Encyclopedic short information about the Jurassic period. Jurassic system (period) How many years ago was the Jurassic period

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

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

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

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

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

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

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

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

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

Flying lizards first appeared in the Jurassic period. They flew using a leathery shell stretched between the long finger of the hand and the bones of the forearm. Flying lizards were well adapted to flight. They had light tube-shaped bones. The extremely elongated outer fifth digit of the forelimbs consisted of four joints. The first finger looked like a small bone or was completely absent. The second, third and fourth fingers consisted of two, rarely three bones and had claws. The hind limbs were quite developed. There were sharp claws at their ends. The skull of flying lizards was relatively large, usually elongated and pointed. In old lizards, the cranial bones fused and the skulls became similar to the skulls of birds. The premaxillary bone sometimes grew into an elongated toothless beak. Toothed lizards had simple teeth and sat in recesses. The largest teeth were in the front. Sometimes they stuck out to the side. This helped the lizards catch and hold prey. The spine of animals consisted of 8 cervical, 10-15 dorsal, 4-10 sacral and 10-40 caudal vertebrae. The chest was wide and had a high keel. The shoulder blades were long, the pelvic bones were fused. The most typical representatives of flying lizards are pterodactyl and rhamphorhynchus.

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

Flying lizards lived only in the Mesozoic era, and their heyday occurred in the Late Jurassic period. Their ancestors were, apparently, extinct ancient reptiles pseudosuchians. Long-tailed forms appeared earlier than short-tailed ones. At the end of the Jurassic period they became extinct.
It should be noted that flying lizards were not the ancestors of birds and bats. Flying lizards, birds and the bats each originated and developed in its own way, and there are no close ones between them family ties. The only thing they have in common is the ability to fly. And although they all acquired this ability due to changes in the forelimbs, the differences in the structure of their wings convince us that they had completely different ancestors.

The seas of the Jurassic period were inhabited by dolphin-like reptiles - ichthyosaurs. They had long head, sharp teeth, big eyes surrounded by a ring of bone. The length of the skull of some of them was 3 m, and the length of the body was 12 m. The limbs of ichthyosaurs consisted of bone plates. The elbow, metatarsus, hand and fingers differed little from each other in shape. About a hundred bone plates supported the wide flipper. The shoulder and pelvic girdles were poorly developed. There were several fins on the body. Ichthyosaurs were viviparous animals.

Plesiosaurs lived alongside ichthyosaurs. Appearing in the Middle Triassic, they reached their peak already in the Lower Jurassic; in the Cretaceous they were common in all seas. They were divided into two main groups: long-necked with a small head (plesiosaurs proper) and short-necked with a rather massive head (pliosaurs). The limbs turned into powerful flippers, which became the main organ of swimming. More primitive Jurassic pliosaurs come mainly from Europe. A plesiosaur from the Lower Jurassic reached a length of 3 m. These animals often went ashore to rest. Plesiosaurs were not as agile in water as pliosaurs. This deficiency was to a certain extent compensated for by the development of a long and very flexible neck, with the help of which plesiosaurs could grab prey with lightning speed. They ate mainly fish and shellfish.
During the Jurassic period, new genera of fossil turtles appeared, and at the end of the period, modern turtles appeared.
Tailless frog-like amphibians lived in fresh water bodies.

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

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

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

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



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

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

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

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

Intense volcanism and mountain-building processes determined the formation of the Verkhoyansk fold system. The formation of the Andes and Cordilleras continued. Warm sea currents reached Arctic latitudes. The climate became warm and humid. This is evidenced by the significant distribution of coral limestones and the remains of thermophilic fauna and flora. Very few deposits of dry climates are found: lagoonal gypsum, anhydrites, salts and red sandstones. The cold season already existed, but it was characterized only by a decrease in temperature. There was no snow or ice.

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

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

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

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

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

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

The lush vegetation of the Jurassic period contributed to the widespread distribution of reptiles. Dinosaurs have evolved significantly. Among them, lizard-hatched and ornithischian are distinguished. Lizards moved on four legs, had five toes on their feet, and ate plants. Most of them had a long neck, small head and long tail. They had two brains: one small one in the head; the second is much larger in size - at the base of the tail.

The largest of the Jurassic dinosaurs was the Brachiosaurus, reaching a length of 26 m and weighing about 50 tons. It had columnar legs, a small head, and a thick long neck. Brachiosaurs lived on the shores of Jurassic lakes and fed on aquatic vegetation. Every day, the brachiosaurus needed at least half a ton of green mass.

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

Brontosaurus was relatively tall, had a large hump on its back and a thick tail. Its length was 18 m. The vertebrae of the brontosaurus were hollow. Chisel-shaped small teeth were densely located on the jaws of the small head. The brontosaurus lived in swamps and on the shores of lakes.

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Jurassic period, Jurassic period movie
Jurassic period (Yura) - middle (second) period of the Mesozoic era. Began 201.3 ± 0.2 million years ago, ended 145.0 million years ago. Thus it continued 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); This is where the name of the period came from. The deposits of that time are quite diverse: limestones, clastic rocks, shales, igneous rocks, clays, sands, conglomerates, formed in a variety of conditions.

• 1 Jurassic Division
  • 1.1 Geological events
  • 1.2 Climate
  • 1.3 Vegetation
  • 1.4 Marine organisms
  • 1.5 Land animals
• 2 Notes
• 3 Literature
• 4 Links

Jurassic System Division

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

system	Department	tier	Age, million years ago
Chalk	Lower	Berriasian	less
	Upper (malm)	Tetonian	145,0-152,1
		Kimmeridge	152,1-157,3
		Oxford	157,3-163,5
	Average (dogger)	Callovian	163,5-166,1
		Bathian	166,1-168,3
		Bayocian	168,3-170,3
		Aalensky	170,3-174,1
	Lower (lias)	Toarsky	174,1-182,7
		Pliensbachian	182,7-190,8
		Sinemyursky	190,8-199,3
		Hettangian	199,3-201,3
Triassic	Upper	Rhetic	more
Subsections are given in accordance with IUGS as of January 2015

Geological events

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

Climate

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

Vegetation

Drooping cycad (Cycas revoluta) is one of the cycads growing today
Ginkgo biloba (Ginkgo biloba). Botanical illustration from Siebold and Zuccarini's book Flora Japonica, Sectio Prima, 1870

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

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

During the Jurassic period, groves of gingkovic trees grew throughout the then temperate zone. Ginkgos are deciduous (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 conifers were very diverse, similar to modern pines and cypresses, which flourished at that time not only in the tropics, but had already mastered temperate zone. The ferns gradually disappeared.

Marine organisms

Leedsichthys and Liopleurodon

Compared to the Triassic, the population of the seabed has changed greatly. Bivalves push out brachiopods from shallow waters. Brachiopod shells are replaced by oysters. Bivalve mollusks fill all life niches of the seabed. Many stop collecting food from the ground and switch to pumping water using their gills. A new type of reef community is emerging, approximately the same as what exists now. It is based on six-rayed corals that appeared in the Triassic.

Land animals

Reconstruction of Archeopteryx,
Oxford University Museum

One of the fossil creatures that combines the characteristics of birds and reptiles is Archeopteryx, or the first bird. His skeleton was first discovered in the so-called lithographic shales in Germany. The discovery was made two years after the publication of Charles Darwin's On the Origin of Species and became a strong argument in favor of the theory of evolution. Archeopteryx still flew quite poorly (gliding from tree to tree), and was approximately the size of a crow. Instead of a beak, it had a pair of toothy, albeit weak, jaws. It had free fingers on its wings (of modern birds, only hoatzin chicks have them).

During the Jurassic period, small, furry, warm-blooded animals called mammals lived on Earth. They live next to dinosaurs and are almost invisible against their background. 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), dominant 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 a cat to a whale. Different types of dinosaurs could walk on two or four limbs. Among them were both predators and herbivores. Of the latter, the Jurassic period saw the heyday of sauropods - diplodocus, brachiosaurs, apatosaurs, and camarasaurs. Sauropods were hunted by other lizard-hipped dinosaurs, namely large theropods.

Brachiosaurus

Ceratosaurus

Pseudotribos

Notes

1. International Stratigraphic Chart (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 // encyclopedic Dictionary Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg, 1890-1907.
• Koronovsky N.V., Khain V.E., Yasamanov N.A. Historical geology: Textbook. - M.: Academy, 2006.
• Ushakov S.A., Yasamanov N.A. Continental drift and climates of the Earth. - M.: Mysl, 1984.
• Yasamanov N.A. Ancient climates of the Earth. - L.: Gidrometeoizdat, 1985.
• Yasamanov N.A. Popular paleogeography. - M.: Mysl, 1985.

Links

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

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

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Jurassic Period Information About

From 213 to 144 million years ago.
By the beginning of the Jurassic period, the giant supercontinent Pangea was in the process of active disintegration. There was still a single vast continent south of the equator, which was again called Gondwana. 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 unhindered throughout the southern supercontinent.
At the beginning of the Jurassic period, the climate throughout the Earth was warm and dry. Then, as heavy rains began to soak the ancient Triassic deserts, the world became greener again, with more lush vegetation. The Jurassic landscape was thick with horsetails and club mosses, which had survived from the Triassic period. Palm-shaped bennettites are also preserved. In addition, there were many grios around. Vast forests of seed, common and tree ferns, as well as fern-like cycads, spread from bodies of water inland. Were still common coniferous forests. In addition to ginkgo and araucaria, the ancestors of modern cypresses, pines and mammoth trees grew in them.

Life in the seas.

As Pangea began to break apart, new seas and straits emerged, in which new types of animals and algae found refuge. Gradually, fresh sediment accumulated on the seabed. They are home to many invertebrates, such as sponges and bryozoans (sea mats). Other events also occurred in warm and shallow seas. important events. 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, there lived many different types crocodiles, widely spread across the globe. There were also saltwater crocodiles with long snouts and sharp teeth for fishing. Some of their varieties even grew flippers instead of legs to make swimming more convenient. The tail fins allowed them to develop greater speed in the water than on land. New species of sea turtles have also appeared. Evolution also produced many species of plesiosaurs and ichthyosaurs, competing with new, fast-moving sharks and extremely agile bony fish.

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

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

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

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

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

Born for Speed

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

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

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

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

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

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

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

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

Age of Dinosaurs.

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

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

And was replaced by chalk, and had a duration of about 56 million years.

Geography and climate

During the Jurassic period, the supercontinent Pangea began to split into two separate continents:

• the northern part known as Laurasia (which eventually split into North America and Eurasia, opening up the basins to Atlantic Ocean, and the Gulf of Mexico)
• the southern part - Gondwanaland - drifted east (and eventually divided into Antarctica, Madagascar, India and Australia, and its western part formed Africa and South America).

This process of Pangea's separation, along with warmer global temperatures, allowed reptiles such as dinosaurs to diversify and dominate the Earth for long periods of time.

Plant life

During the Mesozoic era, plants developed the ability to lead a terrestrial lifestyle and not be limited only to the oceans. By the beginning of the Jurassic, life came from bryophytes, low-growing bryophytes and liverworts, which had no vascular tissue and were limited to wet, marshy areas.

Ginkgo trees

Ferns and gingaceae, which had roots and vascular tissue for transporting water and nutrients, and reproduced by spores, were the dominant plants of the Early Jurassic. Appeared during the Jurassic period new way plant propagation. Gymnosperms such as coniferous trees, have developed pollen that is distributed over long distances by the wind and pollinates female cones. This method of reproduction made it possible to significantly increase the number gymnosperms towards the end of the Jurassic period. Flowering plants did not evolve until the Cretaceous period.

Age of Dinosaurs

As depicted in the movie Jurassic Park, reptiles were the dominant animal life form during the Jurassic period. They overcame evolutionary obstacles that limited . Reptiles had strong, ossified skeletons with advanced muscular systems for support and movement of the body. Some of the largest animals that ever lived were the dinosaurs of the Jurassic period. Reptiles could also develop amniotic eggs that were incubated on land.

sauropods

Sauropods (lizard-footed dinosaurs) are herbivorous quadrupeds with long necks and heavy tails. Many sauropods, such as brachiosaurs, were huge. Representatives of some genera had a body length of about 25 m, and weight ranged from 50-100 tons, which makes them the largest land animals that have ever existed on Earth. Their skulls were relatively small, with nostrils raised high towards the eyes. Such small skulls meant very small brains. Despite their small brains, this group of animals flourished during the Jurassic period and had a wide geographic distribution. Sauropod fossils have been found on every continent except Antarctica. Other famous dinosaurs The Jurassic includes stegosaurs and flying pterosaurs.

Carnosaurs were one of the main predators of the Mesozoic era. The genus Allosaurus was one of the most widespread carnosaurs in North America. They are similar to later tyrannosaurs, although studies have shown that they have little in common. Allosaurs had strong hind limbs, heavy front legs and long jaws.

Early mammals

Adelobazilevs

Dinosaurs may have been the dominant land animals, but they were not the only fauna. Early mammals were mostly very small herbivores or insectivores, and did not compete with larger ones. large reptiles. Adelobasileus is a predatory ancestor of mammals. He had a special structure of the inner ear and jaws. This animal appeared at the end of the Triassic period.

In August 2011, scientists from China announced the discovery of Yuramaya. This tiny mid-Jurassic animal caused excitement among scientists because it was a clear ancestor of placental mammals, indicating that mammals evolved much earlier than previously thought.

Sea life

Plesiosaur

The Jurassic period was also very diverse. The largest sea ​​predators there were plesiosaurs. These carnivorous marine reptiles typically had wide bodies and long necks with four flipper-shaped limbs.

Ichthyosaur is a marine reptile that was most common in the early Jurassic period. Because some fossils have been found with smaller individuals of their species inside their bodies, it is suggested that these animals may have been among the first to experience internal pregnancy and give birth to live young.

Cephalopods were also widespread during the Jurassic period and included the ancestors of modern squids. Among the most beautiful fossils sea ​​life Spiral-shaped shells of ammonites can be distinguished.