An enceclopedic short information on the Jurassic period. Jurassic period

The Jurassic is the middle of the 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 ruled everywhere: in water, on land and in the air.
This period was named after the mountain range in Europe. The Jurassic period began about 208 million years ago. This period was more revolutionary than the Triassic. This revolutionism consisted of those estates that occurred with the earth's crust, because it was during the Jurassic period that the continent of Pangea began to diverge. The climate has since become warmer and more humid. In addition, the water level in the world's oceans began to rise. All this gave great opportunities for animals. Due to the fact that the climate became more favorable, plants began to appear on land. And in shallow waters, corals began to appear.

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. There were only deserts all around. But later, heavy rains began to saturate them with moisture. And the world became greener, lush vegetation began to bloom.
Ferns, conifers and cicadas formed vast swampy forests. Araucaria, thuja, and cicadas grew on the coast. Ferns and horsetails formed vast forests. At the beginning of the Jurassic period, about 195 million years ago. vegetation was fairly uniform throughout the northern hemisphere. 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. In the northern vegetation belt, ginkgo and herbaceous ferns prevailed. In the Jurassic period, ginkgoids were very widespread. Groves of ginkgo trees grew all over the belt.

The southern plant belt was dominated by cicada and tree ferns.
Jurassic ferns are preserved in some corners of the wild today. Horsetails and moss did not differ much from modern ones. The habitats of ferns and kordaites of the Jurassic period are now occupied by tropical forests, consisting mainly of sagavniks. Cycads are a class of gymnosperms that predominated in the green cover of the Jurassic Earth. Now they are found here and there in the tropics and subtropics. Dinosaurs roamed under the shade of these trees. Outwardly, cycads are so similar to low (up to 10-18 m) palms that they were even initially identified as palms in the plant system.

In the Jurassic period, ginkgoes are also common - deciduous (which is unusual for gymnosperms) trees with an oak-like crown and small fan-shaped leaves. To this day, only one species has survived - ginkgo biloba. The first cypress and, possibly, spruce trees appear precisely in the brisk period. Jurassic coniferous forests were similar to modern ones.

During the Jurassic period, a temperate climate was established on Earth. Even the arid zones were rich in vegetation. These conditions were ideal for dinosaurs to reproduce, including lizards and ornithischids.

The lizards moved on four legs, had five toes on their feet, and ate plants. Most of them had long necks, small heads, and long tails. They had two brains: one small - 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 the Jurassic lakes, fed on aquatic vegetation. Brachiosaurus needed at least half a ton of green mass every day.
Diplodocus is the oldest reptile, its length was 28 m. It had a long thin neck and a long thick tail. Like brachiosaurus, the diplodocus moved on four legs, the hind legs were longer than the front ones. Diplodocus spent most of its life in swamps and lakes, where it grazed and escaped from predators.

The Brontosaurus was relatively tall, with a large hump on its back and a thick tail. Chisel-shaped small teeth were densely located on the jaws of a small head. Brontosaurus lived in swamps, on the shores of lakes. Brontosaurus weighed about 30 tons and exceeded 20 and in length. The lizard-footed dinosaurs (sauropods) were the largest land animals still known. They were all herbivorous. Until recently, paleontologists believed that such heavy creatures were forced to spend most of their lives in the water. It was believed that on land, his shin bones would "break" under the weight of the colossal carcass. However, the findings of recent years (in particular, footprints) indicate that sauropods preferred to wander in shallow water, they also entered on solid ground. In relation to body size, brontosaurs had extremely small brains, weighing no more than a pound. In the region of the sacral vertebrae of the brontosaurus, there was an expansion of the spinal cord. Much larger than the brain, it controlled the muscles of the hind limbs and tail.

Avian dinosaurs are subdivided into bipeds and tetrapods. Different in size and appearance, they fed mainly on vegetation, but predators also appear among them.

Stegosaurs are herbivores. Stegosaurs are especially abundant in North America, from which 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 is massive, although the stegosaurus moved on four legs, its forelimbs were much shorter rear. On the back, large bony plates stood 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, accordingly, a tiny brain, a little more than a 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-like jaws.

In the Jurassic period, flying lizards first appear. They flew with the help of 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 tubular bones. The extremely elongated outer fifth toe of the forelimbs had four joints. The first finger looked like a small bone or was completely absent. The second, third and fourth fingers consisted of two, less often three bones and had claws. The hind limbs were quite well developed. They had sharp claws at their ends. The skull of flying lizards was relatively large, usually elongated and pointed. In old lizards, the cranial bones fused together and the skulls became similar to the skulls of birds. The intermaxillary bone sometimes grew into an elongated toothless beak. Toothed dinosaurs 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 to catch and hold on to their prey. The vertebral column of animals consisted of 8 cervical, 10-15 dorsal, 4-10 sacral and 10-40 caudal vertebrae. The ribcage was wide and had a high keel. The shoulder blades were long, the pelvic bones were fused. The most typical representatives of flying dinosaurs are pterodactyl and ramphorhynchus.

In most cases, pterodactyls were tailless, varying in size - from the size of a sparrow to a crow. They had wide wings and a narrow skull extended forward with few 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 the pterodactyls was wrinkled and bare. They ate mainly fish, sometimes sea lilies, molluscs, insects. In order to take off, pterodactyls had to jump off rocks or trees.
Rumphorhynchians had long tails, long narrow wings, and a large skull with numerous teeth. Long teeth of various sizes were bent forward. The tail of the lizard ended with a blade that served as a rudder. Rumphorhynchians could take off from the ground. They settled on the banks of rivers, lakes and seas, and ate insects and fish.

Flying lizards lived only in the Mesozoic era, and their heyday falls on the late Jurassic period. Their ancestors were, apparently, extinct ancient reptiles pseudosuchia. Long-tailed forms appeared earlier than short-tailed ones. They became extinct at the end of the Jurassic period.
It should be noted that flying lizards were not the ancestors of birds and bats. Flying lizards, birds and bats have originated and developed each in their own way, and there are no close family ties between them. The only common sign for them is the ability to fly. And although they all acquired this ability due to the change in their 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 bony plates. Elbow, metatarsus, hand and fingers differed little in shape from each other. About a hundred bone plates supported a 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 flourished 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. The more primitive Jurassic pliosaurs originate mainly from the territory of Europe. A plesiosaur from the Lower Jurassic, reaching a length of 3 m. These animals still often went ashore to rest. Plesiosaurs were not as agile in water as pliosaurs. This deficiency was compensated to a certain extent by the development of a long and very flexible neck, with the help of which plesiosaurs could seize 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.

In the Jurassic seas there were a lot of fish: bony, stingrays, sharks, cartilaginous, ganoid. They had an internal skeleton made of flexible cartilaginous tissue saturated with calcium salts: a dense bone scaly cover that protected them well from enemies, and jaws with strong teeth.
Among the invertebrates in the Jurassic seas were found ammonites, belemnites, sea lilies. However, in the Jurassic period, there were much fewer ammonites than in the Triassic. Jurassic ammonites differ from Triassic ones also in their structure, with the exception of phyloceras, which did not change at all during the transition from Triassic to Jurassic. Separate 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 flocks in the Jurassic seas. Along with small specimens, there were real giants - up to 3 m long.
Remnants of internal belemnite shells, known as “devil's fingers,” are found in Jurassic deposits.
In the seas of the Jurassic period, bivalve molluscs also developed significantly, especially those belonging to the oyster family. They start to form oyster banks. Sea urchins living on reefs undergo significant changes. Along with the round forms that have survived to this day, bilaterally symmetrical irregular-shaped hedgehogs lived. Their body was stretched out in one direction. Some of them had a jaw apparatus.

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

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


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 continent, 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 freely move from one continent to another, but they continued to spread freely throughout the southern supercontinent.
In the early Jurassic period, the climate throughout the earth was warm and dry. Then, when heavy rains began to saturate the ancient Triassic deserts with moisture, the world became greener again, with more lush vegetation. In the Jurassic landscape, horsetails and moss, which survived from the Triassic period, densely grew. Palm-shaped bennettites have also survived. In addition, there were many grios around. Vast forests of seed, common and tree ferns, as well as papo-rotnik-like cycads, spread from water bodies inland. Coniferous forests were still widespread. In addition to ginkgo and araucaria, the ancestors of modern cypresses, pines and mammoth trees grew in them.

Life in the seas.

When Pangea began to split, new seas and straits arose, in which new types of animals and algae took refuge. Gradually, fresh sediments accumulated on the seabed. They are home to many invertebrates such as sponges and bryozoans (marine mats). Other important events took place in warm and shallow seas. Giant coral reefs have formed there, hosting numerous ammonites and new varieties of belemnites (long-standing relatives of today's octopuses and squids).
On land, in lakes and rivers, many different species of crocodiles lived, widely spread across the globe. There were also saltwater crocodiles with long snouts and sharp teeth for fishing. Some species have even grown fins instead of legs to make it easier to swim. Their tail fins allowed them to develop faster in water than on land. New species of sea turtles have also appeared. Evolution also spawned many species of plesiosaurs and ichthyosaurs that rivaled new, fast-paced sharks and extremely agile bony fish.

This cycad is a living fossil. It is almost indistinguishable from its relatives who grew up on Earth in the Jurassic period. Nowadays, cycads are found only in the tropics. However, 200 million years ago, they were much more widespread.
Belemnites, live shells.

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 front 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 located 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 the fossil form of any other body part of belemnite, and usually it is he who falls into the hands of scientists. But sometimes they also find non-rostral fossils. The first such finds were at the beginning of the 19th 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 solution to this secret turned out to be extremely simple, as soon as more data was collected on the way of feeding the ichthyosaurs - the main enemies of the belemnites. Apparently, the strandless fossils were formed when an ichthyosaur, having swallowed a whole school of belemnites, belched out 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 squid, produced an ink liquid and used it to create a "smokescreen" when trying to escape from predators. Scientists have also found fossilized belemnite ink sacs (organs in which a supply of ink liquid was stored). One of the Victorian scholars, William Buckland, even managed to extract from fossil inkbags some ink, which he used to illustrate his book The Bridgewater Treatise.

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

A whole fossil belemnite (soft part plus rostrum) has not yet been found, although in the 70s. XX century in Germany, a rather ingenious attempt was made to fool the entire scientific world with a clever forgery. The whole fossils, allegedly mined in one of the quarries in southern Germany, were acquired by several museums at a very high price, before it was discovered that in all cases the calcareous rostrum was carefully glued to the soft parts of the belemnite fossils!
This famous photograph, taken in 1934 in Scotland, was recently declared to be a forgery. Nevertheless, for fifty years it fueled the enthusiasm of those who believed the Loch Ness monster to be a living plesiosaur.

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

Born for speed

The first ichthyosaurs appeared in the Triassic. These reptiles have perfectly 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 about 8 m in length, but many species did not exceed humans in size. They were excellent swimmers, feeding mainly on fish, squid and nautiloids. Although ichthyosaurs belonged to reptiles, according to their fossil remains, it can be assumed that they were viviparous, that is, they gave birth to ready-made offspring, like mammals. It is possible that ichthyosaur babies were born on the high seas, like whales.
Another group of carnivorous reptiles, also widespread in the Jurassic seas, are the plesiosaurs. Their long-necked varieties lived near the surface of the sea. Here they hunted schools of small fish with their flexible necks. The short-necked species, the so-called pliosaurs, preferred life at great depths. They ate ammonites and other shellfish. Some large pliosaurs seem to have also hunted smaller plesiosaurs and ichthyosaurs.

The ichthyosaurs looked like exact replicas 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 figured out that the spine of these animals was curved and had a vertical tail fin at its end (in contrast to the horizontal fins of dolphins and whales).
Life in the Jurassic air.

In the Jurassic, the evolution of insects sharply accelerated, and as a result, the Jurassic landscape over time was filled with an endless buzz and crackle, which published many new species of insects, crawling and flying all over the place. 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 newly emerged flowering plants.
Until this time, real flying animals were found only among insects, although attempts to master the air environment were observed in other creatures who 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" was in the Jurassic period. The 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. Some fossil pterosaurs have 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 thought that pterosaurs were a kind of "living glider" that hovered like vultures above the ground in currents of rising hot air. Perhaps they even glided over the ocean surface, drawn by the 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 a bird, while others dragged their bodies along the ground or slept in places of nesting 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 made it possible to make an even more curious discovery. Small hard spines on the tentacles of squid and other cephalopods, apparently, caused a lot of inconvenience to ichthyosaurs, since they were not digested and, accordingly, could not freely pass through their digestive system. As a result, the thorns 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 had swallowed at least 1,500 squid!
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 started with the fact that two-legged animals, the predecessors of birds, scattered 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 oolipe, the jumps, in turn, lengthened. The bird did not touch the ground for 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 maintain 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 way to flying 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 during planning it is pulled down by the force of gravity.

