Australia and North America. Today they are represented by very low blocky massifs. Animals of the Paleozoic era are reptiles and amphibians, the seas and oceans are inhabited by fish. Algae predominated among the flora. Palaeozoic It is characterized by large deposits of coal and oil that arose during this era.

Middle stage

The beginning of the Mesozoic era is characterized by a period of relative calm and gradual destruction mountain systems, created earlier, submersion of lowland areas (part of Western Siberia). The second half of this period was marked by the formation of the Mesozoic folding ridges. Very vast mountainous countries appeared, which still have the same appearance today. Examples include the mountains of Eastern Siberia, the Cordillera, and certain areas of Indochina and Tibet. The earth was densely covered with lush vegetation, which gradually died and rotted. Thanks to the hot and humid climate, the active formation of peat bogs and swamps took place. This was the era of giant lizards - dinosaurs. The inhabitants of the Mesozoic era (herbivores and predators) spread throughout the entire planet. At the same time, the first mammals appeared.

New stage

The Cenozoic era, which replaced the middle stage, continues to this day. The beginning of this period was marked by an increase in the activity of the internal forces of the planet, which led to a general uplift of huge areas of land. This era is characterized by the emergence of mountain ranges within the Alpine-Himalayan belt. During this period, the Eurasian continent acquired its modern shape. In addition, there was a significant rejuvenation of the ancient massifs of the Urals, Tien Shan, Appalachians and Altai. The climate on Earth changed sharply, and periods of powerful ice sheets began. The movements of glacial masses changed the topography of the continents. As a result, hilly plains with a huge number of lakes were formed. Animals Cenozoic era- these are mammals, reptiles and amphibians, many representatives of the initial periods have survived to this day, others have become extinct (mammoths, woolly rhinoceroses, saber-toothed tigers, cave bears and others) for one reason or another.

What is a geological period?

The geological stage as a unit of our planet is usually divided into periods. Let's see what the encyclopedia says about this term. A period (geological) is a major interval of geological time during which rocks were formed. In turn, it is subdivided into smaller units, which are commonly called epochs.

The first stages (Archean and Proterozoic) in connection with complete absence or an insignificant amount of animal and plant deposits in them, it is not customary to divide them into additional areas. The Paleozoic era includes the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian periods. This stage is characterized the largest number subintervals, the rest were limited to only three. The Mesozoic era includes the Triassic, Jurassic and Cretaceous stages. The Cenozoic era, the periods of which are the most studied, is represented by the Paleogene, Neogene and Quaternary subinterval. Let's take a closer look at some of them.

Triassic

The Triassic period is the first subinterval of the Mesozoic era. Its duration was about 50 million years (beginning 251-199 million years ago). It is characterized by renewal of marine and terrestrial fauna. At the same time, a few representatives of the Paleozoic continue to exist, such as spiriferids, tabulates, some elasmobranchs, etc. Among invertebrates, ammonites are very numerous, giving rise to many new forms important for stratigraphy. Among corals, six-rayed forms predominate, among brachiopods - terebratulides and rhynchonelids, and in the group of echinoderms - sea urchins. Vertebrates are mainly represented by reptiles - large lizard-hipped dinosaurs. Thecodonts are widely distributed - fast-moving land reptiles. Besides, in Triassic appear first large inhabitants aquatic environment- ichthyosaurs and plesiosaurs, but they reached their peak only in the Jurassic period. Also at this time, the first mammals arose, which were represented by small forms.

Flora during the Triassic (geological) period loses Paleozoic elements and acquires an exclusively Mesozoic composition. Fern plant species, sago, conifers and ginkgos predominate here. Climatic conditions characterized by significant warming. This leads to drying out of many inland seas, and in the remaining ones the level of salinity increases significantly. In addition, the areas of inland water bodies are greatly reduced, resulting in the development of desert landscapes. For example, the Tauride formation of the Crimean Peninsula belongs to this period.

Yura

The Jurassic period gets its name from the Jurassic Mountains in Western Europe. It constitutes the middle part of the Mesozoic and most closely reflects the main features of the development of organic matter of this era. In turn, it is usually divided into three sections: lower, middle and upper.

The fauna of this period is represented by widespread invertebrates - cephalopods (ammonites, represented by numerous species and genera). In terms of sculpture and the nature of their shells, they differ sharply from the representatives of the Triassic. In addition, during the Jurassic period, another group of mollusks flourished - belemnites. At this time, six-rayed reef-building corals, lilies and urchins, as well as numerous elasmobranchs, reach significant development. But the Paleozoic brachiopod species completely disappear. Marine fauna vertebrate species differs significantly from the Triassic, it reaches enormous diversity. During the Jurassic period, fish, as well as aquatic reptiles - ichthyosaurs and plesiosaurs, were widely developed. At this time, the transition from land and adaptation to marine environment crocodiles and turtles. Huge variety reach various types of terrestrial vertebrates - reptiles. Among them, dinosaurs come to their heyday, which are represented by herbivores, predators and other forms. Most of them reach 23 meters in length, for example, Diplodocus. In the deposits of this period, a new species of reptile is found - flying lizards, which are called "pterodactyls". At the same time, the first birds appear. The Jurassic flora reaches a lush flourishing: gymnosperms, ginkgos, cycads, conifers (araucarias), bennettites, cycads and, of course, ferns, horsetails and mosses.

