Jurassic period, description of the Jurassic period, dinosaurs of the Jurassic period, dinosaurs of the Jurassic period. Jurassic period, description of the Jurassic period, dinosaurs of the Jurassic period, lizards of the Jurassic period What historical period follows the Jurassic

, conglomerates formed in a variety of conditions.

Jurassic subdivision

The Jurassic system is subdivided into 3 divisions and 11 tiers:

system	the Department	tier	Age, million years ago
Chalk	Lower	Berriasian	smaller
Yura	Upper (malm)	titonian	152,1-145,0
		Kimmeridge	157,3-152,1
		Oxford	163,5-157,3
	Medium (dogger)	Callovian	166,1-163,5
		Bath	168,3-166,1
		Bayosian	170,3-168,3
		Aalen	174,1-170,3
	Lower (lias)	Toarian	182,7-174,1
		Plinsbachsky	190,8-182,7
		Sinemursky	199,3-190,8
		Goettansky	201,3-199,3
Triassic	Upper	Rhetic	more
The division is given in accordance with 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).

Vegetation

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

land animals

One of the fossil creatures that combine the features of birds and reptiles is Archeopteryx, or the first bird. For the first time, his skeleton was discovered in the so-called lithographic slates in Germany. The find was made two years after the publication of Charles Darwin's work " 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 that was not directly related to real birds) . Archeopteryx flew rather poorly (planned from tree to tree), and was about 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, they were preserved only in hoatzin chicks).

In the Jurassic period, small, woolly warm-blooded animals live on Earth - mammals. They live next to dinosaurs and are almost invisible against their background. In the Jurassic, the division of mammals into monotremes, marsupials, and placentals took place.

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Notes

Literature

• Jordan N. N. development of life on earth. - M .: Enlightenment, 1981.
• Karakash N.I.,. Jurassic system and period // Brockhaus and Efron Encyclopedic Dictionary: 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 .: Thought, 1984.
• Yasamanov N.A. Ancient climates of the Earth. - L.: Gidrometeoizdat, 1985.
• Yasamanov N.A. Popular paleogeography. - M .: Thought, 1985.

Links

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

←	P a l e about h about th	Mesozoic (252.2-66.0 Ma)			To a th n about h about 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 naked and featureless, lazily moving their drooping, thorny branches. Farther behind them stretched a bleak, burnt-out steppe, lost in the distance behind a wall of dirty, gray fog... True, it did not cause the slightest pleasure to make one want to look at it ... The whole landscape evoked horror and longing, seasoned with hopelessness ...
- Oh, how scary it is here ... - Stella whispered, shivering. – 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. After all, no one sent them here - they just got what they deserved, right? Still not giving up, I said.
“Now look…” Stella whispered mysteriously.
Before us suddenly appeared a cave overgrown with grayish greenery. And out of it, squinting, stepped out a tall, stately man who in no way fit into this miserable, chilling landscape ...
- Hello, Sad! Stella greeted the stranger affectionately. - I brought a friend! She does not 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, - Yes, I'm not so good to show me to someone. You are right...
Oddly enough, but this sad man I really liked something right away. He exuded strength and warmth, and it was very pleasant to be near him. In any case, he did not in any way resemble those weak-willed, heartbroken people who surrendered to the mercy of fate with whom this “floor” was packed.
“Tell us your story, sad person…” Stella asked with a light smile.
“Yes, there is nothing to tell there, and there is nothing special to be proud of ...” the stranger shook his head. - And what do you need it for?
For some reason, I felt very sorry for him... Even without knowing anything about him, I was already almost sure that this person could not have done something really bad. Well, I just couldn’t!.. Stella, smiling, followed my thoughts, which she apparently liked very much ...
- Well, okay, I agree - you're right! .. - Seeing her satisfied face, I finally honestly admitted.
“But you don’t know anything about him yet, and everything is not so simple with him,” Stella said with a sly smile. “Well, please tell her, Sad…”
The man smiled sadly at us, and quietly said:
- I'm here because I killed ... I killed many. But not by desire, but by need, it was ...
I was immediately terribly upset - I killed! .. And I, stupid, believed! .. But for some reason I stubbornly did not have the slightest feeling of rejection or hostility. I obviously liked the person, and no matter how hard I tried, I couldn’t do anything about it ...
“Is it the same fault to kill at will or out of necessity?” I asked. Sometimes people don't have a choice, do they? For example: when they have to defend themselves or protect others. I have always admired heroes – warriors, knights. In general, I have 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’m here says that the guilt is the same... But from the way I feel this guilt in my heart, then no... I never wanted to kill, I just I defended my land, I was a hero there... But here it turned out that I was just killing... Is that right? I think no...
So you were a warrior? I asked hopefully. - But then, it's a big difference - you defended your home, your family, your children! And you don't look like a killer!
– Well, we are all different from what others see us... Because they only see what they want to see... or only what we want to show them... As for the war, I also first just as you thought, 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 happened.
– But this is not right! .. – I was indignant. - What then happens - a maniac-killer turns out to be the same as a hero?! .. This simply cannot be, this should not be!
Everything in 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 life in the same way. Only, probably, there are “extenuating circumstances”, since a person who protects someone, even if he takes his life, is 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, you believe me ...
- And can I ask you - how long have you lived? I asked, a little embarrassed.
– Oh, quite a long time ago... This is the second time I've been here... For some reason, my two lives were similar - in both I fought for someone... Well, and then I paid... And it's always just as bitter ... - the stranger was silent for a long time, as if not wanting to talk about it anymore, but then he continued quietly. There are people who love to fight. I've always hated it. But for some reason, life brings me back 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 captured foreign lands - others the lands were protected. Sons overthrew their fathers, brothers killed their brothers... Everything happened. Someone accomplished unthinkable feats, someone betrayed someone, and someone turned out to be just a coward. But none of them even suspected how bitter the payment for everything they did in that life would be ...
- Did you have a 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 died... And some are already living again. That was a long time ago...
– And you are still here?!.. – I whispered, looking around in horror.
I could not even imagine that he had existed here like this for many, many years, suffering and "paying" his guilt, without any hope of leaving this terrifying "floor" even before his hour of return to the physical came. 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 right here!) With a whole new “baggage”, good or bad, depending on how he will live his “next” earthly life... And he could not have any hope to free himself from this vicious circle (whether it be good or bad), since, having begun his earthly life, each person “dooms” himself to this endless, an eternal circular "journey"... And, depending on his actions, returning to the "floors" can be very pleasant, or very scary...

Our planet is several billion years old, and man appeared on it not so long ago. And millions of years ago, completely different creatures dominated the Earth - powerful, fast and huge. Of course, we are talking about dinosaurs that inhabited almost the entire surface of the planet many centuries ago. The number of species of these animals is quite large, and it can be said with certainty that the dinosaurs and the Jurassic world as a whole were the most diverse. And this era can be considered the heyday of the life of all flora and fauna.

Life is everywhere

The Jurassic period took place 200-150 million years ago. Quite a hot climate is characteristic of that time. Dense vegetation, lack of snow and cold led to the fact that life on earth was everywhere: on land, in air and in water. The increased humidity of the air led to the violent growth of plants, which became the food of herbivores, which grew to gigantic sizes. But they, like smaller animals, served as food for predators, the diversity of which is quite interesting.