The first Archeopteryx fossil was discovered two years after the publication of Charles Darwin's Origin of Species. This important discovery was another confirmation of Darwin's theory that evolution occurs very slowly and that one group of animals gives rise to another, undergoing a series of successive transformations. 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 detailed this animal before it was discovered!
Step flight.

One scientist has proposed an extremely interesting theory. She describes a series of stages through which the "pioneers of aeronautics" had to go through the evolutionary process that eventually turned them into flying animals. According to this theory, once one of the groups of small reptiles, called pro-tropts, switched to an arboreal lifestyle. Perhaps the reptiles climbed the trees because it was safer there, or it was easier to get food, or it was more convenient to hide, sleep, and equip nests. The treetops were cooler than on the ground, and these reptiles developed warm-bloodedness and feathers for better thermal insulation. Any extra long feathers on the limbs came in handy - after all, they provided additional insulation and increased the surface area of ​​the wing-shaped "arms".
In turn, the soft, feathery forelimbs softened the impact on the ground when the animal lost its 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 nasty stage to the planning one was supposed to be 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 these, 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 wing. 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 off the ground using gusts of wind. In the process of evolution, the skeletons of birds became more and more lighter, and the toothy jaws were replaced by a toothless beak. They developed "a broad sternum, to which were attached powerful muscles necessary for flight. All these changes allowed to improve the structure of the bird's body, giving it an optimal structure for flight.
The first fossil record of Archeopteryx was a single feather, discovered in 1861. Soon a whole skeleton of this animal (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 the 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 have spread to all continents and adapted to life in a wide variety of habitats, although none of them lived in holes, climbed trees, did not fly or swim. Some dinosaurs were no larger than a squirrel. Others weighed more than fifteen adult elephants combined. Some were waddling heavily on four legs. Others ran on two legs faster than the Olympic champions in the sprint.
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 "account" of their life and their time.
The most common group of dinosaurs during the Jurassic period were the Prosauropods. Some of them evolved 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 tops of the trees. To provide such a huge body with vital energy, an incredible amount of food was required. Their stomachs were roomy digestive tanks that continuously processed mountains of plant food.
Later, many varieties of small swift-footed dinosaurs appeared.
Saurus - the so-called hadrosaurs. These were the "gazelles" of the dinosaur world. They nibbled on stunted vegetation with their horny beaks, and then chewed on it with strong molars.
The largest family of large carnivorous dinosaurs was the megalosaurids, or "huge lizards." Megalo-zavrid was a ton-weighted monster, with enormous, sharp teeth, like saws, with which it tore through the flesh of its victims. From some fossilized footprints, his toes were pointing inward. Perhaps he waddled like a giant duck, swinging his tail from side to side. Megalosaurids inhabited all areas of the globe. Their fossils have been found in places as far apart as North America, Spain and Madagascar.
The earliest species of this family were, apparently, relatively small animals of fragile constitution. And later megalosaurids became truly bipedal monsters. Their hind legs ended in three toes armed with powerful claws. The muscular forelimbs helped when hunting large herbivorous dinosaurs. The sharp claws no doubt left terrible lacerations in the side of the unaware victim. The powerful muscular neck of the predator allowed him with terrible force to thrust dagger-like fangs deep into the body of the prey and pull out huge pieces of still warm meat from it.

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

|
jurassic, jurassic movie
Jurassic period (Yura) - middle (second) period of the Mesozoic era. It began 201.3 ± 0.2 million years ago, ended 145.0 million years ago. Thus, it lasted for about 56 million years. A complex of sediments (rocks) corresponding to a given age is called Jurassic system... in different regions of the planet, these deposits differ in composition, genesis, and appearance.

For the first time, deposits of this 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.

• 1 Subdivision of the Jurassic system
  • 1.1 Geological events
  • 1.2 Climate
  • 1.3 Vegetation
  • 1.4 Marine organisms
  • 1.5 Land animals
• 2 Notes
• 3 Literature
• 4 References

Division of the Jurassic System

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

system	the Department	tier	Age, million years ago
chalk	Lower	Berriasian	less
	Upper (malm)	Titonian	145,0-152,1
		Kimmeridge	152,1-157,3
		Oxford	157,3-163,5
	Average (dogger)	Callovian	163,5-166,1
		Batsky	166,1-168,3
		Bayossky	168,3-170,3
		Aalensky	170,3-174,1
	Lower (lias)	Toarsky	174,1-182,7
		Plinsbach	182,7-190,8
		Sinemurskiy	190,8-199,3
		Gettangian	199,3-201,3
Triassic	Upper	Rhetic	more
Subsections are given according to IUGS as of January 2015

Geological events

213-145 million years ago, a single supercontinent Pangea began to disintegrate 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 it was arid in the equatorial region).

Vegetation

The drooping cycad (Cycas revoluta) is one of the cycads that grow in our time
Ginkgo biloba (Ginkgo biloba). Botanical illustration from the book of Siebold and Zuccarini Flora Japonica, Sectio Prima, 1870

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

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

During the Jurassic period, groves of gingkos grew throughout the then temperate zone. Ginkgoes are deciduous (unusual for gymnosperms) trees with an oak-like crown and small fan-shaped leaves. To this day, only one species has survived - ginkgo biloba.

Conifers were very diverse, similar to modern pines and cypresses, which flourished at that time not only in the tropics, but had already mastered the temperate zone. The ferns gradually disappeared.

Marine organisms

Leedsichtis and Liopleurodon

Compared to the Triassic, the population of the seabed has changed greatly. Bivalve molluscs displace brachiopods from shallow waters. Brachiopod shell rocks are replaced by oyster ones. Bivalve molluscs fill all 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 is now. It is based on the six-rayed corals that appeared in the Triassic.

Land animals

Reconstruction of Archeopteryx,
Oxford University Museum

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 found in the so-called lithographic shale 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. Archeopteryx was still flying rather poorly (he planned from tree to tree), and was about the size of a crow. Instead of a beak, it had a pair of toothed, albeit weak jaws. On its wings there were free fingers (of modern birds, they are preserved only in the chicks of goatsins).

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. In the Jurassic, mammals were divided into monotremes, marsupials and placentals.

Dinosaurs (English Dinosauria, from ancient Greek δεινός - terrible, terrible, dangerous and σαύρα - lizard, lizard), dominated on land, lived in forests, lakes, swamps. The range of differences between them is so great that family ties between their species are established with great difficulty. There were dinosaurs ranging in size from cat to whale. Different types of dinosaurs could move on two or four limbs. Among them were both carnivores and herbivores. Of the latter, sauropods flourished in the Jurassic period - diplodocus, brachiosaurs, apatosaurs, camarasaurs. The sauropod was hunted by other dinosaur dinosaurs, namely the large theropods.

Brachiosaurus

Ceratosaurus

Pseudotribos

Notes (edit)

1. International Stratigraphic Scale (January 2013 version) on the website of the International Commission on Stratigraphy

Literature

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

Links

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

←	P a l e O s O th	Mesozoic (251-65 million years ago)			TO a th n O s O th	→
←		Triassic (251-199)	(199-145)	Cretaceous period (145-65)		→

Jurassic period, Jurassic period 2018, Jurassic period cinema, Jurassic period continents, Jurassic period cartoon, Jurassic period watch, Jurassic period watch online, Jurassic period clash is inevitable, Jurassic period film, Jurassic period part 3

Jurassic Information About

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 on 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 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 lasted 200-150 million years ago. A rather hot climate was characteristic of that time. Dense vegetation, the absence of snow and cold weather led to the fact that life on earth was everywhere: on land, in the air and in water. The increased humidity of the air led to the violent growth of plants, which became food for herbivores, which grew to gigantic proportions. But they, like smaller animals, served as food for predators, the variety of which is quite interesting.

The sea level was significantly higher than it is now, and the favorable climate has led to a rich variety of life in the water. The shallow waters were teeming 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 - the pterosaurs - have taken over the sky. But in the same period, the ancestors of modern birds appeared, in whose wings there were no leather membranes, but feathers originated.

Herbivorous dinosaurs

The Jurassic era gave the world many large reptiles. Most of them reached fantastically gigantic proportions. The largest dinosaur of the Jurassic period, the diplodocus, inhabited 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 in order for small stones to grind the vegetation and bark of trees in the stomach of the animal. After all, the teeth of a diplodocus were very small, no larger than a human nail, and could not help the animal thoroughly chew plant food.

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 ate the leaves of conifers and cycads. Such a giant easily absorbed almost half a ton of plant food a day and preferred to settle near water bodies.

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

jurassic

A variety of herbivores leads to the emergence of a large number of predators, because nature always keeps balance. The largest and bloodthirsty dinosaur of the Jurassic period - Allosaurus, reached a length of almost 11 meters, and was 4 meters high. This 2-ton predator hunted in the USA and Portugal and earned the title of the fastest runner.

He ate not only small animals, but, joining in groups, he hunted even very large prey, for example, apatosaurs or camarasaurs. To do this, a sick or young individual was beaten off from the herd by common efforts, and then collectively devoured.

The 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 ridges 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 attack an animal much larger than it. Great maneuverability and speed allowed Dilophosaurus to catch even a fairly fast and miniature Scutellosaurus.

Marine life

The land is not the only place that was inhabited by dinosaurs, and the Jurassic world in water was also diverse and multifaceted. A prominent representative of that era was the plesiosaurus. This waterfowl predatory lizard had a neck length and reached a length of up to 18 meters. The skeletal structure with a short but wide enough tail and powerful fins resembling oars allowed this predator to develop high speed and reign in the depths of the sea.

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

Kings of the sky

By the end of the Jurassic period, the heavenly heights were conquered by small predators, pterodactyls. 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 rather 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 its 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: dinosaurs were far from the only population of the Earth at that time. 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 were teeming with many species of fish such as sharks, rays and other cartilaginous and bony fish. they are belemnites, they were the lower link of the food chain, but their large population supported life in the water space. During this period, crustaceans such as barnacles, leaf-footed and freshwater sponges appear.

Intermediate

The Jurassic period is notable for the appearance of the ancestors of birds. Of course, Archeopteryx did not look so much like a modern bird, it was, rather, a miniraptor with feathers.

But a later ancestor, aka Longipteryx, already resembled a modern kingfisher. Although birds for that era are quite a rare phenomenon, they give rise to a new round of evolution of the animal world. The dinosaurs of the Jurassic period (photo presented above) have become extinct long ago, but even now, looking at the remains of such giants, you are in awe of these giants.

And Switzerland. The beginning of the Jurassic period by the radiometric method is determined at 185 ± 5 million years, the end - at 132 ± 5 million years; the total duration of the period is about 53 million years (according to 1975 data).

The Jurassic system in its modern volume was identified in 1822 by the German scientist A. Humboldt under the name "Jurassic formation" in the Jura mountains (Switzerland), the Swabian and Franconian Alb (). The Jurassic deposits were first established on the territory by the German geologist L. Buch (1840). The first scheme of their stratigraphy and subdivision was developed by the Russian geologist K.F.Rul'e (1845-49) in the Moscow region.

Subdivisions... All the main subdivisions of the Jurassic system, later included in the general stratigraphic scale, are identified in the territory of Central Europe and Great Britain. The division of the Jurassic system into divisions was proposed by L. Bukh (1836). The foundations of the layering of the Jurassic were laid by the French geologist A. d "Orbigny (1850-52). The German geologist A. Oppel was the first to produce (1856-58) a detailed (zonal) subdivision of the Jurassic deposits. See Table.

Most foreign geologists attribute the Callovian Stage to the middle section, citing the priority of the three-term division of the Jurassic (black, brown, white) L. Bukha (1839). The Tithonian Stage is distinguished in the sediments of the Mediterranean Biogeographic Province (Oppel, 1865); for the northern (boreal) province, its equivalent is the Volgian stage, first identified in the Volga region (Nikitin, 1881).

general characteristics... Jurassic deposits are widespread on the territory of all continents and are present in the periphery, in parts of ocean depressions, forming the base of their sedimentary layer. By the beginning of the Jurassic period, two large continental massifs were distinguished in the structure of the earth's crust: Laurasia, which included the platforms and Paleozoic folded regions of North America and Eurasia, and Gondwana, which united the platforms of the Southern Hemisphere. They were separated by the Mediterranean geosynclinal belt, which was the Tethys oceanic basin. The opposite hemisphere of the Earth was occupied by the Pacific Ocean depression, along the edges of which the geosynclinal regions of the Pacific geosynclinal belt developed.

In the Tethys oceanic basin during the entire Jurassic period, there was an accumulation of deep-water siliceous, clayey and carbonate deposits, accompanied by local manifestations of submarine tholeiite-basalt volcanism. The wide southern passive margin of the Tethys was an area of ​​accumulation of shallow-water carbonate deposits. On the northern outskirts, which in different places and at different times had both active and passive nature, the composition of the deposits is more variegated: sandy-clayey, carbonate, in places flysch, sometimes with the manifestation of calcareous-alkaline volcanism. The geosynclinal regions of the Pacific belt developed in the regime of active margins. They are sharply dominated by sandy-argillaceous sediments, many siliceous, volcanic activity was very active. The main part of Laurasia in the early and middle Jurassic was dry land. In the Early Jurassic, marine transgressions from geosynclinal belts captured only the territories of Western Europe, the northern part of Western Siberia, the eastern edge of the Siberian platform, and in the Middle Jurassic, the southern part of the East European. At the beginning of the Late Jurassic, the transgression reached its maximum, spreading to the western part of the North American platform, the East European, all of Western Siberia, the Ciscaucasia and the Trans-Caspian. Gondwana remained dry land throughout the Jurassic period. Marine transgressions from the southern outskirts of Tethys captured only the northeastern part of the African and northwestern part of the Hindustan platforms. The seas within Laurasia and Gondwana were vast, but shallow epicontinental basins, where thin sandy-clayey accumulated, and in the Late Jurassic, in the areas adjacent to Tethys, carbonate and lagoon (gypsum and saline) sediments. In the rest of the territory, Jurassic deposits are either absent or are represented by continental sandy-clayey, often coal-bearing strata, filling individual depressions. The Pacific Ocean in the Jurassic period was a typical oceanic depression, where thin carbonate-siliceous sediments and covers of tholeiitic basalts, preserved in the western part of the depression, accumulated. At the end of the Middle - beginning of the Late Jurassic, the formation of "young" oceans begins; the opening of the Central Atlantic, the Somali and North Australian basins of the Indian Ocean The Amerasian basin of the Arctic Ocean, thereby beginning the process of the dismemberment of Laurasia and Gondwana and the separation of modern continents and platforms.

The end of the Jurassic period is the time of the manifestation of the Late Cimmerian phase of the Mesozoic folding in the geosynclinal belts. In the Mediterranean belt, folding movements were manifested in places at the beginning of the Bajocian, in the Pre-Callovian time (Crimea, Caucasus), at the end of the Jurassic (Alps, etc.). But they reached a special scope in the Pacific belt: in the Cordillera of North America (Nevada folding), and the Verkhoyansk-Chukotka region (Verkhoyansk folding), where they were accompanied by the introduction of large granitoid intrusions, and completed the geosynclinal development of the regions.

The organic world of the Earth in the Jurassic period had a typical Mesozoic appearance. Among marine invertebrates, cephalopods (ammonites, belemnites) flourish, bivalves and gastropods, six-rayed corals, and "irregular" sea urchins are widespread. Among vertebrates in the Jurassic period, reptiles (lizards) predominate sharply, reaching gigantic sizes (up to 25-30 m) and a great variety. There are known terrestrial herbivorous and carnivorous lizards (dinosaurs), marine swimming (ichthyosaurs, plesiosaurs), flying dinosaurs (pterosaurs). Fish are widespread in water basins; the first (toothy) birds appear in the air in the Late Jurassic. Mammals, represented by small, still primitive forms, are not widespread. The vegetation cover of the Jurassic land is characterized by the maximum development of gymnosperms (cicadas, bennetite, ginkgo, conifers), as well as ferns.