Neogene

The Neogene period is the second period of the Cenozoic era. It began 25 million years ago and ended 1.8 million years ago. At this time, significant changes occurred in the composition of the fauna. A wide variety of gastropods and bivalves, corals, foraminifera and coccolithophores emerge. Amphibians have developed widely, sea ​​turtles and bony fish. During the Neogene period, terrestrial vertebrate forms also reached great diversity. For example, rapidly progressing hipparion species appeared: hipparions, horses, rhinoceroses, antelopes, camels, proboscideans, deer, hippopotamuses, giraffes, rodents, saber-toothed tigers, hyenas, apes and others.

Under influence various factors At this time, the organic world is rapidly evolving: forest-steppes, taiga, mountain and lowland steppes appear. In tropical areas - savannas and rain forests. Climatic conditions are approaching modern ones.

Geology as a science

The geological periods of the Earth are studied by the science of geology. It appeared relatively recently - at the beginning of the 20th century. However, despite her youth, she was able to shed light on many controversial issues about the formation of our planet, as well as the origin of the creatures inhabiting it. There are few hypotheses in this science; mostly only observational results and facts are used. There is no doubt that the traces of the planet’s development stored in the earth’s layers will in any case provide a more accurate picture of the past than any written book. However, not everyone can read these facts and understand them correctly, so even in this exact science, erroneous interpretations of certain events may arise from time to time. Where traces of fire are present, it can be confidently stated that there was fire; and where there are traces of water, we can say with equal confidence that there was water, and so on. And yet, mistakes also happen. In order not to be unfounded, let's consider one such example.

"Frosty patterns on glass"

In 1973, the magazine “Knowledge is Power” published an article by the famous biologist A. A. Lyubimtsev, “Frosty patterns on glass.” In it, the author draws the readers' attention to the striking similarities ice patterns with plant structures. As an experiment, he photographed the pattern on the glass and showed the photograph to a botanist he knew. And without hesitation he recognized the fossilized footprint of a thistle in the picture. From a chemical perspective, these patterns arise due to gas-phase crystallization of water vapor. However, something similar happens when producing pyrolytic graphite by pyrolysis of methane diluted with hydrogen. Thus, it was found that dendritic forms are formed away from this flow, which are very similar to plant remains. This is explained by the fact that there are general laws that govern the formation of forms in inorganic matter and living nature.

For a long time, geologists dated each geological period based on traces of plant and animal forms found in coal deposits. And only a few years ago, statements by some scientists appeared that this method was incorrect and that all the fossils found were nothing more than a by-product of the formation earth layers. There is no doubt that everything cannot be measured equally, but it is necessary to approach dating issues more carefully.

Was there a worldwide glaciation?

Let's consider another categorical statement by scientists, and not only geologists. All of us, starting from school, were taught about the worldwide glaciation that covered our planet, as a result of which many species of animals became extinct: mammoths, woolly rhinoceroses and many others. And the modern younger generation is being brought up on the Ice Age quadrology. Scientists unanimously assert that geology is an exact science that does not allow theories, but uses only verified facts. However, this is not the case. Here, as in many areas of science (history, archeology and others), one can observe the ossification of theories and the unshakability of authorities. For example, since the end of the nineteenth century, there have been heated debates on the sidelines of science about whether there was glaciation or not. In the mid-twentieth century, the famous geologist I. G. Pidoplichko published a four-volume work “On ice age" In this work, the author gradually proves the inconsistency of the version of global glaciation. He does not rely on the works of other scientists, but on the geological excavations he personally carried out (and some of them he carried out as a soldier of the Red Army, participating in battles against the German invaders) throughout the territory Soviet Union And Western Europe. He proves that the glacier could not cover the entire continent, but was only local in nature, and that it was not it that caused the extinction of many species of animals, but completely different factors - these are catastrophic events that led to the displacement of the poles (“Sensational History of the Earth”, A . Sklyarov); And economic activity the person himself.

Mysticism, or Why Scientists Don't Notice the Obvious

Despite the irrefutable evidence provided by Pidoplichko, scientists are in no hurry to abandon accepted version glaciation. And then it gets even more interesting. The author's works were published in the early 50s, but with the death of Stalin, all copies of the four-volume work were confiscated from the country's libraries and universities, preserved only in the library storage rooms, and obtaining them from there is very difficult. IN Soviet time everyone who wanted to borrow this book from the library was registered by the secret services. And even today there are certain problems in obtaining this printed publication. However, thanks to the Internet, anyone can familiarize themselves with the works of the author, who analyzes in detail the periods of the geological history of the planet and explains the origin of certain traces.

Is geology an exact science?

It is believed that geology is an exclusively experimental science that draws conclusions only from what it sees. If the case is doubtful, then she does not assert anything, expresses an opinion that allows for discussion, and postpones the final decision until unambiguous observations are received. However, as practice shows, exact sciences also make mistakes (for example, physics or mathematics). Nevertheless, mistakes are not a disaster if they are accepted and corrected in a timely manner. Often they don't wear global character, but have local significance, you just need to have the courage to accept the obvious, draw the right conclusions and move on, towards new discoveries. Modern scientists show radically opposite behavior, because most of the luminaries of science at one time received titles, awards and recognition for their activities, and today they do not want to part with them. And this behavior has been noticed not only in geology, but also in other fields of activity. Only strong people are not afraid to admit their mistakes; they rejoice at the opportunity to develop further, because discovering a mistake is not a disaster, but, on the contrary, a new opportunity.