The level of the World Ocean was much higher than now, and the favorable climate led to a rich variety of life in the water. The shallow waters teemed with mollusks and small animals, which became food for large marine predators. Life in the air was no less intense. The flying dinosaurs of the Jurassic period - pterosaurs - have seized dominance in the sky. But in the same period, the ancestors of modern birds appeared, in the wings of which there were no leather membranes, but feathers were born.

herbivorous dinosaurs

The Jurassic era gave the world many large reptiles. Most of them reached fantastically gigantic sizes. The largest dinosaur of the Jurassic period - diplodocus, which lived on the territory of the modern United States, reached a length of 30 meters and weighed almost 10 tons. It is noteworthy that the animal ate not only plant foods, but also stones. This was necessary so that small pebbles rubbed vegetation and tree bark in the animal's stomach. After all, the teeth of diplodocus were very small, no larger than a human fingernail, and could not help the animal to thoroughly chew plant foods.

An equally large brachiosaurus had a mass exceeding the weight of 10 elephants, and reached 30 meters in height. This animal lived on the territory of modern Africa and fed on the leaves of coniferous trees and cycads. Such a giant easily absorbed almost half a ton of plant food per day and preferred to settle near water bodies.

An interesting representative of herbivores of this era - Kentrosaurus - lived on the territory of modern Tanzania. This dinosaur of the Jurassic period was interesting for its body structure. On the back of the animal there were large plates, and the tail was covered with large spikes that helped to fight off predators. The animal was about 2 meters in height and up to 4.5 meters in length. The Kentrosaurus weighed a little over half a ton, making it the most agile dinosaur.

jurassic

The diversity of herbivores leads to the emergence of a large number of predators, because nature always keeps a balance. The largest and bloodthirsty dinosaur of the Jurassic period, the Allosaurus, reached a length of almost 11 meters and a height of 4 meters. This predator with a weight of 2 tons hunted in the United States and Portugal and earned the title of the fastest runner.

He ate not only small animals, but, uniting in groups, hunted even very large prey, such as apatosaurs or camarasaurus. To do this, a sick or young individual was beaten off from the herd by common efforts, after which they were collectively devoured.

A fairly well-known dilophosaurus, which lived on the territory of modern America, reached three meters in height and weighed up to 400 kilograms.

A fast predator with characteristic crests on its head, a rather bright representative of that period, similar to tyrannosaurs. He hunted small dinosaurs, but in a pair or a flock he could also attack an animal that was much larger than him. Great maneuverability and speed allowed Dilophosaurus to catch even a fairly fast and miniature Scutellosaurus.

Marine life

Land is not the only place that dinosaurs settled, and the world of the Jurassic period in the water was also diverse and multifaceted. A prominent representative of that era was the plesiosaur. This waterfowl predatory lizard had a long neck and reached a length of up to 18 meters. The structure of the skeleton with a short but rather wide tail and powerful paddle-like fins allowed this predator to develop great speed and reign in the depths of the sea.

An equally interesting marine dinosaur of the Jurassic period is an ichthyosaur, similar to a modern dolphin. Its peculiarity was that, unlike other lizards, this predator gave birth to live cubs, and did not lay eggs. The ichthyosaur reached 15 meters in length and hunted smaller prey.

sky kings

By the end of the Jurassic period, small pterodactyl predators conquered the heavenly heights. The wingspan of this animal reached one meter. The body of the predator was small and did not exceed half a meter, the weight of an adult individual reached 2 kilograms. The predator could not take off, and before flying, he had to climb a rock or ledge. The pterodactyl ate fish, which he could see at a considerable distance. But he himself sometimes became a victim of predators, because on land he was quite slow and clumsy.

Another representative of the flying dinosaurs was rhamphorhynchus. Slightly larger than a pterodactyl, this predator weighed three kilograms and had a wingspan of up to two meters. Habitat - Central Europe. A feature of this winged dinosaur was a long tail. Sharp teeth and powerful jaws made it possible to catch slippery and wet prey, and the basis of the animal's diet was fish, shellfish and, surprisingly, small pterodactyls.

living world

The world in that era is striking in its diversity: far from the only population of the Earth at that time were dinosaurs. And animals of the Jurassic period of other classes were quite common. After all, it was then, thanks to good conditions, that turtles appeared in the form that we are now familiar with. Frog-like amphibians bred, which became food for small dinosaurs.

The seas and oceans teemed with many kinds of fish, such as sharks, rays, and other cartilaginous and bony ones. they are also belemnites, they were the lowest link in the food chain, but their multi-membered population supported life in the water. During this period, crustaceans appear, such as barnacles, phyllopods, and freshwater sponges.

Intermediate

The Jurassic period is notable for the appearance of bird ancestors. Of course, Archeopteryx was not that much like a modern bird, it was more like a miniraptor with feathers.

But a later ancestor, also known as Longipteryx, already resembled a modern kingfisher. Although birds for that era are a rather rare occurrence, they are the ones that give rise to a new round in the evolution of the animal world. The dinosaurs of the Jurassic period (the photo is presented above) died out long ago, but even now, looking at the remains of such giants, you are in awe of these giants.

Jurassic geological period, Jura, Jurassic system, middle period of the Mesozoic. It began 206 million years ago and lasted 64 million years.

For the first time deposits of the Jurassic period were described in the Jura (mountains in Switzerland and France), hence the name of the period. The deposits of that time are quite diverse: limestones, clastic rocks, shales, igneous rocks, clays, sands, conglomerates, formed in a variety of conditions.

190-145 million years ago, during the Jurassic period, 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).

In the Jurassic period, vast areas were covered with lush vegetation, primarily a variety of forests. They mainly consisted of ferns and gymnosperms.

cycads- a class of gymnosperms that prevailed in the green cover of the Earth. Now they are found here and there in the tropics and subtropics. Dinosaurs roamed under the canopy of these trees. Outwardly, cycads are so similar to low (up to 10-18 m) palm trees that even Carl Linnaeus placed them among palm trees in his plant system.

In the Jurassic period, groves of ginkgo trees grew throughout the then temperate zone. Ginkgoes are deciduous (unusually for gymnosperms) trees with an oak-like crown and small, fan-shaped leaves. Only one species has survived to this day - ginkgo biloba. Very diverse were conifers, similar to modern pines and cypresses, which flourished at that time not only in the tropics, but had already mastered the temperate zone.

marine organisms

Compared with the Triassic, the population of the seabed has changed a lot. Bivalves displace brachiopods from shallow waters. Brachiopod shells are replaced by oysters. Bivalve molluscs fill all the vital niches of the seabed. Many stop collecting food from the ground and move on to pumping water with the help of gills. A new type of reef communities is emerging, approximately the same as it exists now. It is based on six-ray corals that appeared in the Triassic.

land animals

One of the fossil creatures of the Jurassic period, combining the features of birds and reptiles, is Archeopteryx, or the first bird. For the first time, his skeleton was discovered in the so-called lithographic slates 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. Archeopteryx still flew rather poorly (planned from tree to tree), and was about 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, they were preserved only in hoatzin chicks).

In the Jurassic period, small, woolly warm-blooded animals - mammals - live on Earth. They live next to dinosaurs and are almost invisible against their background.

Dinosaurs of the Jurassic period ("terrible lizards" from Greek) lived in ancient forests, lakes, swamps. The range of differences between them is so great that family ties between them are established with great difficulty. They could be the size of a cat or a chicken, or they could reach the size of huge whales. Some of them moved on four limbs, while others ran on their hind legs. Among them were clever hunters and bloodthirsty predators, but there were also harmless herbivorous animals. The most important feature common to all their species is that they were land animals.

From 213 to 144 million years ago.
By the beginning of the Jurassic period, the giant supercontinent Pangea was in the process of active decay. South of the equator, there was still a single vast mainland, which was again called Gondwana. Later, 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 freely 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. In the Jurassic landscape, horsetails and club mosses grew thickly, which survived from the Triassic period. Palm-shaped bennettites have also been preserved. In addition, there were many griots around. Extensive forests of seed, common and tree ferns, as well as fern-like cycads, spread from water bodies 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 split apart, new seas and straits arose, in which new types of animals and algae found refuge. Gradually, fresh sediments accumulated on the seabed. Many invertebrates settled in them, such as sponges and bryozoans (sea mats). Other important events took place in warm and shallow seas. Giant coral reefs formed there, sheltering numerous ammonites and new varieties of belemnites (old relatives of today's octopuses and squids).
On land, in lakes and rivers, many different species of crocodiles lived, widely settled around 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 it easier to swim. Tail fins allowed them to reach greater speed in water than on land. New species of sea turtles have also appeared. Evolution also gave rise to many species of plesiosaurs and ichthyosaurs that competed with new, fast-moving sharks and extremely mobile bony fish.

This cycad is a living fossil. It almost does not differ from its relatives that grew on Earth in the Jurassic period. Now 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 a calcareous substance, is called the rostrum. At the anterior end of the rostrum there was a cavity with a fragile multi-chambered shell, which helped the animal to 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 best preserved in fossil form than any other body part of a belemnite, and it is usually this that falls into the hands of scientists. But sometimes, non-roster fossils are also found. The first such finds at the beginning of the XIX century. baffled many experts. They guessed that they were dealing with the remains of belemnites, but without the accompanying rostrum, these remains looked rather strange. The answer to this mystery turned out to be extremely simple, as soon as more data was collected about the way the ichthyosaurs feed - the main enemies of the belemnites. The rostless fossils appear to have formed when an ichthyosaur, after swallowing a whole school of belemnites, regurgitated the soft parts of one of the animals while its hard internal skeleton remained in the predator's stomach.
Belemnites, like modern octopuses and squids, developed an inky liquid and used it to create a "smoke screen" when they tried to escape from predators. Scientists have also discovered fossilized belemnite ink sacs (organs in which a supply of ink liquid was stored). One of the scientists of the Victorian era, William Buckland, even managed to extract some of the ink from fossil ink bags, which he used to illustrate his book Bridgewater Treatise.

Plesiosaurs, barrel-shaped marine reptiles with four wide flippers that they rowed through the water like oars.
Glued fake.

No one has yet been able to find a whole fossil belemnite (soft part plus rostrum), although in the 70s. 20th century in Germany, a rather ingenious attempt was made to fool the whole scientific world with a clever forgery. Whole fossils, allegedly taken from a quarry in southern Germany, were purchased by several museums at a very high price, before it was discovered that in all cases the calcareous rostrum was carefully glued to the fossil 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 considered the Loch Ness monster to be a living plesiosaur.

Mary Anning (1799 - 1847) was only 2 years old when she discovered the first ichthyosaur fossil at Lyme Regis in Dorothy, England. Subsequently, she was lucky to find also the first fossil skeletons of a plesiosaur and a pterosaur.
This child could find
Glasses, pins, nails.
But got in the way
Ichthyosaurus 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 various sizes and long narrow jaws. The largest of them reached a length of about 8 m, but many species did not exceed a person in size. They were excellent swimmers, feeding mainly on fish, squid and nautiloids. Although ichthyosaurs belonged to reptiles, their fossil remains suggest that they were viviparous, that is, they produced ready-made offspring, like mammals. Perhaps the young ichthyosaurs were born in the open sea, like whales.
Another group of predatory reptiles, also widespread in the Jurassic seas, are the plesiosaurs. Their long-necked varieties lived near the surface of the sea. Here they hunted for shoals of very large fish with their flexible necks. Short-necked species, the so-called pliosaurs, preferred life at great depths. They ate ammonites and other molluscs. Some large pliosaurs appear to have preyed on smaller plesiosaurs and ichthyosaurs as well.

