Jurassic period, description of the Jurassic period, dinosaurs of the Jurassic period, lizards of the Jurassic period. Geological period. Neogene period. Triassic. Jurassic period Jurassic period main events

160 million years ago, the rich plant world provided food for the giant sauropods that had emerged by this time, and also provided shelter for a huge number of small mammals and dinosaurs. At this time, conifers, ferns, horsetails, tree ferns and cycads were widespread.

A distinctive feature of the Jurassic period was the appearance and flourishing of giant lizard-hipped herbivorous dinosaurs, sauropods, the largest land animals that ever existed. Despite their size, these dinosaurs were quite numerous.

Their fossilized remains are found on all continents (except Antarctica) in rocks from the Early Jurassic to the Late Cretaceous, although they were most common in the second half of the Jurassic. At the same time, sauropods reach their most large sizes. They survived until the Late Cretaceous, when the huge hadrosaurs ("duck-billed dinosaurs") began to dominate the terrestrial herbivores.

Externally, all sauropods looked similar friend on a friend: with an extremely long neck, even more long tail, a massive but relatively short body, four column-like legs and a relatively small head. In different species, only body position and proportions could change individual parts. For example, such sauropods of the Late Jurassic period as brachiosaurs (Brachiosaurus - “shouldered lizard”) were higher in the shoulder girdle than in the pelvic girdle, while contemporary diplodocus (Diplodocus - “double appendage”) were significantly lower, and at the same time their hips rose above their shoulders. Some sauropod species, such as Camarasaurus ("chamber lizard"), had a relatively short neck, only slightly longer than the body, while others, such as diplodocus, had a neck more than twice as long as the body.

Teeth and diet

The external similarity of sauropods masks the unexpectedly wide diversity in the structure of their teeth and, consequently, in their feeding methods.

The Diplodocus skull helped paleontologists understand the feeding method of this dinosaur. The abrasion of the teeth indicates that he plucked leaves either from below or from above him.

Many books on dinosaurs used to mention the "small, thin teeth" of sauropods, but it is now known that the teeth of some of them, such as Camarasaurs, were massive and strong enough to grind even very hard plant food, while the long and thin ones Diplodocus's pencil-shaped teeth do appear unable to withstand the significant stress of chewing hard plants.

diplodocus (Diplodocus). Long neck allowed him to “comb” food from the highest coniferous plants. It is believed that Diplodocus lived in small herds and ate tree shoots.

In a study of diplodocus teeth carried out in last years in England, unusual wear on their side surfaces was discovered. This pattern of tooth wear provided the key to understanding how these huge animals could feed. Side surface The teeth could wear down only if something moved between them. Apparently, Diplodocus used its teeth to tear apart tufts of leaves and shoots, acting as a comb, while its lower jaw could move slightly back and forth. Most likely, when the animal divided the plants captured below into strips by moving its head up and back, the lower jaw was displaced back (the upper teeth were located in front of the lower ones), and when it pulled the branches of tall trees located above down and back, it pushed lower jaw forward (the lower teeth were in front of the upper teeth).

Brachiosaurus probably used its shorter, slightly pointed teeth to pluck only high-lying leaves and shoots, as its body's vertical orientation dictated longer front legs, made it difficult to feed on plants growing low above the soil.

Narrow specialization

Camarasaurus, somewhat smaller in size than the giants mentioned above, had a relatively short and thicker neck and most likely fed on leaves located at an intermediate height between the feeding levels of brachiosaurs and diplodocus. It had a tall, rounded and more massive skull compared to other sauropods, as well as a more massive and stronger lower jaw, indicating a better ability to grind hard plant food.

The details of the anatomical structure of sauropods described above show that within one ecological system (in the forests covering at that time most sushi) sauropods ate a variety of plant foods, extracting it in different ways at different levels. This division by feeding strategy and type of food, which can be seen in herbivore communities today, is called “tropical partitioning.”

Brachiosaurus reached more than 25 m in length and 13 m in height. Their fossilized remains and fossilized eggs are found in East Africa and North America. They probably lived in herds like modern elephants.

The main difference between today's herbivore ecosystems and those of the Late Jurassic, which were dominated by sauropods, concerns only the mass and height of the animals. None of the modern herbivores, including elephants and giraffes, reach a height comparable to that of most large sauropods, and no modern land animal requires such enormous amounts of food as these giants.

The other end of the scale

Some sauropods that lived in the Jurassic period reached fantastic sizes, for example, the brachiosaurus-like Supersaurus, whose remains were found in the USA (Colorado), probably weighed about 130 tons, i.e., it was many times larger than a large male African elephant. But these supergiants shared land with tiny creatures hiding underground that did not belong to dinosaurs or even reptiles. The Jurassic period was a time of existence of numerous ancient mammals. These small, furred, viviparous, milk-feeding warm-blooded animals were called multitubercular because of the unusual structure of their molars: numerous cylindrical “tubercles” fused together to form uneven surfaces, perfectly adapted to grinding plant food.

