Elasmosaurs are ancient sea lizards. Volga sea lizards Ancient sea lizards

The Paleozoic era was followed by one of the most remarkable periods in the history of life on Earth - the reign of the Mesozoic reptiles. Within the Mesozoic, over a period of 190 million years, an astounding spread of reptiles took place. The reptiles that evolved during the Late Carboniferous, thanks to the advantages of reproduction using the amniotic egg, spread on land, populated the seas and took to the air using newly developed wings. One branch of the reptiles gave rise to birds that competed with the flying reptiles themselves. The other branch, as we have already seen, developed into the mammalian branch. And yet the most striking characters in the drama of reptiles are dinosaurs. They and all their relatives, swimming and flying, died out in the Mesozoic era. They died out completely, to the last individual, leaving the Earth to populate the Earth with new groups of animals, mainly descendants of Mesozoic mammals.

The fossil record testifies to the existence of hundreds of genera of dinosaurs ranging in size from a chicken to tens of meters, which had dozens of the most diverse adaptations to life in various conditions. And yet, like all other reptiles, all dinosaurs were probably cold-blooded and directly or indirectly dependent on the presence of a large amount of deciduous vegetation. However, dinosaur fossils have been found on every continent except Antarctica. From this circumstance, we can conclude that during the Mesozoic time, lowlands with a mild climate and lush vegetation were widespread, since animals like dinosaurs could not exist in high mountains with steep slopes and in a cold climate. This conclusion seems to agree with the data we have on the movements of the earth's crustal plates. Looking again at Figure 27, we can see that most of the land area that is now located in the middle or high latitudes was (presumably) at lower latitudes in the middle Mesozoic. It is possible that the southern part of North America and the southern part of Europe then adjoined the equator. If the continents had occupied the same position in the Mesozoic as they do now, then it is unlikely that reptiles would have been so numerous and reached such enormous sizes.

Using the map shown in Figure 38, we can explain the rise of the Mesozoic reptiles from a different perspective. By the end of the Mesozoic, the territory of North America, compared to the present time, was more occupied by shallow seas and to a lesser extent by land, mostly low-lying, and the Gulf of Mexico was connected to the Arctic Ocean. Under these conditions, the climate of the central and northern parts of the continent may have been milder than now, especially in winter. Both in Europe and on other continents, extensive seas were common in the Mesozoic.

Thus the flowering of reptiles in the Mesozoic era, which at first sight seems inexplicable, is finally satisfactorily explained by the presence of environmental conditions that were favorable for cold-blooded animals. Thus, as in the case of earlier stages in the history of living beings, we are once again convinced that environmental conditions have a decisive influence on the development of the animal world through natural selection.

Dinosaur types

We have already said that there were several hundred species of dinosaurs. But they all belonged to two distinct divisions that descended from a common ancestor in the Triassic, before dinosaurs as such appeared. The name "dinosaur" is more popular than scientific. It means "terrible lizard" and when it was first introduced, it referred to very large and ferocious animals. But dinosaurs of this type were relatively few among the many reptiles that we currently classify as dinosaurs. This group includes a large number of reptiles that did not possess either ferocity or large size.

Mentioned the main two divisions of dinosaurs, scientists distinguish on the basis of the structure of their pelvic bones. One included dinosaurs, in which the pelvic bones had the same structure as those of lizards, and the second included dinosaurs, whose pelvic bones resembled those of birds. This important structural difference in the device is shown in Figure 46. There is no need to dwell on this in more detail, we are primarily interested in the appearance and lifestyle of dinosaurs. Therefore, we can move on to describing some of the most prominent representatives of the world of dinosaurs. The Triassic dinosaurs were quite primitive and modest in size. All of them leaned on their hind legs, and the front ones, which were much smaller in size, did not reach the ground (Fig. 47). Their necks were much longer than those of the Permian crawling reptiles. However, although the dinosaurs became bipedal, they were not upright like a bipedal man. When they walked or ran, their body took a position closer to the horizontal than to the vertical, although, no doubt, they could sometimes straighten up, as squirrels often do. As for the legs of dinosaurs, looking at the footprints left by them on wet sand and silt (photo 18), on which the prints of three or four long fingers and another short, additional, only occasionally touching the ground, are clearly visible, we can understand why the first the researchers of these traces took them for traces of birds.

Rice. 46. ​​Connection between groups of dinosaurs mentioned in the book

Most dinosaurs were predators, like their Permian ancestors; the presence among the Triassic fossils of varieties with unusual armor, outgrowths and spikes suggests that they were already beginning to "take" defensive measures against their enemies - other predatory dinosaurs.

Rice. 47. Coelophysis, a typical Triassic dinosaur. It is very likely that the small footprints shown in photo 17 were left by this particular dinosaur.

Naturally, this group of rather primitive Triassic dinosaurs included the ancestors of all later dinosaurs. It is best to subdivide them according to the method of nutrition, lifestyle and structural features. We can distinguish between herbivorous and carnivorous, bipedal and quadrupedal dinosaurs, as well as dinosaurs that had armor, bone plates or protective horns, and those who did not have these adaptations. We will divide the lizards we are considering into four large groups.

Herbivorous bipeds. Although almost all early Mesozoic dinosaurs were predators, there were many herbivorous individuals among their descendants. Judging by the tracks they left, they quite often moved on four legs. Among them, Iguanodon was common (Fig. 48), an animal of dense build, reaching about 11 meters in length. In one place, more than 20 skeletons were found in complete safety, according to the skeletons of turtles, crocodiles and fish found together with them, one can think that these dinosaurs lived in swamps. Their "hands" had five fingers, and the "thumb" was a large sharp spike, probably serving as a good defense tool. Obviously, these lizards fed by bending the branches of trees with their forelimbs and eating around the shoots. Their footprints show that they moved at a walk and probably not very fast, only occasionally making short jumps.

Rice. 48. Iguanodon, a large bipedal herbivorous dinosaur that lived in Europe

Another group of herbivorous bipedal lizards, reaching 6-12 meters in length and called hadrosaurs, resembled amphibians in their way of life and lived in swamps or on their swampy shores (photo 43). Between the toes they had small membranes, and the tail was thin, like those of crocodiles, and when moving in the water it acted like an oar. The nostrils were positioned so that almost the entire body could be submerged in water. The mouth consisted of a horny beak, similar to a duck. There were up to a thousand teeth on the jaw, long, very thin, located close to each other. When the horny beak took soft plants out of the swamp, the upper and lower jaws, on which teeth grew, began to move back and forth and rub against each other, like two wire brushes, thus grinding the food.

Photo 43. Hadrosaurs (1), an "armored" ankylosaurus-like dinosaur (2) and carnivorous dinosaur Struthiomimus (3). The tree on the left is an angiosperm. Reconstruction

carnivorous bipeds. Where there are herbivorous animals, there are always predators that prey on them. Among the dinosaurs there were many predators running on two legs of various sizes and shapes. One of them, Ornitholestes, was only about two meters long and was so "graceful" in structure that it supposedly weighed less than 25 kilograms. It was an agile animal adapted to a fast run; grasping forelimbs with three very long fingers could catch even a very small lizard that tried to escape. Another dinosaur, Struthiomimus (3rd number, photo 43), was slightly larger and resembled an ostrich. He even had a toothless beak. The shattered skull of a related dinosaur was found in a fossil nest containing dinosaur eggs. This circumstance, as well as the general appearance of the animal, which had a small weight and flexible "arms", leads us to the conclusion that Struthiomimus fed on eggs and robbed nests.

Another dinosaur, Deinonychus, about 2.5 meters long, which may have been a descendant of the dinosaur Ornitholestes, was distinguished by two very interesting adaptations that allowed it to lead a predatory lifestyle. The second toe on each hind foot was provided with a claw much longer and sharper than all the other claws. This finger had a special joint that allowed it to rise above the ground and turn 180° (Fig. 49), which allowed the reptile to inflict a strong kick on its prey, a kick that could rip open the belly of an animal of the same size as the predator itself. In addition, the long tail of this dinosaur contained tendons that could instantly "splice" the bones together, turning the tail into a rigid counterbalance to the entire body. Possessing similar claws and tail, such a dinosaur; must have been a very mobile and dangerous animal.

Rice. 49. Deinonychus, a predator armed with sharp claws

Some bipedal predators were much larger, exceeding 9 meters in length. One of them, Tyrannosaurus Rex, was the largest known land carnivore; it had a length of up to 15 meters, a height of up to 6 meters and presumably weighed 7-8 tons (photo 44). The length of his skull was 1-2 meters, and in his mouth were many sharp serrated teeth fifteen centimeters long. Since its forelimbs were very short, it apparently did not use them when it attacked and ate prey. The main prey of Tyrannosaurus were herbivorous dinosaurs, such as hadrosaurs and dinosaurs armed with horns.

Photo 44. Tyrannosaurus, the largest predator, attacks a Triceratops, which has prepared for defense. The head of a Triceratops is covered with an armored helmet. The trees are angiosperm palms. Reconstruction

Amphibious quadrupeds. Let's move on to giant dinosaurs, which are so often described in popular literature that their appearance is familiar not only to scientists. The fossil record contains evidence of at least four different genera, superficially very similar; we will mention only two of them. At first glance, it may seem strange that, although the dinosaurs of these two genera were quadrupedal, their front legs were much shorter than their hind legs. But in reality, this was to be expected, because they were descendants of Triassic bipedal dinosaurs with short forelimbs. Perhaps the best known is the genus Apatosaurus (photo 45) - huge, inactive herbivores, reaching 23 meters in length; their short torso was supported by massive columnar legs equipped with claws. In front was a long flexible neck with a small head, which was balanced in the back of the body by a long flexible tail, tapering towards the end. The animal had to weigh more than 30 tons, that is, four or five times more than the largest African elephant.

Photo 45. Apatosaurus, a four-legged amphibian-like dinosaur, more than 20 m long, on the shore of a Jurassic reservoir. Two other similar dinosaurs graze in the water. Compared to them, the crocodile in the foreground looks very small. The vegetation consists of cycads and horsetails. Reconstruction

As the size and weight of the ancestors of this dinosaur increased, the evolution of the skeleton took place in the direction of reducing its weight through the formation of cavities and holes in the vertebrae; thus, the weight was reduced where the loads were small, and maintained where strength was important, for example, in columnar legs. The footprint of this dinosaur, left in the Mesozoic mud, exceeds 90 centimeters in length.

Another giant dinosaur, the diplodocus, was also a herbivore, similar in many ways to the one described above. The main difference from it was that the diplodocus was somewhat longer (the length of one specimen, according to calculations, exceeded 29 meters with a height of almost 14 meters), but not so massive, its weight was supposedly 10-12 tons. Without a doubt, these giants spent most of their time in swamps and rivers, eating soft plants. Away from the coast, among the swampy islands, they were safer from large predators; therefore, such places were for them not only a "dining room", but also a refuge. For even greater security, the nostrils of these giants were placed on the very top of the head, which allowed them to breathe calmly, almost completely submerged in water and thus out of sight of enemies. These and some other dinosaurs swallowed their plant food whole and ground it up after it got into their stomachs. Like chickens, which usually have a lot of stones in their crops, dinosaurs swallowed stones the size of a potato and, with the help of these tools, crushed food with their strong stomach muscles. Sometimes heaps of such stones, once rounded and polished in the stomachs of dinosaurs, are found along with their skeletons, and they are located where the belly of a large dinosaur was located.

Probably, these huge animals laid eggs, although this has not yet been confirmed by finds; eggs died in the water, so they had to lay them on land, and maybe on islands or in other places where it was difficult for predators to penetrate.

Huge, four-legged amphibian-like dinosaurs had an even smaller brain relative to body weight than other dinosaurs, although this group was not very famous for its mental abilities. In Diplodocus, the true brain weighed only about seven grams per ton of body weight. We say "true brain" because diplodocus, like many other dinosaurs, had a much larger additional coordinating center located in the spine, near the pelvis. This center connected with the true brain through the dorsal and controlled the movement of the hind legs and tail. Although such a device may seem inconvenient, we must admit that it worked "perfectly" because it was possessed by many different types of dinosaurs that lived for tens of millions of years. This, of course, was facilitated by the habitat of dinosaurs with a mild climate and little changing natural conditions; in such an environment, there were almost no problems requiring mental effort.

Quadrupeds equipped with armor or horns. Our list of diverse dinosaurs also includes a rather heterogeneous group of species that, while not closely related, possessed unusual armor, or horns, or both. Although their Triassic ancestors were bipedal, these dinosaurs once again descended to all four limbs. Yet their front legs were still shorter than their hind legs, like those of Apatosaurus. Being herbivores, they needed protection from predatory reptiles; this caused the development of armor and protective horns.

The most prominent of these armored reptiles was the Stegosaurus. On its skeleton, which is about 6 meters long and presumably weighs 4 tons, thick triangular bone plates are visible, bordering the spinal column, to which they were probably connected by ligaments. Perhaps these plates, the largest of which reached a size of 75 centimeters, protected the spine from bipedal predators, which, probably, when attacked, tried to cling to the scruff of the neck, as a terrier does when killing a rat. In addition, the stegosaurus was armed with a pair of strong thick spikes about 60 centimeters long, located at the end of the tail. One blow of such a tail could probably knock down a fairly large opponent and also cause serious damage to him.

Ankylosaurus and its relatives (photo 43) probably had such protection as modern armadillos have. Reaching 6 meters in length and 2.5 meters in width, they had a height of less than 1.5 meters. Behind a powerful, thick, beaked skull, the entire upper half of their body was covered with heavy bony plates. Some of them also had huge spikes along their entire body, from the shoulders to the tail, which resembled a heavy spatula or club. With such protective armor, these reptiles probably moved slowly. But when danger approached, they could cling to the ground, tucking their paws under themselves, and defend themselves from an attack by striking with their tail.

In another way, using horns, Triceratops and its numerous relatives defended themselves (photo 44). These bulky short-tailed quadrupeds reached 7.5 meters in length and three meters in height. Their most characteristic feature was a huge, heavy skull that extended back like a large shield protecting the neck. In front, the skull was equipped with two horns, protruding above a narrow beak, similar to the beak of a parrot. Inside the skull was a brain, small in our opinion, but large enough for a dinosaur. The presence of such a brain suggests that these animals, which had a protective helmet and horns, were quite mobile. This is evidenced by the insecurity of the back of their body, which had neither armor nor any weapons. It is clear that they could turn quickly to repel the enemy attack with their horns. The traces of such ancient battles are probably the scars often found on the fossil remains of the neck armor.

When we talk about fights between dinosaurs, we can't help but wonder if they took place in silence or were accompanied by loud screams, as happens in the fights of modern cats and dogs. Dinosaur anatomy experts can tell us what little is known on this subject. It appears that the configuration of the small ossicles at the base of the tongue in dinosaurs is similar to that of the same ossicles in some living animal species. Based on this analogy, it is possible that at least some dinosaurs could make croaking or barking sounds, as modern crocodiles do. Therefore, if in the Paleozoic, silence most likely reigned on land, broken only by the noise of the wind, streams and surf, then the Mesozoic landscapes could already be enlivened by the sounds that animals made.

Protoceratops, related to Triceratops, but less complexly organized small dinosaur, with a beak but without horns, lived in Asia, became widely known in connection with the discovery of its eggs and nests by a paleontological expedition in Mongolia in the twenties of our century. In the late Mesozoic, this area was as dry as it is now, and the eggs were laid in small depressions in the sand, which has now become sandstone. Dinosaur females dug holes and laid up to 15 eggs 15-20 centimeters long in them. Several such nests have been found, and at least two of the eggs contained tiny bones of baby dinosaurs that failed to hatch. Eggs of other types of dinosaurs, both larger and smaller, have also been found.

marine reptiles

When studying life in the Mesozoic, perhaps the most striking thing is that almost half of all known reptile species lived not on land, but in water, in rivers, estuaries, and even in the sea. We have already noted that in the Mesozoic, shallow seas were widespread on the continents, so there was no shortage of living space for aquatic animals.

In the Mesozoic layers, there are a large number of fossil reptiles adapted to life in the water. This fact can only mean that some reptiles returned back to the sea, to their homeland, where once upon a time the ancestors of dinosaurs appeared - fish. This fact requires some explanation, since at first glance there was a regression here. But we cannot consider the return of reptiles to the sea as a step back from an evolutionary point of view only on the grounds that the Devonian fishes emerged from the sea onto land and developed into reptiles, passing through the amphibian stage. On the contrary, this proposition illustrates the principle that each actively developing group of organisms tends to occupy all the varieties of environment in which it can exist. In fact, the movement of reptiles into the sea is not too different from the colonization of rivers and lakes by amphibians in the Late Carboniferous (photo 38). There was food in the water and the competition was not too fierce, so first amphibians and then reptiles moved into the water. Already before the end of the Paleozoic, some reptiles became aquatic inhabitants and began to adapt to a new way of life. This adaptation went mainly along the path of improving the way of movement in the aquatic environment. Of course, the reptiles continued to breathe air in the same way as the modern whale breathes air, a mammal, although similar in body shape to a fish. Moreover, the Mesozoic marine reptiles did not evolve from any one land reptile that made the decision to go back into the water. Fossil skeletons provide undeniable evidence that they had different ancestors and appeared at different times. Thus, fossil remains show how varied the response of organisms to changing environmental conditions was, as a result of which a vast expanse abounding in food and suitable for settlement was created.

Extensive information has been obtained from the study of fossils contained in marine mudstones and Cretaceous limestones; in these fine clastic rocks, not only bones are preserved, but also imprints of skin and scales. With the exception of the smallest and most primitive species, most marine reptiles were carnivores and belonged to three main groups: ichthyosaurs, plesiosaurs, and mosasaurs. Briefly characterizing them, we must first of all note that ichthyosaurs acquired an elongated shape similar to fish (Fig. 50) and were excellently adapted for fast swimming in pursuit of fish or cephalopods. These animals, reaching 9 meters in length, had bare skin, a dorsal fin and tail like a fish, and their four limbs turned into a kind of seal flippers and were used to control the movement of the body when swimming. All fingers in these flippers were closely connected, and additional bones existed in them to increase strength. The large eyes of ichthyosaurs were adapted to see well in the water. They even had one very significant improvement in the process of reproduction. Being animals that breathed air but lived in sea water, they could not lay eggs. Therefore, ichthyosaurs developed a method of reproduction in which the embryo developed inside the mother's body and, reaching maturity, was born alive. They became viviparous. This fact is established by the finds of excellently preserved remains of female ichthyosaurs with fully formed cubs inside their bodies, the number of cubs reaches seven.

Rice. 50. Four groups of animals that acquired a streamlined body shape as a result of adaptation to life in water: A. reptile, B. fish, C. bird, D. mammal. Initially, they had a different appearance, but in the course of evolution they acquired an external resemblance.

The second group includes plesiosaurs, which, unlike fish-like ichthyosaurs, retained the original shape of the reptile body, reaching 7.5-12 meters in length. If not for the tail, the plesiosaur would have looked like a giant swan. Of course, the ancestor of the plesiosaur was not at all the terrestrial reptile that gave rise to the ichthyosaurs. The legs of the plesiosaurs turned into long fins, and the head, planted on a long neck, was equipped with sharp teeth that closed and securely held the most slippery fish. Such teeth excluded chewing; The plesiosaurus swallowed the prey whole and then crushed it in the stomach with the help of pebbles. The diet of plesiosaurs can be judged from the stomach contents of one of them, which, apparently, died before the stones in his stomach had time to grind the food he swallowed to the right extent. The bones and fragments of shells contained in the stomach were found to belong to fish, flying reptiles and cephalopods, which were swallowed whole, along with the shell.

A third group of marine reptiles are called mosasaurs because they were first discovered near the Moselle River in northeastern France. They could be called "late" because they appeared in the late Cretaceous time, when ichthyosaurs had inhabited the seas for almost 150 million years. The ancestors of mosasaurs were lizards rather than dinosaurs. Their length reached 9 meters, they had scaly skin, and their jaws were arranged in such a way that they could open their mouths wide, like snakes.

A streamlined body as an adaptation to the conditions of life in the aquatic environment is found not only in ichthyosaurs and mosasaurs. The same can be seen in a number of animals that lived both before and after the Mesozoic, and in the Mesozoic (Fig. 50).

reptiles in the air

The history of the heyday of reptiles in the Mesozoic does not end with the above. The reptiles not only spread on land and filled the seas, they also took to the air, following two lines of evolution at once. They learned to fly like reptiles, and besides, moving along a completely different path of development, they learned to fly like birds. As far as can be judged from fossil remains, true flying reptiles were not as numerous as marine ones. However, they were the first animals to take to the air after insects, which did so back in the Devonian time. Naturally, the air environment is more difficult to conquer and more dangerous than the sea. Moving through the air, or even passively hovering, requires more specialized gear, more energy, and more skill (by which we mean agility and quick reactions) than moving through water. This is basically why man built ships long before airplanes. The interval between these inventions of man was about several thousand years. And between the emergence of reptiles in the late Carboniferous time and their penetration into the air (Jurassic time), about 80 million years passed.

We know a lot about the structure and appearance of flying reptiles due to the fact that in the southern part of Germany [Germany, Bavaria. - Ed.] sedimentary rocks of an unusual type are widespread. These rocks are beds of late Jurassic limestone, so fine-grained that it was used to engrave illustrations for books (before steel and copper plates were used for this purpose), and for this it was called lithographic stone. The unusually fine-grained composition of these limestones suggests that they were deposited in shallow lagoons protected from the waves of the open sea by sand bars or coral reefs. Loose deposits at the bottom of the lagoons retained the imprints of even the smallest details of plants or animal bodies, which sank to the bottom and were covered with silt. As a result, lithographic stone is famous for its plant, invertebrate, fish, and reptile fossils.

Photo 46 Skeleton of Rhamphorhynchus, a primitive flying reptile, found in lithographic limestone in Germany

Many winged reptiles have been found in these deposits, in addition, similar remains have been found in other layers of the Mesozoic age in various places. Examining the remains of one of the Jurassic primitive reptiles, preserved to the smallest detail (photo 46), we see that its body has adapted to flight in the following ways: 1) weight has decreased; 2) there were "devices" for flight control; 3) a mechanism for flight was created. Here are some of these devices:

1. Small body size; while some flying reptiles were the size of a turkey, others were no larger than canaries. The skeleton was made lighter by the development of thin hollow wing bones, and in some species the skull was almost reticulated and consisted of thin bones.

2. Unusually, the eyes and the part of the brain that controls vision were well developed.

3. The most remarkable feature was the wings. Looking at figures 51 and 52, we can easily imagine that the fourth finger on the forelimb, the word "little finger", was unusually elongated in relation to the rest. From the tip of this finger to the hind leg and further to the tail, a thin membrane of skin was stretched, forming a wing.

Rice. 51. Pteranodon (Pteranodon), a flying reptile with an outgrowth on the skull; he flew vast distances over vast chalk seas in what is now the states of Kansas and Nebraska

All three groups of devices, taken together, created a device that, although clumsy, could fly. The formation of the wing, accompanied by an improvement in the eye and a reduction in overall weight, made flight possible and led to amazing body proportions. For example, one of the flying reptiles with a wingspan of 90 centimeters, according to calculations, weighed less than 450 grams in life. The skin of such reptiles was bare, and the jaws were equipped with numerous sharp teeth, common to reptiles. Probably, these animals, like modern buzzards, hovered more than they flew. Descended from terrestrial predators, they apparently remained carnivorous and, slowly gliding over the water, looked out for marine animals or large insects. The structure of their skeleton shows that they could not walk. Obviously, they did not land on the surface of the earth, but on the branches of trees or ledges of rocks on which they hung, like modern bats.

Rice. 52. Scheme of comparison of the wing of a flying reptile, a bat and a bird. All these wings appeared at different times. In a reptile, the entire wing is supported by only one finger. In a bat, the outer part of the wing is reinforced with four fingers. In a bird, most of the wing is supported by the bones of the shoulder and forearm, and the bearing surface is formed by light, stiff feathers. Of all three types, such a wing is most suitable for its purpose.

Later, the development of flying reptiles, the remains of which were found in the sediments of the shallow seas of the Cretaceous, took the path of replacing teeth with a long beak, which, of course, better suited their lifestyle. In one of the genera, a special protrusion, or crest, appeared in the back of the skull (Fig. 51), which, perhaps, balanced the long beak and made it easier for the reptiles to maneuver in the wind. But the main change concerned the increase in the area of ​​​​the wings, apparently in order to better support the body in the air. One of the flying reptiles to support the body, which supposedly weighed less than 12 kilograms, had wings with a span of 7.5 meters. This wingspan allows these reptiles to be considered the largest flying animals in the entire history of life on Earth. Although the flying reptiles were fragile until the very end of their heyday, they still existed for more than 100 million years.

But despite the fact that the wing of reptiles performed its functions and existed for a long time, it was a less successful adaptation for flight than the wing of a bird that appeared independently of it and, later, of mammals - bats. Figure 52 shows all three wings, and, as can be seen, the bird's wing is the most perfect of them.

Birds

In the Jurassic, reptiles living along the shores of warm seas had various types of flight. We have already seen that several species of terrestrial reptiles have taken to the air using the leathery wings just described. But one species went even further. In one of the quarries during the development of lithographic stone in the middle of the 19th century. a fossil skeleton of a reptile was found, no larger than a crow, which had large eyes, teeth, like those of reptiles, and fingers with claws on its forelimbs. It is striking that very clear imprints of feathers attached to the forearm and to the vertebrae of the long tail were found. It was definitely a bird. It received the generic name Archeopteryx (Archaeopteiyx) ("ancient wing") and the species name Uthographica after the name of the rock (photo 47). Two more fossil skeletons and a single feather impression were found in the same layer.

Photo 47. Archeopteryx (Archaeopteryx), the oldest bird known to us, sits on a branch of a coniferous tree, about to eat a caught lizard. In the foreground on the right are cycad plants; behind - coniferous trees and another similar bird. Reconstruction

Of course, these finds were of extraordinary interest and therefore were carefully studied. The results of the research can obviously be summarized as follows: Archeopteryx in its main features is a flying reptile, but since, by definition, birds have feathers, and reptiles do not, it can be attributed to birds. The structural features of Archeopteryx allow us to confidently say that this oldest bird known to us descended from a bipedal reptile that lived on earth. The presence of feathers strongly suggests that she had warm blood, because one of the main functions of feathers is thermal insulation. Many birds have even warmer blood than humans. Their feather cover and high motor activity allow them to maintain a normal body temperature of about 39.5 ° C.

Feathers are made up of the same tough horny substance as scales. Some scientists suggest that the small reptile that was the ancestor of these primitive birds had scales, and that the scales first became wavy at the edges, perhaps because this shape prevented the skin from overheating from the sun's rays. The wavy edges proved useful in another way as they reduced the loss of heat from the body, and gradually these scales turned into feathers. The rigidity and light weight of the feathers made them ideal for flight.

Although the first bird had feathers, it, like its relatives - flying reptiles with leathery wings, did not fly well. Its structure indicates that the bird was probably well adapted for gliding flight. Perhaps she lived on land and, being a predator, fed on either small animals or carrion. The fact that its remains were found in marine limestones only indicates that individual specimens were blown into the sea by wind or current and buried in soft bottom silt. The fragile bodies of birds that died on land simply did not survive.

By the Cretaceous period, the clumsiness of flight in birds had disappeared, and many of them acquired beaks instead of teeth. Some birds have adapted to life on the water. An example is the very loon-like floating and diving bird Hesperornis (Fig. 50), which was about two meters long and which still possessed teeth and wings, although not as strong and smaller than those of flying birds. The existence of birds that almost left the air to swim suggests that early birds preyed on fish in the same way that reptiles have consistently done since the early Mesozoic era.

The End of the Huge Reptiles

The end of the Cretaceous period, which meant the end of the entire Mesozoic era, can be called a "crisis" in the history of the biosphere, because at that time many groups of animals became extinct. Reptiles suffered the most noticeable damage. All dinosaurs, all flying reptiles, and all marine reptiles died out, with the exception of sea turtles; only lizards, snakes and turtles survived and continued the line of reptiles. Of the invertebrates, most cephalopods have disappeared, including all belemnites, as well as some lines of marine bivalves and snails.

The extinction was selective because mammals and land plants were little or no affected, while fish and many invertebrates survived completely. Therefore, attempts to attribute this extinction to any one cause have been unsuccessful. Until the timing of major events in Earth's history was determined by radiometric dating, the end of the Mesozoic was commonly referred to as the time of the "great extinction". However, we now realize that this expression is not true. At least two circumstances indicate that the extinction did not have the character of a catastrophe that destroyed all life.

First, it was selective, affecting some species and sparing others. In addition, it was not limited to any one type of natural environment, covering land, sea and air. Second, although the most notable extinction was at the end of the Cretaceous, it took a considerable amount of time overall. In particular, various groups of reptiles died out at separate points in time throughout the Mesozoic. Therefore, whatever the cause of this phenomenon, it obviously did not cause the "sudden" extermination of species, at least in the sense of the word in which we apply it to the events of the history of human society. Even the most pronounced extinction, which occurred at the end of the Cretaceous period, probably lasted several million years.

Looking at the geologic record of what happened at the end of the Cretaceous, we see that the continents as a whole have become taller. At the same time, and perhaps mainly as a result of this uplift, the areas of the vast shallow seas on the continents were reduced and the marshy lowlands located along the shores of these seas disappeared. In addition, temperatures have dropped, partly due to the rise and shrinkage of the seas.

We must admit that the actual cause of extinction has not yet been established. The explanations previously put forward - disease, lack of food, and most vaguely - "loss of vitality" - are completely unable to explain why there was a selective disappearance of some of the inhabitants of the land, sea and air, and not the complete extinction of the inhabitants of any one environment. It appears that the mammals emerged from this catastrophe unharmed.

It has recently been suggested that the end of the Mesozoic was marked by a series of reversals of the earth's magnetic field (described in Chapter 6) and that these reversals may have affected the biosphere in some way, for example by changing the intensity of radiation reaching the earth's surface. There have been objections to this, but perhaps it is too early to evaluate all the pros and all the cons. Suffice it to say that the extinction that marked the end of the "age of dinosaurs" is still one of the greatest mysteries associated with the history of life on Earth.

Literature

Augusta Joseph, Burian Zdenek. 1961, Prehistoric reptiles and birds: Paul Hamlyn, London.

Colbert E. H., 1951, The dinosaur book: NcGraw-Hill Book Co., Inc., New York.

Colbert. E.H., 1961, Dinosaurs. Their discovery and their world: E. P. Dutton & Co.. Inc., New York.

Fenton C.L., Fenton M. A., 1958, The fossil book: Doubleday & Co.. New York, p. 329-374.

Kurten Bjorn, 1968, The age of the dinosaurs: Weidenfeld and Nicolson, London. (Paperback.)

Swinton W. E., 1958, Fossil birds: British Museum (Natural History), London.

Swinton W. E. 1970, The dinosaurs: Wiley-Interscience, New York.

Elasmosaurs are ancient lizards of the plesiosaur order. They reigned on the planet in the Triassic period, and in the Cretaceous period they were gone.

The average body length of Elasmosaurus was about 15 meters. The spine was formed from a large number of flat vertebrae, which could be up to 150 pieces.

The evolutionary process changed the limbs of elasmosaurs and turned them into large flippers.

These dinosaurs once lived in the sea, which was previously located on the site of modern Kansas.

Elasmosaurs were the most unusual creatures of the suborder. They had a very long and flexible neck, ending in a small head. At the same time, the Elasmosaurus had a wide mouth, and the teeth were shaped like spikes.

By the number of cervical vertebrae, these dinosaurs are certainly in first place among the rest. For example, we can compare the cervical region of a giraffe, which consists of only 7 vertebrae.

These lizards could catch the fastest fish, the long neck helped to grab agile prey.

At times, these dinosaurs went to shallow water, lay down on the bottom and swallowed small pebbles, which helped to crush food and acted as ballast. About 250 stones were found in the stomach of one lizard. After examining the stones, scientists realized that elasmosaurs traveled several thousand kilometers throughout their lives, and collected stones in different parts of the coast. Most likely, the offspring of elasmosaurs, like other ichthyosaurs, were born in the sea.

For the first time, the remains of this creature were found in 1868 by E. Kop. Elasmosaur bones have been found in the United States, Japan, and Russia. These dinosaurs got their name from the flat bones of the pelvic and shoulder girdle.

The land of the Volga region keeps the remains of giants who plied the sea during the time of the dinosaurs.

In the early August morning of 1927, on the outskirts of Penza, not far from the ancient Mironositsky cemetery, a man appeared with a duffel bag over his shoulders - a political exile of the new time Mikhail Vedenyapin. He went down to the Prolom ravine, to a small machine-gun shooting range. There were no exercises that day, and in the ravine one could meet only boys who ran to collect cartridge cases.

Mikhail Vedenyapin had been living in Penza for two years, in exile. Before that, he was exiled by the tsarist courts, Admiral Kolchak promised to shoot him, and now the Bolsheviks did not like his views. And now the former professional revolutionary SR works as a statistician, at his leisure he writes notes in the journal Hard Labor and Exile and wanders around the neighborhood in search of fossils. He, like many scientists and just curious of those times, has ten years left to live ...

He walked along the slope of a deep ravine, picking up from the ground the shells of mollusks that lived in a long time ago - more than 80 million years ago - the disappeared sea. In one place, the sandy slope was broken by machine-gun fire, and fragments of bones lay in the scree. The local historian collected them and climbed onto the cliff to see where it all fell out from. It didn't take long to search: huge bones stuck out of the sand.

Vedenyapin immediately went to the local history museum. Alas, the geologist was away; the rest of the staff listened to the news without interest. Then the former Socialist-Revolutionary gathered friends and began excavations. However, the bones lay at a depth of seven meters - the excavation had to be expanded. This required diggers, and for them - a salary. Vedenyapin turned to the authorities for help. The Gubernia Executive Committee went to meet him and gave him a hundred rubles. From funds intended for the improvement of the city.

The modern museum of dinosaurs in the village of Undory (Ulyanovsk region). Many plesiosaur bones have been found in local slate mines.

A few days later, the slope of the ravine gaped like a huge hole, and strange rumors spread around Penza. Someone claimed that a mammoth's grave was found near the cemetery. Someone said that the exile was digging an old sea frog. In one church, the priest during the service even told the flock about the stone bones left from the gigantic beast, which did not fit in Noah's ark. Rumors fueled curiosity, and daily people crowded in the ravine.

In the confusion, a couple of bones were stolen, and Vedenyapin asked the police to send a squad for protection. It did not help: several more vertebrae disappeared during the night. Then a Red Army patrol was posted in the ravine. Soldiers with three-line rifles were on duty around the clock. The main Penza newspaper Trudovaya Pravda also reined in the hooligans: between the notes about the insidious priests and where the butter and sugar had disappeared, there was a call: “A convincing request to those present not to interfere with the work and comply with the requirements of the leading excavators!”.

When 30 cubic meters of rock were thrown into the dump, the lower jaw appeared - long, with crooked teeth sticking out. It became clear that the remains of a giant marine reptile were found in the ravine - mosasaurus. The jaw was surrounded by a trench. It turned out to be a kind of table on which a bone covered with rock lay. They did not take it out, fearing to break it, and by telegram they asked the Academy of Sciences to send specialists.

Mosasaurus tooth from a private collection, Cretaceous layers of the Saratov region. Photo: Maxim Arkhangelsky

In the first days of September, two preparators of the Russian Geological Committee arrived in Penza and, according to the newspaper, immediately "began work on exposing the mosasaurus and excavating it." The bones had to be removed before the slope sank due to the rains. And the shooting range has been idle for half a month. For a couple of days, the find was cleared of the rock. 19 large, laterally flattened teeth protruded from the jaw. Three more teeth lay nearby. There was nothing else.

The jaw was packed in a large box and taken out on a cart to be sent to Leningrad. The regional museum was then presented with a plaster copy. As it turned out, the remains belonged to the giant, who lived at the end of the dinosaur era - Hoffmann's Mosasaurus (Mosasaurus hoffmanni), one of the last marine lizards. Mosasaurs were real colossi.

But they were not the only ones who lived in the Central Russian Sea, which existed on the territory of Central Russia in the Mesozoic era. During the Jurassic and Cretaceous periods of this era, many dynasties of lizards have changed. The bones of these leviathans are found not only in Penza, but also in the Moscow region, on the Kama and Vyatka, but most of all in the Volga region, a giant cemetery of sea giants.

The sea came to the eastern outskirts of Europe about 170 million years ago, in the middle of the Jurassic period. “The general rise in the level of the World Ocean in the Mesozoic era gradually led to the fact that the eastern part of Europe was under water. Then it was still not a sea, but rather a bay, stretching like a long tentacle from the south into the depths of the mainland. Later, the waves of the Boreal Sea moved from the north to the continent.

On the territory of the current Volga region, the bays met and formed a sea, which geologists called the Central Russian Sea, ”says Mikhail Rogov, senior researcher at the Geological Institute of the Russian Academy of Sciences. The western coast of the Central Russian Sea passed where Voronezh now stands, in the east it was bordered by the islands of the Urals. Thousands of square kilometers went under water - from the future Orenburg steppes to Vologda and Naryan-Mar.

Georgiasaurus Penza (georgiasaurus pensensis) Georgiasaurs grew up to 4-5 meters in length. Judging by the size and proportions of their limbs, they were quite strong swimmers and lived in the open sea. These lizards fed mainly on small fish and cephalopods, although they probably did not disdain carrion that floated on the surface of the sea. Their teeth are versatile: they can both pierce and tear prey.

The sea was shallow, no more than a few tens of meters deep. Numerous archipelagos and shoals rose from the water, teeming with fry and shrimps. Coniferous forests roared on the islands, dinosaurs roamed, and swimming lizards conquered the water element.

In the Jurassic, the marine predators that occupied the top of the food pyramid were ichthyosaurs and plesiosaurs. Their bones are found in shales on the banks of the Volga. Flat slate slabs, resembling a giant stone book, are often covered with imprints and shells as densely as this page is with letters. The bones of lizards were found especially often in the first third of the last century, when energy hunger came to the country and in the Volga region they switched to local fuel - oil shale. Like mushrooms after rain, grandiose underground labyrinths of mines appeared in Chuvashia, Samara, Saratov and Ulyanovsk regions.

Unfortunately, the miners were not interested in fossils. Usually the skeletons were destroyed during blasting, and the debris, along with the waste rock, went to the dump. Scientists have repeatedly asked the miners to save the bones, but this did little to help. Academician Yuri Orlov, director of the Paleontological Institute of the USSR Academy of Sciences, recalled how, during an expedition, he went to the workers at the mine and told them for a long time about the great value of ancient bones.

“Such finds as yours serve as an adornment of museums,” he said confidentially. To which the chief engineer replied: “Only rotozees go to museums ...”

Clydastes. These lizards preyed on cephalopods, fish and turtles. With their own length of up to five meters, they were not interested in large prey. Apparently, they mastered the technique of underwater flight, cutting through the water like penguins and sea turtles, and were excellent swimmers.

Some finds still managed to be preserved - thanks to local historians devoted to their work. One of these enthusiasts was Konstantin Zhuravlev. In 1931, near his hometown of Pugachev in the Saratov region, they began to develop shale - first in an open way, then in mines.

Soon, broken bones, broken fish prints and shells appeared in the dumps. Zhuravlev began to visit the mine often, climbed onto the dumps and talked with the workers, explaining to them how important fossils are. The miners promised to look closely at the breed and, if something interesting comes across, notify the museum. Sometimes, in fact, they were informed - but rarely and belatedly. The ethnographer collected almost the entire collection himself.

Basically, he came across the remains of ichthyosaurs. For several years, Zhuravlev found many scattered teeth and vertebrae of two ichthyosaurs - Paraophthalmosaurus Savelievsky(Paraophthalmosaurus saveljeviensis) and Ochevia, later named after the discoverer (Otschevia zhuravlevi).

They were medium sized lizards. They grew up to three or four meters long and, judging by the proportion of the body, were good swimmers, but probably preferred to hunt from ambush. At the time of the throw, they may have developed speeds of up to 30-40 kilometers per hour - quite sufficient to keep up with small fish or cephalopods, their main prey.

Once a real giant slipped away from Zhuravlev. At the end of the summer of 1932, he learned that the miners, laying a tunnel, for several days stumbled upon the huge vertebrae of the lizard - they were called "carriages". The miners did not attach any importance to this and threw everything away. Only one "carriage" has survived, which was given to the local historian. Zhuravlev calculated that the destroyed skeleton reached 10-12 meters in length. Subsequently, the vertebra disappeared, and it is impossible to verify the calculations. However, in the world there are skeletons and 14-meter fish-lizards.

To match these giants were jurassic plesiosaurs. Their remains are much rarer than ichthyosaur bones, and usually in the form of fragments. Once Zhuravlev picked up a half-meter fragment of the lower jaw from the dump, from which fragments of 20-centimeter teeth protruded.

Moreover, the surviving teeth were located in the back of the jaw, and one can only guess what kind of palisade adorned the mouth of this plesiosaur (the front teeth are much larger). The skull itself, apparently, was three meters high. A person would fit in it, as in a bed. Most likely, the jaw belonged Liopleurodon Russian(Liopleurodon rossicus) - one of the largest marine predators in the history of the Earth.

Lioprevrodon

“They grew up to 10-12 meters long, weighed 50 tons, but, judging by some bones, there were even larger individuals, including in the Volga region,” says Maxim Arkhangelsky, associate professor at Saratov State University. - Unfortunately, there are no complete skeletons or skulls in the collections. It's not just that they are rare. Sometimes they were simply destroyed during the extraction of shale.

Shortly after the end of the Great Patriotic War, the expedition of the Paleontological Institute discovered fragments of the skulls of two Liopleurodons in the dumps of mines in Buinsk (Chuvash Republic) and Ozinki (Saratov Region). Each piece is the size of a child.

Probably, a large skeleton found in the early 1990s in a mine near Syzran also belonged to Liopleurodon. Cracking open the shale, the combine's bucket hit a huge boulder. The teeth gnashed against its surface, sparks raining down. The worker got out of the cab and examined the obstacle - a large concretion, from which black, as if charred, bones protruded. The miner called the engineer. The work was suspended, local historians were called. They photographed the skeleton, but did not take it out, deciding that it would take a long time. The management of the mine supported them: the face was idle for a day. The find was surrounded by explosives and blown up...

new times

liopleurodons lived at the very end of the Jurassic period, when the Central Russian Sea reached its largest size. “Several million years later, in the Cretaceous period, the sea broke up into separate, often desalinated bays and either left or returned for a short time. A stable basin was preserved only in the south, reaching the borders of the current Middle and Lower Volga region, where a grandiose archipelago stretched: many islands with lagoons and sandbars, ”explains paleontologist, professor at Saratov University Evgeny Pervushov.

By that time, sea lizards had undergone great changes. The ichthyosaurs that swarm in the Jurassic seas almost died out. Their last representatives belonged to two genera - platipterygium(Platypterygius) and sveltonektes. A year ago, the first Russian sweltonectes(Sveltonectes insolitus), found in the Ulyanovsk region, is a two-meter fish-eating lizard.

The platipterygium was larger. One of the largest fragments was found 30 years ago in the vicinity of the Saratov village of Nizhnyaya Bannovka. From the high Volga cliff, with difficulty, they managed to pull out the narrow and long front part of the skull. Judging by its size, the lizard reached six meters in length. The bones were unusual. “There are extensive depressions on the frontal part of the skull, and a series of holes on the lower jaw. Dolphins have similar structures and are associated with echolocation organs. Probably, the Volga lizard could also navigate in the water, sending high-frequency signals and capturing their reflection, ”says Maxim Arkhangelsky.

But neither these nor other improvements helped the ichthyosaurs regain their former power. In the middle of the Cretaceous period, 100 million years ago, they finally left the arena of life, giving way to their longtime competitors - the plesiosaurs.

long neck

Ichthyosaurs lived only in water of normal salinity; desalinated bays or lagoons oversaturated with salt were not suitable for them. But the plesiosaurs did not care - they spread across a variety of sea basins. In the Cretaceous period, lizards with a long neck began to predominate among them. Last year, one of these giraffe lizards was described from the Lower Cretaceous deposits - abyssosaurus natalia(Abyssosaurus nataliae). Its scattered remains were dug up in Chuvashia. This plesiosaur got its name - Abyssosaurus ("lizard from the abyss") due to the structural features of the bones, which suggest that the seven-meter giant led a deep-sea lifestyle.

In the second half of the Cretaceous, among the plesiosaurs, there were giant elasmosaurs(Elasmosauridae) with an unusually long neck. They, apparently, preferred to live in shallow coastal waters, warmed by the sun and teeming with small living creatures. Biomechanical models show that elasmosaurs moved slowly and, most likely, like airships, hung motionless in the water column, bending their necks and collecting carrion, or fishing for fish and belemnites (extinct cephalopods) passing by.

We have not yet found complete elasmosaur skeletons, however, individual bones form large clusters: in places in the Lower Volga region, from one square meter, you can harvest a “harvest” of several teeth and half a dozen vertebrae the size of a fist.

Short necks lived with elasmosaurs plesiosaurs polycotylides(Polycotylidae). The skull of such a lizard was found in a small Penza quarry, where gray-yellow sandstone was mined and crushed. In the summer of 1972, a large slab with a strange convex pattern on the surface came across here. The workers were delighted: all around - clay, puddles, and the stove can be thrown at the change house and clean off the dirt from the soles of the boots. Once a worker, while wiping his feet, noticed that the strange lines add up to a whole picture - the head of a lizard.

On reflection, he called the local museum. Local historians came to the quarry, cleared the slab and were amazed to see an almost complete imprint of the skull, vertebral column and front flippers of the plesiosaur. To the question: "Where is the rest?" - the workers silently nodded towards the crusher. "Rug" moved to the museum. The bones were brittle and crumbled, but the imprints remained. According to them, a new, so far the only species of Russian polycotylids, the Penza Georgiasaurus (Georgiasaurus pensensis), was described.

Last year, paleontologists, thanks to a find by scientists at the Natural History Museum in Los Angeles, finally figured out that plesiosaurs were viviparous reptiles.

But plesiosaurs did not become the main marine predators of the end of the dinosaur era. The true masters of the seas were the mosasaurs, whose lizard ancestors descended into the sea in the middle of the Cretaceous. It is possible that the Volga region was their homeland: in Saratov, in an abandoned quarry on the slope of Bald Mountain, a fragment of the skull of one of the earliest mosasaurs was found. At the beginning of the 20th century, apparently, a complete skeleton of this lizard was dug up in the Saratov province. But it was not scientists who found it, but peasants.

They broke out blocks of bones and decided to sell them to the smelter. Such factories smoked all over the country. There, the remains of cows, horses and goats were used to make glue, soap and bone meal for fertilizer. Fossil remains were also not disdainful: the Ryazan ivory plant once bought four skeletons of large-horned deer for processing. But only the Saratov peasants thought of using the petrified lizard for soap ...

By the end of the Cretaceous period, mosasaurs settled all over the planet: their bones can now be found everywhere - in the American deserts, in the fields of New Zealand, in the quarries of Scandinavia. One of the richest locations was opened in the Volgograd region, not far from the Polunina farm, right on the collective farm melon.

In the middle of the cracked clods of hot earth, near the watermelons, there are dozens of rounded teeth and vertebrae of mosasaurs. Among them, the huge, brown banana-like teeth of Hoffmann's mosasaurs stand out - the very one next to which almost all other Cretaceous lizards looked like dwarfs.

Khans and kings of the Mesozoic era

Mosasaurus Hoffmann could be considered the largest Russian lizard, if not for the strange finds that are occasionally found in the Volga region. So, in the Ulyanovsk region, a fragment of the humerus of a Jurassic plesiosaur was once dug up - several times larger than usual. Then, in the Jurassic deposits of the Orenburg region, on the slope of Mount Khan's Tomb, a piece of a hefty "thigh" of a plesiosaur was found. The length of these two lizards, apparently, approached 20 meters.

That is, they could be compared with whales in size and were the largest predators in the entire history of the Earth. Another time, near an abandoned slate mine, a vertebra the size of a bucket was caught. Foreign experts considered it to be the bone of a huge dinosaur - titanosaur. However, one of the famous Russian experts on extinct reptiles, Saratov professor Vitaly Ochev, suggested that the vertebra could belong to a giant crocodile, under 20 meters long.

Unfortunately, scattered fragments are not always suitable for scientific description. It is only clear that the bowels of the Volga region hold many mysteries and will present more than one surprise to paleontologists. There may also be skeletons of the largest marine lizards on the planet.

National Geographic No. 4 2012.

Dinosaurs were the dominant vertebrates that inhabited all the ecosystems of planet Earth for over 160 million years - from the Triassic period (about 230 million years ago) to the end of the Cretaceous period (about 65 million years ago). I want to acquaint you with a list of the ten most ferocious marine dinosaurs.

10 Shastasaurus

Shastasaurus (Shastasaurus) - a genus of dinosaurs that lived at the end of the Triassic period (more than 200 million years ago) in the territory of modern North America and, possibly, China. His remains have been found in California, British Columbia and the Chinese province of Guizhou. This predator is the largest marine reptile ever found on the planet. It could grow up to 21 meters in length and weigh 20 tons.

9 Dacosaurus

In ninth place in the ranking is Dakosaurus, a marine crocodile that lived in the late Jurassic - early Cretaceous period (more than 100.5 million years ago). It was a fairly large, carnivorous animal, adapted almost exclusively to hunting large prey. Can grow up to 6 meters in length.

8. Thalassomedon

Thalassomedon is a genus of dinosaurs that lived in North America about 95 million years ago. Most likely, it was the main predator of its time. Thalassomedon grew up to 12.3 m in length. The size of its flippers reached about 1.5–2 meters. The length of the skull was 47 centimeters, teeth - 5 cm. He ate fish.

7. Nothosaurus

Nothosaurus (Nothosaurus) is a marine lizard that lived 240-210 million years ago in the territory of modern Russia, Israel, China and North Africa. In length reached about 4 meters. It had webbed limbs, with five long fingers that could be used both for movement on land and for swimming. Probably ate fish. A complete Nothosaurus skeleton can be seen at the Natural History Museum in Berlin.

6. Tylosaurus

In sixth place in the list of the most ferocious marine dinosaurs is Tylosaurus (Tylosaurus) - a large marine predatory lizard that inhabited the oceans at the end of the Cretaceous period (about 88-78 million years ago). It was the dominant marine predator of its time. It grew up to 14 m in length. It fed on fish, large predatory sharks, small mosasaurs, plesiosaurs, and waterfowl.

5. Talattoarchon

Talattoarchon (Thalattoarchon) - a large marine reptile that lived more than 245 million years ago in what is now the western part of the United States. The remains, consisting of part of the skull, spine, pelvic bones, and part of the hind fins, were discovered in Nevada in 2010. According to estimates, talattoarchon was the top predator of his time. It grew to at least 8.6 m in length.

4. Tanystropheus

Tanystropheus is a genus of lizard-like reptiles that lived in the Middle Triassic about 230 million years ago. It grew up to 6 meters in length, and was distinguished by a very elongated and mobile neck, which reached 3.5 m. It led a predatory aquatic or semi-aquatic lifestyle, probably hunting fish and cephalopods near the coast.

3. Liopleurodon

Liopleurodon (Liopleurodon) - a genus of large carnivorous marine reptiles that lived at the turn of the middle and late Jurassic period (from about 165 million to 155 million years ago). It is assumed that the largest known Liopleurodon was just over 10 m in length, but typical sizes for it range from 5 to 7 m (according to other sources, 16-20 meters). Body weight is estimated at 1-1.7 tons. These apex predators probably ambushed large cephalopods, ichthyosaurs, plesiosaurs, sharks, and other large animals they could catch.

2 Mosasaurus

Mosasaurus (Mosasaurus) is a genus of extinct reptiles that lived on the territory of modern Western Europe and North America during the Late Cretaceous - 70-65 million years ago. For the first time their remains were found in 1764 near the river Meuse. The total length of representatives of this genus ranged from 10 to 17.5 m. In appearance, they resembled a mixture of a fish (or a whale) with a crocodile. All the time they were in the water, plunging to a considerable depth. They ate fish, cephalopods, turtles and ammonites. According to some scientists, these predators are distant relatives of modern monitor lizards and iguanas.

1. Megalodon

Megalodon (Carcharocles megalodon) is an extinct species of prehistoric shark that lived throughout the oceans 28.1–3 million years ago. It is the largest known predatory fish in history. It is estimated that the megalodon reached 18 meters in length and weighed 60 tons. In body shape and behavior, it was similar to the modern white shark. He hunted cetaceans and other large marine animals. Interestingly, some cryptozoologists claim that this animal could have survived to the present, but apart from the found huge teeth (up to 15 cm in length), there is no other evidence that the shark still lives somewhere in the ocean.

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