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

In the Jurassic period, the evolution of insects accelerated dramatically, and as a result, the Jurassic landscape eventually filled with endless buzzing and crackling, which were emitted by many new types of insects, crawling and flying everywhere. Among them were predecessors
modern ants, bees, earwigs, flies and wasps. Later, in the Cretaceous period, there was a new evolutionary explosion, when insects began to "make contacts" with the newly appeared flowering plants.
Until that 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 plan. Now whole hordes of pterosaurs have risen into the air. These were the first and largest flying vertebrates. Although the first pterosaurs appeared at the end of the Triassic, their true "rise" occurred precisely in the Jurassic period. Light 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. In some fossil pterosaurs, hair is guessed. 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 soared like vultures above the ground in the streams of rising hot air. Perhaps they even skimmed over the surface of the ocean, drawn by sea winds, like modern albatrosses. However, now some experts believe that pterosaurs could flap their wings, that is, actively fly, like birds. Perhaps some of them even walked like a bird, while others dragged their bodies along the ground or slept in the nesting places of relatives, hanging upside down, like bats.

Data obtained from the analysis of the fossilized stomachs and dung (coprolites) of ichthyosaurs suggest that their diet consisted mainly of fish and cephalopods (ammonites, nautiloids and squids). The contents of the stomachs of ichthyosaurs made it possible to make an even more curious discovery. The small, hard spines on the tentacles of squid and other cephalopods seem to have been a nuisance to the ichthyosaurs, as they were not digested and therefore could not pass freely through their digestive system. As a result, the spikes accumulated in the stomach, and from them scientists manage to find out what the animal ate throughout its life. So, when studying the stomach of one of the fossil ichthyosaurs, it turned out that he swallowed at least 1500 squids!
How birds learned to fly.

There are two main theories trying 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 began with the fact that bipedal animals, the predecessors of birds, ran and jumped 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 large, 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 the wings, and it will become clear to you how, after a long time, these "pioneers of aeronautics" learned to stay in flight for a long time, and their wings gradually acquired properties that allowed them to support the body 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 way to flying should have been planning, since with this type of movement, energy costs are extremely insignificant - in any case, much less than with the "running-jumping" theory. The animal does not need to make additional efforts, because when planning it is pulled down by the force of the earth's gravity.

The first fossil Archeopteryx was discovered two years after the publication of Charles Darwin's On the Origin of Species. This important discovery was another confirmation of Darwin's theory that evolution is very slow and that one group of animals gives birth to another, undergoing a series of successive transformations. The famous scientist and close friend of Darwin, Thomas Huxley, predicted the existence of an animal like Archeopteryx in the past, even before its remains fell into the hands of scientists. In fact, Huxley described this animal in detail before it was discovered!
Step flight.

One scientist proposed an extremely curious theory. It describes a series of stages through which the "pioneers of aeronautics" had to pass in the course of the evolutionary process that eventually turned them into flying animals. According to this theory, once one of the groups of small reptiles, called pro-topts, switched to an arboreal way of life. Perhaps the reptiles climbed trees because it was safer there, or easier to get food, or more convenient to hide, sleep, equip nests. It was cooler on 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 welcome - they provided additional thermal insulation and increased the surface area of ​​the winged "arms".
In turn, soft, feathered forelimbs softened the impact on the ground when the animal lost balance and fell from a 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-
from the late stage to the planning 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 most ancient 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, the skeletons of birds became lighter, and the toothy jaws were replaced by a toothless beak. They developed a "wide sternum, to which the powerful muscles necessary for flight were attached. All these changes made it possible to improve the structure of the bird's body, giving it an optimal structure for flight.
The first fossil find of Archeopteryx was a single feather, discovered in 1861. Soon, a whole skeleton of this animal (and with feathers!) was found in the same area. Since then, six fossilized skeletons of Archeopteryx have been discovered, some complete and others only fragmentary. The last such find dates back to 1988.

Age of dinosaurs.

The very first dinosaurs appeared over 200 million years ago. Over the 140 million years of their existence, they have evolved into a wide variety of species. Dinosaurs spread across all continents and adapted to life in a wide variety of habitats, although none of them lived in holes, did not climb trees, did not fly or swim. Some dinosaurs were no bigger than squirrels. Others weighed more than fifteen adult elephants combined. Some waddled heavily on all fours. Others ran faster on two legs than Olympic sprint champions.
65 million years ago, all dinosaurs suddenly became extinct. However, before disappearing 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 were the prosauropods. Some of them evolved into the largest land animals of all time - sauropods ("lizards"). These were the "giraffes" of the dinosaur world. They probably spent all their time eating leaves from the tops of trees. To provide vital energy for such a huge body, an incredible amount of food was required. Their stomachs were capacious digestive containers, continuously processing mountains of plant food.
Later, many varieties of small, swift-footed dinos appeared.
saurs - the so-called hadrosaurs. These were the "gazelles" of the dinosaur world. They plucked the undersized vegetation with their horny beaks and then chewed it up with strong molars.
The largest family of large carnivorous dinosaurs were the megalosaurids, or "huge lizards". The Megalosaurid was a ton-weight monster with huge, sharp, saw-toothed teeth that it used to tear through the flesh of its victims. Based on some of the fossilized footprints, his toes were pointing inward. It may have waddle like a giant duck, swinging its tail from side to side. Megalosaurids inhabited all regions of the globe. Their fossils 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 a fragile constitution. And later megalosaurids became truly bipedal monsters. Their hind legs ended in three fingers armed with powerful claws. Muscular forelimbs helped in hunting large herbivorous dinosaurs. The sharp claws no doubt left horrific lacerations in the flank of the surprised prey. The powerful muscular neck of the predator allowed him to thrust his dagger-shaped fangs deep into the body of the prey with terrible force and pull out huge pieces of still warm meat from it.

In the Jurassic period, flocks of allosaurs robbed 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.

Jurassic period the most famous of all periods of the Mesozoic era. Most likely, such fame Jurassic period acquired thanks to the film "Jurassic Park".

Jurassic period tectonics:

At first jurassic the single supercontinent Pangea began to disintegrate into separate continental blocks. Shallow seas formed between them. Intense tectonic movements at the end Triassic and at the beginning jurassic periods contributed to the deepening of large bays, which gradually separated Africa and Australia from Gondwana. The gulf between Africa and America deepened. Depressions formed in Eurasia: German, Anglo-Paris, West Siberian. The Arctic Sea flooded the northern coast of Laurasia. It is thanks to this that the climate of the Jurassic period became more humid. In the Jurassic the outlines of the continents begin to form: Africa, Australia, Antarctica, North and South America. And although they are located differently than now, they formed precisely in Jurassic period.

This is how the Earth looked at the end of the Triassic - the beginning jurassic
about 205 - 200 million years ago

This is how the Earth looked at the end of the Jurassic period, about 152 million years ago.

Climate and vegetation of the Jurassic period:

Volcanic activity of the end of the Triassic - the beginning jurassic caused the transgression of the sea. The continents separated and the climate in Jurassic period became wetter than in the Triassic. In place of the deserts of the Triassic period, in Jurassic period lush vegetation grew. Huge areas were covered with lush vegetation. Forests jurassic mainly consisted of ferns and gymnosperms.
Warm and humid climate jurassic contributed to the violent development of the plant world of the planet. Ferns, conifers, and cycads formed extensive marshy forests. Araucaria, arborvitae, cicadas grew on the coast. Ferns and horsetails formed vast forest areas. At the beginning jurassic, about 195 million years ago throughout the northern hemisphere, the vegetation was rather monotonous. But already starting from the middle of the Jurassic, about 170-165 million years ago, two (conditional) plant belts were formed: northern and southern. Ginkgo and herbaceous ferns predominated in the northern vegetation belt. AT Jurassic period Ginkgoaceae were very widespread. Groves of ginkgo trees grew throughout the belt.
In the southern vegetation belt, cycads and tree ferns predominated.
ferns jurassic and today are preserved in some corners of the wild. Horsetails and club mosses almost did not differ from modern ones. Places of growth of ferns and cordaites jurassic now occupied by tropical forests, consisting mainly of cycads. Cycads - a class of gymnosperms that prevailed in the green cover of the Earth jurassic. Now they are found here and there in the tropics and subtropics. Dinosaurs roamed under the canopy of these trees. Outwardly, 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.
AT Jurassic period ginkgo trees are 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 during the Jurassic period. coniferous forests jurassic were similar to modern ones.