Polytubercles were the largest and most diverse group of mammals of the Jurassic and Cretaceous periods. They are the only omnivorous mammals Mesozoic era(the rest were specialized insectivores or carnivores). They are known from Late Jurassic deposits, but recent finds show that they are close to a little-known group of extremely ancient mammals of the Late Triassic, the so-called. Haramides.

The structure of the skull and teeth was very similar to today's rodents; they had two pairs of protruding incisors, giving them the appearance of a typical rodent. Behind the incisors there was a gap that did not contain teeth, followed by molars to the very end of the small jaws. However, the multitubercular teeth closest to the incisors had an unusual structure. In fact, these were the first false-rooted (premolar) teeth with curved sawtooth edges.

This unusual dental structure has reappeared in the process of evolution in some of the modern marsupials, for example, in the rat kangaroos of Australia, whose teeth are of the same shape and located in the same place in the jaw as the false-rooted teeth of polytubercles. When chewing food at the moment of closing the jaws, multituberculates could move the lower jaw back, moving these sharp saw-toothed teeth across the food fibers, and the long incisors could be used to pierce dense plants or the hard exoskeletons of insects.

A saurian megalosaurus (Megalosaurus) and its young that overtook an ornithischian scelidosaurus (Scelidosaurus). Scelidosaurus is an ancient species of dinosaur of the Jurassic period with unevenly developed limbs, reaching 4 m in length. Its dorsal shell helped protect itself from predators.

The combination of sharp front incisors, serrated blades and chewing teeth means that the feeding apparatus of multitubercles was quite versatile. Today's rodents are also a very successful group of animals, thriving in a wide variety of ecological systems and habitats. Most likely, it was the highly developed dental apparatus, which allows them to eat a variety of foods, that became the reason for the evolutionary success of multitubercles. Their fossilized remains, found on most continents, belong to different species: some of them apparently lived in trees, while others, reminiscent of modern gerbils, were probably adapted to exist in arid desert climates.

Changing Ecosystems

The existence of polytubercles spans a period of 215 million years, extending from the Late Triassic through the entire Mesozoic era to the Oligocene epoch of the Cenozoic era. This phenomenal success, unique among mammals and most terrestrial tetrapods, makes polytubercles the most successful group of mammals.

Small animal ecosystems of the Jurassic period also included small lizards of a wide variety of species and even their aquatic forms.

Thrinadoxon (cynodont species). Its limbs protruded slightly to the sides, and were not located under the body, as in modern mammals.

They and the rarely encountered reptiles of the group of synapsids (“beast-like reptiles”), tritylodonts, who survived to this time, lived at the same time and in the same ecosystems as polytubercular mammals. Tritylodonts were numerous and widespread throughout the Triassic period, but, like other cynodonts, suffered greatly during the Late Triassic extinction event. They are the only group of cynodonts to survive into the Jurassic period. By appearance they, like multitubercular mammals, closely resembled modern rodents. That is, a significant part of the ecosystems of small animals of the Jurassic period consisted of animals resembling rodents: trilodonts and polytubercular mammals.

Polytuberculates were by far the most numerous and diverse group of mammals of the Jurassic period, but other groups of mammals existed at this time, including: morganacodonts ( oldest mammals), amphilestids, peramurids, amphitherids, tinodontids and docodonts. All these small mammals looked like mice or shrews. Docodonts, for example, developed distinctive, wide molars well suited for chewing hard seeds and nuts.

At the end of the Jurassic period, significant changes occurred at the other end of the size scale in the group of large bipedal predatory dinosaurs, theropods, represented at this time by allosaurs (AUosaurus - “strange lizards”). At the end of the Jurassic period, a group of theropods emerged, called spinosaurids (“spiny or spiny lizards”), whose distinctive feature was a crest of long processes of the trunk vertebrae, which, perhaps, like the dorsal sail of some pelycosaurs, helped them regulate body temperature. Spinosaurids such as Siamosaurus (“lizard from Siam”), which reached a length of 12 m, along with other theropods shared the niche of the largest predators in the ecosystems of that time.

Spinosaurids had non-serrated teeth and elongated, less massive skulls compared to other theropods of this time. These structural features indicate that they differed in their feeding method from such theropods as allosaurs, Eustreptospondylus (“strongly curved vertebrae”) and ceratosaurs (Ceratosaurus - “horned lizard”), and most likely hunted other prey.

Bird-like dinosaurs

In Late Jurassic time, other types of theropods arose, very different from such huge, weighing up to 4 tons, predators as allosaurus. These were ornithominids - long-legged, long-necked, small-headed, toothless omnivores, strikingly reminiscent of modern ostriches, which is why they got their name “bird imitators”.

The earliest ornithominid, Elaphrosaums ("light lizard"), from the Late Jurassic deposits of North America had light, hollow bones and a toothless beak, and its limbs, both hind and forelimbs, were shorter than those of later Cretaceous ornithominids, and, accordingly, it was a slower animal.

Another ecologically important group of dinosaurs that arose in the Late Jurassic are the nodosaurs, four-legged dinosaurs with massive, shell-covered bodies, short, relatively thin limbs, a narrow head with an elongated snout (but with massive jaws), small leaf-shaped teeth, and a horny beak. Their name (“knobby lizards”) is associated with the bony plates covering the skin, protruding processes of the vertebrae and growths scattered across the skin, which served as protection from attacks by predators. Nodosaurs became widespread only in the Cretaceous period, and in the Late Jurassic they, along with huge tree-eating sauropods, were only one of the elements of a community of herbivorous dinosaurs that served as prey for a number of huge predators. 

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

general information

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

Main groups of sediments

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

The oldest stage

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

Early stage

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

Ancient stage

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

Middle stage

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

New stage

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

What is a geological period?

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

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

Triassic

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

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

Yura

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

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

Neogene

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

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

Geology as a science

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

"Frosty patterns on glass"

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

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

Was there a worldwide glaciation?

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

Mysticism, or Why Scientists Don't Notice the Obvious

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

Is geology an exact science?

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

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

Life in the seas.

As Pangea began to break apart, new seas and straits emerged, in which new types of animals and algae found refuge. Gradually on seabed fresh sediments accumulated. 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 ones formed there Coral reefs, sheltering numerous ammonites and new varieties of belemnites (old relatives of today's octopuses and squids).
On land, in lakes and rivers, there lived many different species of crocodiles, widely distributed throughout the globe. There were also saltwater crocodiles with long snouts and sharp teeth for catching fish. Some of their varieties even grew flippers instead of legs to make swimming more convenient. Tail fins allowed them to develop in water higher speed than on land. New species have also appeared sea ​​turtles. Evolution also gave rise to many species of plesiosaurs and ichthyosaurs, competing with new, fast-moving sharks and extremely agile bony fish.

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

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

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

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

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

Born for Speed

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

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

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

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

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

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

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

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

Age of dinosaurs.

The very first dinosaurs appeared more than 200 million years ago. Over the 140 million years of their existence, they have evolved into many different species. Dinosaurs spread across all continents and adapted to life in 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 largest family of large carnivorous dinosaurs were the megalosaurids, or "huge lizards." The megalosaurid was a monster weighing a ton, with huge, sharp saw-like teeth with which it tore the flesh of its victims. Judging by some of the fossilized footprints, his toes were turned inward. It may have waddled around like a giant duck, swinging its tail from side to side. Megalosaurids 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 powerful claws. Muscular forelimbs helped in hunting large plant-eating dinosaurs. The sharp claws undoubtedly left terrible lacerations in the side of the surprised victim. The powerful muscular neck of the predator allowed him to terrible force plunge dagger-shaped fangs deep into the body of the prey and tear out huge pieces of still warm meat.

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

Jurassic geological period, Yura, Jurassic system, middle period Mesozoic. Began 200-199 million years ago. n. and ended 144 million liters. n.

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

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

Climate and vegetation of the Jurassic period

Volcanic activity The end of the Triassic - the beginning of the Jurassic period caused transgression of the sea. The continents separated and the climate in the Jurassic period became more humid than in the Triassic. In place of the deserts of the Triassic period, lush vegetation grew in the Jurassic period. Huge areas were covered with lush vegetation. Jurassic forests consisted primarily of ferns and gymnosperms.

Warm and humid climate The Jurassic period contributed to the vigorous development of the planet's flora.

Ferns, conifers and cycads formed vast swampy forests. Araucarias, thujas, and cycads grew on the coast. Ferns and horsetails formed extensive forested areas. At the beginning of the Jurassic period, about 195 million years ago. n. Throughout the northern hemisphere, the vegetation was quite monotonous. 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.

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

The Jurassic period is the time of habitation of many famous dinosaurs. Of the lizards, these are Allosaurus and Diplodocus. Of the ornithischians, this is the stegosaurus.

During the Jurassic period, winged lizards - pterosaurs - reigned supreme in the air. They appeared in the Triassic, but their heyday was precisely in the Jurassic period. Pterosaurs were represented by two groups: pterodactyls and rhamphorhynchus.

During the Jurassic period, the first birds or something between birds and lizards appeared. Creatures that appeared in the Jurassic period and have the properties of lizards and modern birds called Archeopteryx. The first birds were Archeopteryx, the size of a pigeon. Archeopteryx lived in forests. They ate mainly insects and seeds.

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. Other important events took place in the warm and shallow seas of the Jurassic period.

The Jurassic period gave rise to many species of plesiosaurs and ichthyosaurs, competing with fast-moving sharks and extremely agile bony fish. and in sea ​​depths Leopleuradon patrolled its territory non-stop in search of food.

But one creature could rightfully be called the master Jurassic seas. This is a giant Liopleurodon weighing up to 25 tons. Liopleurodon was the most dangerous predator of the Jurassic seas, and perhaps in the entire history of the planet.

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

Jurassic tectonics:

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

This is what the Earth looked like at the end of the Triassic - the beginning Jurassic period
about 205 - 200 million years ago

This is what the Earth looked like at the end of the Jurassic period around 152 million years ago.

Jurassic climate and vegetation:

Volcanic activity of the end of the Triassic - the beginning Jurassic period caused sea transgression. The continents were divided and the climate in Jurassic period became wetter than in the Triassic. On the site of deserts of the Triassic period, in Jurassic period lush vegetation grew. Huge areas were covered with lush vegetation. Forests Jurassic period consisted mainly of ferns and gymnosperms.
Warm and humid climate Jurassic period contributed to the vigorous development of the planet's flora. Ferns, conifers and cycads formed vast swampy forests. Araucarias, thujas, and cycads grew on the coast. Ferns and horsetails formed vast forest areas. At first Jurassic period, about 195 million years ago Throughout the northern hemisphere, the vegetation was quite monotonous. But already starting from the middle of the Jurassic period, about 170-165 million years ago, two (conditional) plant belts were formed: northern and southern. The northern plant belt was dominated by ginkgo and herbaceous ferns. IN 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 Jurassic period and are still preserved in some parts of the wild today. Horsetails and mosses were almost no different from modern ones. Places where ferns and cordaites grow Jurassic period now occupied by tropical forests, consisting mainly of cycads. Cycads are a class of gymnosperms that predominated in the green cover of the Earth Jurassic period. 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 Jurassic period Ginkgos are also common - deciduous (which is unusual for gymnosperms) trees with an oak-like crown and small fan-shaped leaves. Only one species has survived to this day - Ginkgo biloba. The first cypress and, possibly, spruce trees appear precisely during the brisk period. Coniferous forests Jurassic period were similar to modern ones.

Land animals Jurassic period:

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

One of the fossil creatures Jurassic period, combining the characteristics of birds and reptiles, is Archeopteryx, or 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).

Kings of the Jurassic Sky:

IN Jurassic period Winged lizards - pterosaurs - reigned supreme in the air. They appeared in the Triassic, but their heyday was precisely Jurassic period Pterosaurs were represented by two groups pterodactyls 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 or carrion, sometimes sea lilies, mollusks, and insects. In order to fly, pterodactyls were forced to jump from cliffs or trees.

IN Jurassic period the first birds or something in between birds and lizards appear. Creatures that appeared in Jurassic period and having the properties of lizards and modern birds are called Archeopteryx. The first birds were Archeopteryx, the size of a pigeon. Archeopteryx lived in forests. They ate mainly insects and seeds.

But Jurassic period is not limited to just animals. Thanks to climate change and rapid development of flora Jurassic period, the evolution of insects accelerated dramatically, and as a result, the Jurassic landscape was eventually filled with the endless buzzing and crackling sounds of many new species of insects crawling and flying everywhere. Among them were the predecessors of modern ants, bees, earwigs, flies and wasps.

Masters of the Jurassic Seas:

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

Compared to the Triassic, in Jurassic period The population of the seabed has changed greatly. Bivalves displace brachiopods from shallow waters. Brachiopod shells are replaced by oysters. Bivalve mollusks fill all life niches of the seabed. Many stop collecting food from the ground and switch to pumping water using their gills. In warm and shallow seas Jurassic period Other important events also took place. IN Jurassic period folds up new type reef communities, approximately the same as what exists now. It is based on six-rayed corals that appeared in the Triassic. The resulting giant coral reefs sheltered numerous ammonites and new species of belemnites (old relatives of today's octopuses and squids). They also housed many invertebrates, such as sponges and bryozoans (sea mats). Gradually, fresh sediment accumulated on the seabed.

On land, in lakes and rivers Jurassic period There were many different species of crocodiles that spread widely across the globe. There were also saltwater crocodiles with long snouts and sharp teeth for catching fish. Some of their varieties even grew flippers instead of legs to make swimming more convenient. The tail fins allowed them to develop greater speed in the water than on land. New species of sea turtles have also appeared.

All dinosaurs of the Jurassic period

Herbivorous dinosaurs: