Jurassic period climatic conditions. Jurassic period
, 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 a transitional form from reptiles to birds (in fact, it 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 ones, although 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.
Write a review about the article "Jurassic"
Notes
Literature
- Iordansky N. N. Development of life on earth. - M.: Education, 1981.
- Karakash N. I. ,.// 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
Yes, happy Napoleon,Having learned through experience what Bagration is like,
Alkidov doesn’t dare bother the Russians any more...”
But he had not yet finished the verses when the loud butler announced: “The food is ready!” The door opened, a Polish voice thundered from the dining room: “Roll out the thunder of victory, rejoice, brave Ross,” and Count Ilya Andreich, looking angrily at the author, who continued to read poetry, bowed to Bagration. Everyone stood up, feeling that dinner was more important than poetry, and again Bagration went to the table ahead of everyone. In the first place, between the two Alexanders - Bekleshov and Naryshkin, which also had significance in relation to the name of the sovereign, Bagration was seated: 300 people were seated in the dining room according to rank and importance, who was more important, closer to the guest being honored: as naturally as water spills deeper there, where the terrain is lower.
Just before dinner, Count Ilya Andreich introduced his son to the prince. Bagration, recognizing him, said several awkward, awkward words, like all the words he spoke that day. Count Ilya Andreich joyfully and proudly looked around at everyone while Bagration spoke with his son.
Nikolai Rostov, Denisov and his new acquaintance Dolokhov sat down together almost in the middle of the table. Opposite them, Pierre sat down next to Prince Nesvitsky. Count Ilya Andreich sat opposite Bagration with other elders and treated the prince, personifying Moscow hospitality.
His labors were not in vain. His dinners, fast and fast, were magnificent, but he still could not be completely calm until the end of dinner. He winked at the barman, whispered orders to the footmen, and, not without excitement, awaited each dish he knew. Everything was amazing. On the second course, along with the gigantic sterlet (when Ilya Andreich saw it, he blushed with joy and shyness), the footmen began popping the corks and pouring champagne. After the fish, which made some impression, Count Ilya Andreich exchanged glances with the other elders. - “There will be a lot of toasts, it’s time to start!” – he whispered and took the glass in his hands and stood up. Everyone fell silent and waited for him to speak.
- Health of the Emperor! - he shouted, and at that very moment his kind eyes were moistened with tears of joy and delight. At that very moment they started playing: “Roll the thunder of victory.” Everyone stood up from their seats and shouted hurray! and Bagration shouted hurray! in the same voice with which he shouted on the Shengraben field. The enthusiastic voice of young Rostov was heard from behind all 300 voices. He almost cried. “The health of the Emperor,” he shouted, “hurray!” – Having drunk his glass in one gulp, he threw it on the floor. Many followed his example. And the loud screams continued for a long time. When the voices fell silent, the footmen picked up the broken dishes, and everyone began to sit down, smiling at their shouts and talking to each other. Count Ilya Andreich stood up again, looked at the note lying next to his plate and proposed a toast to the health of the hero of our last campaign, Prince Pyotr Ivanovich Bagration and again Blue eyes The count was moistened with tears. Hooray! the voices of 300 guests shouted again, and instead of music, singers were heard singing a cantata composed by Pavel Ivanovich Kutuzov.
“All obstacles for the Russians are in vain,
Bravery is the key to victory,
We have Bagrations,
All enemies will be at your feet,” etc.
The singers had just finished when more and more toasts followed, during which Count Ilya Andreich became more and more emotional, and even more dishes were broken, and even more shouting. They drank to the health of Bekleshov, Naryshkin, Uvarov, Dolgorukov, Apraksin, Valuev, to the health of the foremen, to the health of the manager, to the health of all club members, to the health of all club guests, and finally, separately to the health of the founder of the dinner, Count Ilya Andreich. At this toast, the count took out a handkerchief and, covering his face with it, completely burst into tears.
Pierre sat opposite Dolokhov and Nikolai Rostov. He ate a lot and greedily and drank a lot, as always. But those who knew him briefly saw that some big change had taken place in him that day. He was silent the entire time of dinner and, squinting and wincing, looked around him or, stopping his eyes, with an air of complete absent-mindedness, rubbed the bridge of his nose with his finger. His face was sad and gloomy. He seemed to not see or hear anything happening around him, and was thinking about something alone, heavy and unresolved.
This unresolved question that tormented him, there were hints from the princess in Moscow about Dolokhov’s closeness to his wife and this morning the anonymous letter he received, in which it was said with that vile playfulness that is characteristic of all anonymous letters that he sees poorly through his glasses, and that his wife’s connection with Dolokhov is a secret only to him. Pierre decidedly did not believe either the princess’s hints or the letter, but he was now afraid to look at Dolokhov, who was sitting in front of him. Every time his gaze accidentally met Dolokhov’s beautiful, insolent eyes, Pierre felt something terrible, ugly rising in his soul, and he quickly turned away. Unwittingly remembering everything that had happened with his wife and her relationship with Dolokhov, Pierre saw clearly that what was said in the letter could be true, could at least seem true if it did not concern his wife. Pierre involuntarily recalled how Dolokhov, to whom everything was returned after the campaign, returned to St. Petersburg and came to him. Taking advantage of his carousing friendship with Pierre, Dolokhov came directly to his house, and Pierre accommodated him and lent him money. Pierre recalled how Helen, smiling, expressed her displeasure that Dolokhov lived in their house, and how Dolokhov cynically praised the beauty of his wife, and how from that time until his arrival in Moscow he was not separated from them for a minute.
“Yes, he is very handsome,” thought Pierre, I know him. It would be a special delight for him to dishonor my name and laugh at me, precisely because I worked for him and looked after him, helped him. I know, I understand what salt this should give to his deception in his eyes, if it were true. Yes, if it were true; but I don’t believe, I don’t have the right and I can’t believe.” He recalled the expression that Dolokhov's face took on when moments of cruelty came over him, like those in which he tied up a policeman with a bear and set him afloat, or when he challenged a man to a duel without any reason, or killed a coachman's horse with a pistol. . This expression was often on Dolokhov's face when he looked at him. “Yes, he’s a brute,” thought Pierre, it doesn’t mean anything to him to kill a man, it must seem to him that everyone is afraid of him, he must be pleased with this. He must think that I am afraid of him too. And really I’m afraid of him,” thought Pierre, and again with these thoughts he felt something terrible and ugly rising in his soul. Dolokhov, Denisov and Rostov were now sitting opposite Pierre and seemed very cheerful. Rostov chatted merrily with his two friends, one of whom was a dashing hussar, the other a famous raider and rake, and occasionally glanced mockingly at Pierre, who at this dinner impressed with his concentrated, absent-minded, massive figure. Rostov looked at Pierre unkindly, firstly, because Pierre, in his hussar eyes, was a rich civilian, the husband of a beauty, generally a woman; secondly, because Pierre, in the concentration and distraction of his mood, did not recognize Rostov and did not respond to his bow. When they began to drink the sovereign's health, Pierre, lost in thought, did not get up and take the glass.
, conglomerates formed in a variety of conditions.
Jurassic System Division
The Jurassic system is divided into 3 divisions 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 a transitional form from reptiles to birds (in fact, it 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.
Write a review about the article "Jurassic"
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 what can be found here good people. 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 the 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 circular “journey”... And, depending on his actions, returning to the “floors” can be very pleasant, or very scary...
Page 3 of 4
Jurassic period- this is the second (middle) period Mesozoic era. It begins 201 million years before our times, lasts 56 million years and ends 145 million years ago (according to other sources, the duration of the Jurassic period is 69 million years: 213 - 144 million years). Named after the mountains Yura, in which its sedimentary layers were first identified. Notable for the widespread proliferation of dinosaurs.
Main subsections of the Jurassic period, its geography and climate
In accordance with the classification adopted by the International Union of Geological Sciences, The Jurassic period is divided into three divisions- Lower - Leyas (stages - Hettangian, Sinemurian, Pliensbachian, Toarcian), Middle - Dogger (stages - Aalenian, Bayocian, Bathian, Callovian) and Upper Small (stages - Oxfordian, Kimmeridge, Tithonian).
| Jurassic period | Departments | tiers |
| Leyas (Lower) | Hettangian | |
| Sinemyursky | ||
| Pliensbachian | ||
| Toarsky | ||
| Dogger (Medium) | Aalensky | |
| Bayocian | ||
| Bathian | ||
| Callovian | ||
| Small (Upper) | Oxford | |
| Kimmeridge | ||
| Titonian |
During this period, the division of Pangea into component blocks - continents - continued. Upper Laurentia, which later became North America and Europe, finally separated from Gondwana, which again began to move south. As a result of this, the connection between global continents was disrupted, which had an important impact on the further evolution and development of flora and fauna. The differences that arose at that time are sharply expressed to this day.
The Tethys Sea, which expanded even more as a result of the divergence of the continents, now occupied most modern Europe. It originated from the Iberian Peninsula and, crossing the south and southeast of Asia diagonally, came out in Pacific Ocean. Most of what is now France, Spain and England were under his warm waters. On the left, as a result of the separation of the North American section of Gondwanaland, a depression began to emerge, which in the future became the Atlantic Ocean.
With the beginning of the Jurassic era average temperature on globe gradually began to decline, and therefore in the lower section Jurassic climate was close to temperate - subtropical. But closer to the middle, the temperature began to rise again, and by the beginning of the Cretaceous period the climate became a greenhouse.
Sea levels rose and fell slightly throughout the Jurassic, but average height sea level was an order of magnitude higher than in the Triassic. As a result of the divergence of continental blocks, a great many small lakes were formed, in which both plant and plant life began to develop and progress very quickly. animal life, so that the quantitative and qualitative level of flora and fauna of the Jurassic period soon caught up and surpassed the Permian level to the point of worldwide mass extinction.
Sedimentation
With a drop in temperature throughout the earth, multiple precipitation began to fall abundantly, which contributed to the advancement of vegetation, and then the animal world, into the depths of the continents, which is due to Jurassic sedimentation. But the formation products are the most intense for this period earth's crust under the influence of continental shifts, and as a consequence - volcanic and other seismic activity. These are various igneous, clastic rocks. There are large deposits of shale, sand, clay, conglomerates, and limestone.
The warm and stable climate of the Jurassic period greatly contributed to the rapid development, formation and evolutionary improvement of both previous and new life forms. (Fig. 1) rose to a new level in comparison with the sluggish Triassic, which did not particularly shine with varieties.
Rice. 1 - Animals of the Jurassic period
The Jurassic seas were full of various marine invertebrates. Belemnites, ammonites, and all kinds of sea lilies. And although there were an order of magnitude fewer ammonites in the Jurassic than in the Triassic, they for the most part had a more developed body structure than their ancestors from the previous era, with the exception of phyloceras, which did not change at all during the millions of years of transition from the Triassic to the Jurassic. It was at that time that many ammonites acquired their indescribable mother-of-pearl coating, which has survived to this day. Ammonites were found in large quantities, both in the distant oceanic depths and in the warm coastal and inland seas.
Belemnites reached unprecedented development in the Jurassic era. They gathered in flocks and roamed the depths of the sea in search of unwary prey. Some of them at that time reached three meters in length. The remains of their shells, nicknamed “devil’s fingers” by scientists, are found almost everywhere in Jurassic sediments.
There were also numerous bivalve mollusks belonging to the oyster species. At that time, they began to form peculiar oyster banks. Numerous sea urchins, which abundantly populated reef areas at that time. Some of them have successfully survived to this day. But many, such as elongated hedgehogs of irregular shapes that had a jaw apparatus, became extinct.
Insects also took a big step in their development. Their visual, flying and other devices were increasingly improved. More and more varieties appeared among barnacles, decapods, and leaf-footed crustaceans; most freshwater sponges and caddisflies multiplied and evolved. Ground Jurassic insects were replenished with new varieties of dragonflies, beetles, cicadas, bugs, etc. Along with the emergence of a huge number of flowering plants, a large number of pollinating insects that feed on flower nectar.
But it was reptiles that achieved the greatest development in the Jurassic era - dinosaurs. By the middle of the Jurassic period, they completely took over all land areas, displacing or destroying their reptilian predecessors, from whom they descended, in the pursuit of food.
IN sea depths already at the beginning of the Jurassic period reigned supreme dolphin-like ichthyosaurs. Their long heads had strong, elongated jaws studded with rows of sharp teeth, and large, highly developed eyes were framed by bone-plate rings. By the middle of the period they had become real giants. The length of the skull of some ichthyosaurs reached 3 meters, and the body length exceeded 12 meters. The limbs of these aquatic reptiles evolved under the influence of underwater life and consisted of simple bony plates. Elbows, metatarsals, hands and fingers ceased to differ from each other; one huge flipper supported more than a hundred bone plates of various sizes. The shoulder and pelvic girdles became underdeveloped, but this was not necessary, since mobility in aquatic environment they were provided with additionally grown powerful fins.
Another reptile that seriously and permanently settled in the depths of the sea was plesiosaur. They, like ichthyosaurs, arose in the seas during the Triassic period, but in the Jurassic period they branched into two varieties. Some had long neck and a small head (plesiosaurs), in others the head became an order of magnitude larger, and the neck was much shorter, which is why they became more like underdeveloped crocodiles. Both of them, unlike ichthyosaurs, still needed rest on land, and therefore often crawled onto it, becoming the prey of land giants, such as, for example, a tyrannosaurus or herds of smaller predatory reptiles. Very agile in the water, on land they were clumsy fur seals our time. Pliosaurs were much more maneuverable in the water, but what plesiosaurs lacked in agility they made up for with their long necks, which allowed them to instantly grab prey no matter what position their bodies were in.
All kinds of fish species multiplied unusually in the Jurassic period. The water depths were literally teeming with a motley variety of coral ray-finned, cartilaginous and ganoids. Sharks and rays were also diverse, still constituting, due to their extraordinary agility, speed and agility developed over hundreds of millions of years of evolution, Jurassic underwater reptile predators. Also during this period, many new varieties of turtles and toads appeared.
But the terrestrial diversity of reptile dinosaurs was truly remarkable. (Fig. 2) were from 10 centimeters to 30 meters in height. Many of them were simple, harmless herbivores, but often there were also ferocious predators.
Rice. 2 - Jurassic Dinosaurs
One of the largest herbivorous dinosaurs was brontosaurus(now - Apatosaurus). Its body weighed 30 tons, its length from head to tail reached 20 meters. And despite the fact that his height at the shoulders reached only 4.5 meters, with the help of his neck, which reached a length of 5-6 meters, they perfectly ate up tree foliage.
But most huge dinosaur of that era, as well as the absolute champion among all animals of the Earth of all times, was a 50-ton herbivore brachiosaurus. With a body length of 26 m, he had such a long neck that when it stretched upward, his small head was 13 meters above the ground. To feed itself, this huge reptile needed to consume up to 500 kg of green mass every day. It is noteworthy that with such truly gigantic body sizes, his brain weighed no more than 450 grams.
It is appropriate to say a few words about predators, of which there were also many in the Jurassic period. The most gigantic and dangerous predator Jurassic is considered 12 meters tyrannosaurus, but as scientists have proven, this predator was more opportunistic in its views on food. He rarely hunted, often preferring carrion. But they were truly dangerous allosaurus. With a height of 4 meters and a length of 11 meters, these reptile predators hunted prey that was many times larger than them in weight and other parameters. Often they, huddled in a herd, attacked such herbivorous giants of that era as the Camarasaurus (47 tons) and the aforementioned Apatosaurus.
We came across more small predators, for example, such as the 3-meter dilophosaurus, which weighed only 400 kg, but flocked together and attacked even larger predators.
In view of the ever-increasing danger from predatory individuals, evolution has awarded some herbivorous individuals with formidable elements of defense. For example, such a herbivorous dinosaur as centrosaurus was endowed with elements of protection in the form of huge sharp spikes on the tail and sharp plates along the ridge. The spikes were so large that with a strong blow, the Kentrosaurus would have pierced through a predator such as a Velociraptor or even a Dilophosaurus.
For all that animal world Jurassic period was carefully balanced. The population of herbivorous lizards was regulated by predatory lizards, predators were restrained by many smaller predators and aggressive herbivores, like stegosaurs. Thus, the natural balance was maintained for many millions of years, and what contributed to the extinction of dinosaurs in Cretaceous period it is still not known.
By the middle of the Jurassic period air space was filled with many flying dinosaurs such as pterodactyls and other pterosaurs. They glide quite skillfully in the air, but in order to take to the skies, they needed to climb to impressive heights. These, for the most part, were not very mobile specimens of ancient mammals, but from the air they could very successfully track and attack prey in a pack method. Smaller representatives of flying dinosaurs preferred to make do with carrion.
In Jurassic sediments, the remains of a fledgling archaeopteryx lizard, which has long been considered by scientists to be the ancestor of birds, were found. But, as was recently scientifically proven, this species of lizard was a dead end. Birds evolved mainly from other species of reptiles. Archeopteryx had a long feathered tail, jaws studded with small teeth, and the feathered wings had developed fingers, with the help of which the animal grabbed branches. Archeopteryx flew poorly, mainly gliding from branch to branch. Basically, they preferred to climb tree trunks, digging into their bark and branches with the help of sharp curved claws. It is noteworthy that in our time only the chicks of the hoatzin bird have fingers on their wings.
The first birds, represented by small dinosaurs, jumped high either in an attempt to reach insects fluttering in the sky, or in order to escape from predators. In the process of evolution, they became more and more feathered, their jumps became longer and longer. During the jumping process, the future birds helped themselves more and more intensively by waving their forelimbs. Over time, their now wings, and not just forelimbs, acquired more and more powerful muscles, and the structure of their bones became hollow, as a result of which total weight birds became much easier. And all this led to the fact that by the end of the Jurassic period, the air space of the Jurassic, along with pterosaurs, was plowed by a large number of all kinds of ancient birds.
In the Jurassic period they actively reproduced and small mammals. But still they were not allowed to express themselves widely, since the ubiquitous power of dinosaurs was too overwhelming.
Since, during the process of climate change, the vast deserts of the Triassic began to be abundantly irrigated by precipitation, this created the preconditions for the advancement of vegetation further into the continents, and closer to the middle of the Jurassic period, almost the entire surface of the continents was covered with lush vegetation.
All low-lying places are abundantly overgrown with ferns, cycads and coniferous thickets. The sea coasts were occupied by araucarias, thujas and, again, cycads. Also, vast land masses were occupied by ferns and horsetails. Despite the fact that by the beginning of the Jurassic period the vegetation on the continents of the northern hemisphere was relatively uniform, by the middle of the Jurassic two already established and strengthened main belts of vegetation massifs were formed - northern and southern.
Northern belt was notable for the fact that at that time it was formed mainly by ginkgo plants mixed with herbaceous ferns. With all that half all vegetation northern latitudes Jurassic period consisted of varieties of ginkgo, today only one species of these plants has miraculously survived.
Southern belt were mainly cycads and tree ferns. At all Jurassic plants(Fig. 3) more than half still consisted of various ferns. Horsetails and mosses of those times were almost no different from today. In those places where cordaite and ferns grew en masse during the Jurassic period, this moment tropical cycad jungle grows. Of the gymnosperms, cycads were the most common in the Jurassic. Nowadays they can only be found in tropical and subtropical zones. It was these, with their crowns reminiscent of modern palm trees, that most herbivorous dinosaurs fed on.
Rice. 3 - Plants of the Jurassic period
In the Jurassic period northern latitudes Deciduous ginkgos began to appear for the first time. And in the second half of the period, the first spruce and cypress trees appeared. Coniferous forests The Jurassic looked very much like modern ones.
Minerals of the Jurassic period
The most pronounced mineral resources dating back to the Jurassic period are European and North American chromite deposits, Caucasian and Japanese copper-pyrite deposits, Alpine deposits of manganese ores, tungsten ores of the Verkhoyansk-Chukotka region, Transbaikalia, Indonesia, and the North American Cordillera. Also to this era can be attributed deposits of tin, molybdenum, gold and other rare metals scattered throughout, formed in the late Cimmerian era and thrown to the surface as a result of granitoid mechanisms associated with the separation of continents that took place at the end of the Jurassic period. Iron ore deposits are numerous and widespread. There are uranium ore deposits on the Colorado Plateau.
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 was highly variable.
From the Aalenian to the Bathonian ages, the climate was warm and humid. Then there was glaciation, which occupied most of the Callovian, Oxfordian and the beginning of the Kimmeridgian, and then the climate warmed again.
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 characteristics of birds and reptiles is Archeopteryx. 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 On the Origin of Species and became a strong argument in favor of the theory of evolution - it was initially considered a transitional form from reptiles to birds. But later it was also proposed that 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
Jurassic geological period, Jura, Jurassic system, middle period Mesozoic. Began 200-199 million years ago. n. and ended 144 million liters. n.
For the first time, deposits of this period were discovered and described in the Jura (mountains in Switzerland and France), hence the name of the period. The deposits of the Jurassic period are very diverse: limestones, clastic rocks, shales, igneous rocks, clays, sands, conglomerates, formed in a variety of conditions. The deposits of that time are quite diverse: limestones, clastic rocks, shales, igneous rocks, clays, sands, conglomerates, formed in a wide variety of conditions.
Jurassic tectonics: At the beginning of the Jurassic period, the single supercontinent Pangea began to break up into separate continental blocks. Shallow seas formed between them. 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. It was due to this that the climate of the Jurassic period became more humid. During the Jurassic period, the outlines of the continents began to form: Africa, Australia, Antarctica, Northern and South America. And although they are located differently than now, they were formed precisely in the Jurassic period.
Climate and vegetation of the Jurassic period
Volcanic activity at the end of the Triassic - beginning of the Jurassic period caused transgression of the sea. The continents separated and the climate in the Jurassic period became more humid than in the Triassic. In place of deserts Triassic period, lush vegetation grew during the Jurassic period. Huge areas were covered with lush vegetation. Jurassic forests consisted primarily of ferns and gymnosperms.
Warm and humid climate the Jurassic period contributed to the rapid development flora planets.
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. n. Throughout the northern hemisphere, the vegetation was quite monotonous. In the northern plant belt ginkgo and herbaceous ferns predominated. 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 of the Jurassic period are still preserved in some corners today. wildlife. Horsetails and mosses were almost no different from modern ones.
animals: Jurassic period - the dawn of the age of dinosaurs. It was the lush development of vegetation that contributed to the emergence of many species of herbivorous dinosaurs. The increase in the number of herbivorous dinosaurs gave impetus to the increase in the number of predators. Dinosaurs settled all over the land and lived in forests, lakes, and swamps. The range of differences between them is so great that family ties between them are established with great difficulty. The diversity of dinosaur species during the Jurassic period was great. They could be the size of a cat or chicken, or they could reach the size of huge whales.
The Jurassic period is the time of habitation of many famous dinosaurs. Of the lizards, these are Allosaurus and Diplodocus. Of the ornithischians, this is the stegosaurus.
During the Jurassic period, winged lizards - pterosaurs - reigned supreme in the air. They appeared in the Triassic, but their heyday was precisely in the Jurassic period. Pterosaurs were represented by two groups: pterodactyls and rhamphorhynchus.
During the Jurassic period, the first birds or something between birds and lizards appeared. Creatures that appeared in the Jurassic period and have the properties of lizards and modern birds are called Archeopteryx. The first birds were Archeopteryx, the size of a pigeon. Archeopteryx lived in forests. They ate mainly insects and seeds.
Bivalves displace brachiopods from shallow waters. Brachiopod shells are replaced by oysters. Bivalve mollusks fill all life niches of the seabed. Many stop collecting food from the ground and switch to pumping water using their gills. In warm and shallow seas Other important events took place during the Jurassic period.
The Jurassic period gave rise to many species of plesiosaurs and ichthyosaurs, rivaling the fast-moving sharks and extremely agile bony fish. and in the depths of the sea, Leopleuradon non-stop patrolled its territory in search of food.
But one creature could rightfully be called the master of the Jurassic seas. This is a giant Liopleurodon weighing up to 25 tons. Liopleurodon was the most dangerous predator of the Jurassic seas, and perhaps in the entire history of the planet.