land animals Jurassic:

Jurassic period Dawn of the Age of Dinosaurs. It was the violent development of vegetation that contributed to the emergence of many species of herbivorous dinosaurs. The growth in the number of herbivorous dinosaurs gave impetus to the growth in the number of predators. Dinosaurs settled all over the land and lived in forests, lakes, swamps. The range of differences between them is so great that family ties between them are established with great difficulty. Diversity of dinosaur species Jurassic period it was great. They could be the size of a cat or a chicken, or they could reach the size of huge whales.

One of the fossils jurassic combining features of birds and reptiles is archeopteryx, or the first bird. For the first time, his skeleton was discovered in the so-called lithographic slates 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. Archeopteryx still flew rather poorly (planned from tree to tree), and was about 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, they were preserved only in hoatzin chicks).

Jurassic Sky Kings:

AT Jurassic period winged lizards - pterosaurs reigned supreme in the air. They appeared as early as the Triassic, but their heyday fell on Jurassic period Pterosaurs were represented by two groups pterodactyls and rhamphorhynchus .

Pterodactyls in most cases were tailless, different in size - from the size of a sparrow to a crow. They had wide wings and a narrow skull extended 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 in rocks. The skin of pterodactyls was wrinkled and bare. They ate mainly fish or carrion, sometimes sea lilies, mollusks, and insects. In order to take off, pterodactyls had to jump off rocks or trees.

AT Jurassic period the first birds appear, or something in between birds and lizards. Creatures that appeared in Jurassic period and possessing the properties of lizards and modern birds are called Archeopteryx. The first birds are Archeopteryx, the size of a dove. Archeopteryx lived in forests. They fed mainly on insects and seeds.

But Jurassic period is not limited to animals alone. Thanks to climate change and the rapid development of flora jurassic, the evolution of insects accelerated dramatically, and as a result, the Jurassic landscape eventually filled with an endless buzz and crackle, which were emitted by many new types of insects, crawling and flying everywhere. Among them were the predecessors of modern ants, bees, earwigs, flies and wasps..

Masters of the seas of the Jurassic period:

As a result of the split of Pangea, in Jurassic period, new seas and straits were formed, in which new types of animals and algae developed.

Compared to the Triassic, Jurassic period the population of the seabed has changed a lot. Bivalves displace brachiopods from shallow waters. Brachiopod shells are replaced by oysters. Bivalve molluscs fill all the vital niches of the seabed. Many stop collecting food from the ground and move on to pumping water with the help of gills. In warm and shallow seas jurassic other important events took place. AT Jurassic period a new type of reef communities is emerging, approximately the same as that which exists now. It is based on six-ray corals that appeared in the Triassic. The resulting giant coral reefs have sheltered numerous ammonites and new varieties of belemnites (old relatives of today's octopuses and squids). Also, many invertebrates settled in them, such as sponges and bryozoans (sea mats). Gradually, fresh sediments accumulated on the seabed.

On land, in lakes and rivers jurassic There were many different types of crocodiles, widely settled around 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 it easier to swim. Tail fins allowed them to reach greater speed in water than on land. New species of sea turtles have also appeared.

All Jurassic Dinosaurs

Herbivorous dinosaurs: