Marine reptiles. Marine iguanas: photos, sizes, habits, interesting facts Family relations

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 with the help of 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, apparently, is consistent with the data we have on the movements of the plates of the earth's crust. 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 southern part 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 flourishing of reptiles in the Mesozoic era, which at first glance 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 the conditions environment have a decisive influence on the development of the animal world through natural selection.

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 they left on wet sand and silt (photo 18), on which the prints of three or four long fingers and another short, additional one, 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 bipedal predators 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 Ornitholestes dinosaur, featured two very interesting adaptations that enabled it to drive predatory image life. 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 deliver a strong kick to 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 changed 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 there was a huge heavy skull that stretched back in the form of 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 possessed 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 involuntarily wonder whether 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.

When studying life in the Mesozoic, perhaps the most striking thing is that almost half of all known species reptiles 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 an evolutionary backward step merely on the grounds that the Devonian fish emerged from the sea onto land and developed into reptiles 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 life and began to adapt to a new way of life. This adaptation went mainly along the path of improving the method of movement in 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 diverse 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 contents of the stomach of one of them, which, apparently, died before the stones in his stomach had time to crush the food he swallowed to the proper 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).

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, energy, and 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 sediments 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 were found in these deposits, in addition, similar remains were 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. Extraordinary good development the eyes and the part of the brain that controls vision were different.

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 for comparing the wing of a flying reptile, bat and birds. 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.

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 specific name Uthographica after the name 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 body's heat loss, 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 swimming 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 hunted fish in the same way that reptiles have consistently done since the beginning of the Mesozoic era.

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 established 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. Previously put forward explanations - illness, lack of food, and most vaguely - "loss of vitality"- completely unable to explain why there was a selective extinction of some of the inhabitants of land, sea and air, and not the complete extinction of the inhabitants of any one environment. It seems that 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.

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.

Incredible Facts

The modern ocean is home to many incredible creatures, many of which we have no idea about. You never know what lies there - in the dark cold depths. However, none of them can be compared with the ancient monsters that dominated the world's oceans millions of years ago.

In this article, we will tell you about pangolins, carnivorous fish and predatory whales that terrorized marine life in prehistoric times.

prehistoric world

Megalodon

The Megalodon may be the most famous creature on this list, but it's hard to imagine that a school bus-sized shark actually existed. Nowadays, there are many different scientific films and programs about these amazing monsters.

Contrary to popular belief, megalodons did not live at the same time as dinosaurs. They dominated the seas from 25 to 1.5 million years ago, which means that they missed the last dinosaur by 40 million years. In addition, this means that the first people found these sea monsters alive.

The home of the megalodon was the warm ocean that existed until the last ice age in the early Pleistocene, and it is believed that it was he who deprived these huge sharks of food and the opportunity to breed. Perhaps in this way nature has protected modern humanity from terrible predators.

Liopleurodon

If there was a water scene in the Jurassic Park movie that included several sea monsters of the time, the Liopleurodon would definitely appear in it. Despite the fact that scientists argue about the real length of this animal (some claim that it reached 15 meters), most of them agree that it was about 6 meters, with the pointed head of Liopleurodon occupying a fifth of the length.

Many people think that 6 meters is not so much, but the smallest representative of these monsters is able to swallow an adult. Scientists have recreated a model of Liopleurodon's fins and tested them.

In the course of their research, they found that these prehistoric animals were not so fast, but they were agile. They were also capable of making short, quick and sharp attacks similar to those of modern crocodiles, which makes them even more intimidating.

sea ​​monsters

Basilosaurus

Despite the name and appearance, they are not reptiles, as it might seem at first glance. In fact, these are real whales (and not the most intimidating in this squeak!). Basilosaurus were the predatory ancestors of modern whales and ranged from 15 to 25 meters in length. It is described as a whale, somewhat resembling a snake due to its length and ability to squirm.

It is hard to imagine that, while swimming in the ocean, one could stumble upon a huge creature that looked like a snake, a whale and a crocodile at the same time 20 meters long. The fear of the ocean would stick with you for a long time.

Physical evidence suggests that basilosaurs did not have the same cognitive abilities as modern whales. In addition, they did not have the ability to echolocate and could only move in two dimensions (which means that they could not actively dive and dive to great depths). Thus, this terrible predator was as stupid as a bag of prehistoric tools and would not be able to follow you if you dived or made landfall.

Racoscorpions

Not surprisingly, the words "sea scorpion" evoke only negative emotions, but this representative of the list was the most creepy of them. Jaekelopterus rhenaniae is a special species of crustacean that was the largest and most intimidating arthropod of the time: 2.5 meters of pure clawed terror under the shell.

Many of us are terrified of small ants or large spiders, but imagine the full range of fear experienced by a person who would not be lucky enough to meet this sea monster.

On the other hand, these creepy creatures became extinct even before the event that killed all dinosaurs and 90% of life on Earth. Only a few types of crabs survived, which are not so scary. There is no evidence that the ancient sea scorpions were venomous, but based on the structure of their tail, it can be concluded that this may indeed have been the case.

See also: A huge sea monster washed up on the coast of Indonesia

prehistoric animals

Mauisaurus

Mauisaurus was named after the ancient Maori god Maui, who, according to legend, pulled the skeleton of New Zealand from the bottom of the ocean with a hook, so that only by the name you can understand that this animal was huge. The neck of the Mauisaurus was about 15 meters long, which is quite a lot compared to its total length of 20 meters.

His incredible neck had many vertebrae, which gave it a special flexibility. Imagine a turtle without a shell with a surprisingly long neck - this is what this terrible creature looked like.

He lived during the Cretaceous period, which meant that the unfortunate creatures jumping into the water to escape the velociraptors and tyrannosaurs were forced to come face to face with these sea monsters. The habitats of the Mauisaurs were limited to the waters of New Zealand, which indicated that all the inhabitants were in danger.

Dunkleosteus

Dunkleosteus was a ten-meter predatory monster. Huge sharks lived much longer than dunkleostei, but this did not mean that they were the best predators. Instead of teeth, Dunkleosteus had bony growths, like some species of modern turtles. Scientists have calculated that their bite force was 1,500 kilograms per square centimeter, which put them on a par with crocodiles and tyrannosaurs and made them one of the creatures with the strongest bite.

Based on the facts about their jaw muscles, scientists concluded that the Dunkleosteus could open its mouth in one fiftieth of a second, absorbing everything in its path. As the fish matured, the single bony tooth plate was replaced by a segmented one, which made it easier to get food and bite through the thick shells of other fish. In the arms race called the prehistoric ocean, the Dunkleosteus was a real well-armoured, heavy tank.

Sea monsters and monsters of the deep

Kronosaurus

Kronosaurus is another short-necked lizard that looks like a Liopleurosaurus. Remarkably, its true length is also known only approximately. It is believed that it reached up to 10 meters, and its teeth reached up to 30 cm in length. That is why it was named after Kronos, the king of the ancient Greek titans.

Now guess where this monster lived. If your assumption was related to Australia, then you are absolutely right. The head of the Kronosaurus was about 3 meters long and it was able to swallow an entire adult human. In addition, after that, there was room inside the animal for another half.

Also, due to the fact that the flippers of kronosaurs were similar in structure to the flippers of a turtle, scientists concluded that they were very distantly related and assumed that kronosaurs also got out on land to lay their eggs. In any case, we can be sure that the nests of these sea ​​monsters no one dared to destroy.

Helicoprion

This shark, 4.5 meters long, had a serrated lower jaw lined with teeth. She looked like a hybrid shark with a buzz saw, and everyone knows that when dangerous power tools become part of a predator that is at the top of the food chain, the whole world trembles.

Helicoprion teeth were serrated, which clearly indicates the carnivorous nature of this sea ​​monster, however, scientists still do not know for certain whether the jaw was so pushed forward, as in the photo, or slightly pushed deep into the mouth.

These creatures survived the Triassic mass extinction, which could indicate their high intelligence, but the reason could also be their living in the deep sea.

prehistoric sea monsters

Leviathan Melvilla

Earlier in this article we already talked about predatory whales. Melville's Leviathan is the most intimidating of them all. Imagine a huge orca-sperm whale hybrid. This monster was not just carnivorous - it killed and ate other whales. It had the largest teeth of any animal known to us.

Their length sometimes reached 37 centimeters! They lived in the same oceans at the same time and ate the same food as megalodons, thus competing with the largest predatory shark of the time.

Their huge head was equipped with the same sonar devices as modern whales, making them more successful in murky waters. If it was not clear to someone from the very beginning, this animal was named after Leviathan - a giant sea monster from the Bible and Herman Melville, who wrote the famous "Moby Dick". If Moby Dick were one of the Leviathans, he would certainly eat the Pequod with his entire crew.

Temnodontosaurus, which lived about 200 million years ago, had eyes of a unique size. Their diameter was 26 centimeters with an almost two-meter skull size of this lizard.
Thanks to the findings of recent years, the study of Mesozoic marine lizards, which for a long time remained in the shadow of their distant terrestrial relatives - dinosaurs, is experiencing a real renaissance. Now we can quite confidently reconstruct the appearance and habits of giant aquatic reptiles - ichthyosaurs, pliosaurs, mosasaurs and plesiosaurs.

The skeletons of aquatic reptiles were among the first to become known to science, having played an important role in the development of the theory of biological evolution. The massive jaws of a mosasaurus, found in 1764 in a quarry near the Dutch city of Maastricht, clearly confirmed the fact of the extinction of animals, which for that time was a radically new idea. And at the beginning of the 19th century, the finds of ichthyosaur and plesiosaur skeletons made by Mary Anning in southwestern England provided rich material for research in the field of the still emerging science of extinct animals - paleontology. Nowadays, marine species of reptiles are saltwater crocodiles, sea ​​snakes and turtles, as well as Galapagos iguana lizards - make up only a small fraction of the reptiles that live on the planet. But in the Mesozoic era (251-65 million years ago), their number was incomparably greater. This, apparently, was favored by a warm climate, which allowed animals unable to maintain a constant body temperature to feel great in water - an environment with a high heat capacity. In those days, sea lizards plied the seas from pole to pole, occupying the ecological niches of modern whales, dolphins, seals and sharks. For more than 190 million years, they constituted a "caste" of top predators, hunting not only for fish and cephalopods but also to each other.

Kronosaurus was the terror of the seas of the Early Cretaceous (125–99 million years ago) and one of the largest marine reptiles of all time. He was named after Kronos, one of the ancient Greek titans.
Back in the water

Like aquatic mammals - whales, dolphins and pinnipeds, sea lizards descended from air-breathing terrestrial ancestors: 300 million years ago, it was reptiles that conquered the land, having managed, thanks to the emergence of eggs protected by a leathery shell (unlike frogs and fish), to switch from reproduction to water to reproduction outside the aquatic environment. Nevertheless, for one reason or another, then one or another group of reptiles at different periods again “tried their luck” in the water. It is not yet possible to specify exactly these reasons, but, as a rule, the development of a new niche by a species is explained by its unemployment, the presence of food resources, and the absence of predators.

The real invasion of the pangolins into the ocean began after the largest Permian-Triassic extinction in the history of our planet (250 million years ago). Experts still argue about the causes of this catastrophe. are being put forward different versions: the fall of a large meteorite, intense volcanic activity, a massive release of methane hydrate and carbon dioxide. One thing is clear - for an extremely short period of time by geological standards, out of the whole variety of species of living organisms, only one in twenty managed to avoid becoming a victim of an ecological catastrophe. empty warm seas provided to the "colonialists" great opportunities, and this is probably why several groups of marine reptiles arose at once in the Mesozoic era. Four of them were truly unparalleled in number, diversity and distribution. Each of the groups - ichthyosaurs, plesiosaurs, their relatives pliosaurs, as well as mosasaurs - consisted of predators that occupied the tops of the food pyramids. And each of the groups spawned colossi of truly monstrous proportions.

The most important factor that determined the successful development of the Mesozoic reptiles of the aquatic environment was the transition to live birth. Instead of laying eggs, females gave birth to fully formed and fairly large cubs, thereby increasing their chances of survival. Thus, the life cycle of the reptiles in question now took place entirely in the water, and the last thread connecting sea lizards with land was broken. In the future, apparently, it was this evolutionary acquisition that allowed them to leave shallow waters and conquer the open sea. The lack of need to go ashore lifted size restrictions, and some of the marine reptiles took advantage of gigantism. Growing up big is not easy, but if you have grown up, try to overcome this. He will offend anyone.

Shonisaurus is the largest marine reptile in the history of evolution, which is over 200 million years old. Such a whopper weighed up to 40 tons. Probably, small schooling fish and squid served as food for her.
Ichthyosaurs - Bigger, Deeper, Faster

The ancestors of fish lizards, ichthyosaurs, who mastered the aquatic environment about 245 million years ago, were medium-sized inhabitants of shallow waters. Their body was not barrel-shaped, as in the descendants, but elongated, and its bending played an important role in movement. However, over the course of 40 million years, the appearance of ichthyosaurs changed significantly. The originally elongated body became more compact and perfectly streamlined, and the caudal fin with a large lower lobe and a small upper lobe in most species was transformed into an almost symmetrical one.

Paleontologists can only guess about the family ties of ichthyosaurs. It is believed that this group separated very early from the evolutionary trunk, which subsequently gave rise to such branches of reptiles as lizards and snakes, as well as crocodiles, dinosaurs and birds. One of the main problems still remains the lack of a transitional link between the terrestrial ancestors of ichthyosaurs and primitive marine forms. First known to science fish lizards are already completely aquatic organisms. What was their ancestor, while it is difficult to say.

The length of the neck of elasmosaurs, who lived 100 million years ago, often exceeded the total length of their body and tail. The neck was their main tool for hunting fish and cephalopods.

The length of most ichthyosaurs did not exceed 2–4 meters. However, among them were giants, reaching 21 meters. Such hulks included, for example, shonisaurs, who lived at the end Triassic period, about 210 million years ago. These are some of the largest marine animals that have ever lived in the oceans of our planet. In addition to their huge size, these ichthyosaurs were distinguished by a very long skull with narrow jaws. To imagine Shonisaurus, as one American paleontologist joked, you have to inflate a huge rubber dolphin and stretch its muzzle and fins strongly. The most interesting thing is that only the young had teeth, while the gums of adult reptiles were toothless. You ask: how did such colossi eat? This can be answered: if shonisaurs were smaller, then one could assume that they chased prey and swallowed it whole, as swordfish and its relatives, marlin and sailfish, do. However, twenty-meter giants could not be fast. Perhaps they satiated themselves with small schooling fish or squid. There is also an assumption that adult shonisaurs used a filtration apparatus like a whalebone, which allowed them to strain plankton from the water. By the beginning of the Jurassic period (200 million years ago), ichthyosaur species appeared in the seas, relying on speed. They deftly pursued fish and swift belemnites - extinct relatives of squid and cuttlefish. According to modern calculations, a three-four-meter ichthyosaur stenopterygius developed a cruising speed no less than one of the fastest fish, tuna (dolphins swim twice as slowly), almost 80 km / h or 20 m / s! In water! The main mover of such champions was a powerful tail with vertical blades, like a fish.

In the Jurassic period, which became the golden age of ichthyosaurs, these lizards were the most numerous marine reptiles. Some species of ichthyosaurs in search of prey could dive to a depth of half a kilometer or more. These reptiles could distinguish moving objects at such a depth due to the size of their eyes. So, in the darkdontosaurus, the diameter of the eye was 26 centimeters! More (up to 30 centimeters) - only giant squid. From deformations during rapid movement or at great depths, the eyes of ichthyosaurs were protected by a kind of eye skeleton - supporting rings, consisting of more than a dozen bone plates developing in the shell of the eye - the sclera.

The elongated muzzle, narrow jaws and shape of the teeth of the fish lizards indicate that they ate, as already mentioned, relatively small animals: fish and cephalopods. Some species of ichthyosaurs had sharp, conical teeth that were good for grabbing nimble, slippery prey. In contrast, other ichthyosaurs had wide, blunt or rounded teeth to crush the shells of cephalopods such as ammonites and nautilids. However, not so long ago, the skeleton of a pregnant female ichthyosaur was discovered, inside which, in addition to fish bones, they found the bones of young sea turtles and, most surprisingly, the bone of an ancient sea bird. There is also a report about the discovery of the remains of a pterosaur (flying pangolin) in the belly of a fish lizard. And this means that the diet of ichthyosaurs was much more diverse than previously thought. Moreover, one of the species of early fish lizards discovered this year, which lived in the Triassic (about 240 million years ago), the edges of the rhombic teeth in the cross section were serrated, which indicates its ability to tear pieces from prey. Such a monster, reaching a length of 15 meters, had practically no dangerous enemies. However, this branch of evolution, for unclear reasons, stopped in the second half of the Cretaceous period, about 90 million years ago.

In the bones of tylosaurs that lived 90-65 million years ago, traces of necrosis were found. As a rule, such pathologies are characteristic of animals diving to great depths.
Plesiosaurs and pliosaurs are dissimilar relatives

In the shallow waters of the seas of the Triassic period (240-210 million years ago), another group of reptiles flourished - notosaurs. In their way of life, they most of all resembled modern seals, spending part of their time on the shore. Nothosaurs were characterized by an elongated neck, and they swam with the help of a tail and webbed feet. Gradually, in some of them, the paws were replaced by fins, which were used as oars, and the more powerful they were, the more the role of the tail weakened.

Nothosaurs are considered to be the ancestors of the plesiosaurs, which the reader is well aware of from the legend of the monster from Loch Ness. The first plesiosaurs appeared in the middle of the Triassic (240-230 million years ago), but the beginning of their heyday falls on the beginning of the Jurassic period, that is, about 200 million years ago.

Then the pliosaurs appeared. These marine reptiles were close relatives, but they looked different. Representatives of both groups - a case unique among aquatic animals - moved with the help of two pairs of large paddle-shaped fins, and their movements were probably not unidirectional, but multidirectional: when the front fins moved down, the rear ones moved up. It can also be assumed that only the front fin blades were used more often - this way more energy was saved. The rear ones were connected to work only during throws for prey or rescue from larger predators.

Plesiosaurs are easily recognizable by their very long necks. So, for example, in Elasmosaurus, it consisted of 72 vertebrae! Scientists even know skeletons whose neck is longer than the body and tail combined. And, apparently, it was the neck that was their advantage. Let plesiosaurs were not the fastest swimmers, but the most maneuverable. By the way, with their disappearance, long-necked animals no longer appeared in the sea. And one more interesting fact: the skeletons of some plesiosaurs were found not in marine, but in estuarine (where rivers flowed into the seas) and even freshwater sedimentary rocks. Thus, it is clear that this group did not live exclusively in the seas. For a long time it was believed that plesiosaurs fed mainly on fish and cephalopods (belemnites and ammonites). The lizard slowly and imperceptibly swam up to the flock from below from behind and, thanks to its extra long neck, snatched out prey, clearly visible against the bright sky, before the flock rushed to its heels. But today it is obvious that the diet of these reptiles was richer. The found skeletons of plesiosaurs often contain smooth stones, probably specially swallowed by the lizard. Experts suggest that it was not ballast, as previously thought, but real millstones. The muscular section of the stomach of the animal, contracting, moved these stones, and they crushed strong shells of mollusks and shells of crustaceans that fell into the womb of a plesiosaur. Skeletons of plesiosaurs with the remains of benthic invertebrates indicate that, in addition to species that specialized in hunting in the water column, there were also those that preferred, swimming near the surface, to collect prey from the bottom. It is also possible that some plesiosaurs could switch from one type of food to another depending on its availability, because the long neck is a great "fishing rod" with which you could "catch" a variety of prey. It is worth adding that the neck of these predators was a rather rigid structure, and they could not sharply bend or lift it out of the water. This, by the way, calls into question many stories about the Loch Ness monster, when eyewitnesses report that they saw exactly a long neck sticking out of the water. The largest of the plesiosaurs is the New Zealand Mauisaurus, which reached 20 meters in length, almost half of which was a giant neck.

The first pliosaurs, who lived in the late Triassic and early Jurassic periods (about 205 million years ago), strongly resembled their plesiosaur relatives, initially misleading paleontologists. Their heads were relatively small, and their necks were rather long. Nevertheless, by the middle of the Jurassic, the differences became very significant: the main trend in their evolution was an increase in the size of the head and the power of the jaws. The neck, accordingly, became short. And if plesiosaurs hunted mainly for fish and cephalopods, then adult pliosaurs chased other marine reptiles, including plesiosaurs. By the way, they also did not disdain carrion.

The largest of the first pliosaurs was the seven-meter rhomaleosaurus, but its size, including the size of its meter-long jaws, pales in comparison with the monsters that appeared later. In the oceans of the second half of the Jurassic period (160 million years ago), lyopleurodons were in charge - monsters that could reach 12 meters in length. Later, in the Cretaceous period (100-90 million years ago), colossi of similar sizes lived - kronosaurs and brachaucheniuses. However, the largest were the pliosaurs of the late Jurassic period.

Liopleurodons, who inhabited the depths of the sea 160 million years ago, could move quickly with the help of large flippers, which they flapped like wings.
Even more?!

Recently, paleontologists have been unspeakably lucky with sensational finds. So, two years ago, a Norwegian expedition led by Dr. Jorn Khurum removed fragments of the skeleton of a giant pliosaurus from the permafrost on the island of Svalbard. Its length was calculated from one of the bones of the skull. It turned out - 15 meters! And last year, in the Jurassic deposits of Dorset County in England, scientists were waiting for another success. On one of the beaches of Weymouth Bay, local fossil collector Kevin Sheehan dug up an almost completely preserved huge skull measuring 2 meters 40 centimeters! The length of this "sea dragon" could be as much as 16 meters! Almost the same was the length of a young pliosaurus found in 2002 in Mexico and named the Monster of Aramberri.

But that's not all. The Oxford University Museum of Natural History houses a giant lower jaw of a macromerus pliosaurus, the size of which is 2 meters 87 centimeters! The bone is damaged, and it is believed that its total length was no less than three meters. Thus, its owner could reach 18 meters. Truly imperial size.

But pliosaurs were not just huge, they were real monsters. If anyone posed a threat to them, it was they themselves. Yes, the huge, whale-like ichthyosaur schonisaurus and the long-necked plesiosaur mauisaur were longer. But the colossal predators of the pliosaurs were ideal "killing machines" and had no equal. Three-meter fins rapidly carried the monster to the target. Powerful jaws, palisaded with huge banana-sized teeth, crushed the bones and tore the flesh of the victims, regardless of their size. They were truly invincible, and if anyone can be compared with them in power, it is the fossil megalodon shark. Tyrannosaurus rex next to giant pliosaurs looks like a pony in front of a Dutch heavy truck. Taking a modern crocodile for comparison, paleontologists calculated the pressure that the jaws of a huge pliosaurus developed at the time of the bite: it turned out to be about 15 tons. The idea of ​​\u200b\u200bthe power and appetite of an eleven-meter kronosaurus that lived 100 million years ago was obtained by scientists by “looking” into its belly. There they found the bones of a plesiosaur.

Throughout the Jurassic and most of the Cretaceous, plesiosaurs and pliosaurs were the dominant ocean predators, although it should not be forgotten that sharks were always around. One way or another, large pliosaurs became extinct about 90 million years ago for unclear reasons. However, as you know, a holy place is never empty. They were replaced in the seas of the late Cretaceous by giants that could compete with the most powerful of the pliosaurs. We are talking about mosasaurs.

Mosasaurus mosasaurus - lunch

The group of mosasaurs, which replaced, and perhaps replaced the pliosaurs and plesiosaurs, arose from an evolutionary branch close to monitor lizards and snakes. Mosasaurs who completely switched to life in water and became viviparous had their legs replaced by fins, but the main mover was a long flattened tail, and in some species it ended in a shark-like fin. It can be noted that, judging by the pathological changes found in the fossilized bones, some mosasaurs were able to dive deep and, like all extreme divers, suffered from the consequences of such diving. Some species of mosasaurs fed on benthic organisms, crushing mollusk shells with short, wide teeth with rounded tops. However, the conical and slightly recurved terrible teeth of most species leave no doubt about the food habits of their owners. They hunted fish, including sharks, and cephalopods, crushed turtle shells, swallowed sea ​​birds and even flying lizards, tore apart other marine reptiles and each other. So, half-digested bones of a plesiosaur were found inside a nine-meter tylosaurus.

The design of the skull of mosasaurs allowed them to swallow whole even very large prey: like snakes, their lower jaw was equipped with additional joints, and some bones of the skull articulated movably. As a result, the open mouth was truly monstrous in size. Moreover, two additional rows of teeth grew in it on the palate, which made it possible to hold prey more firmly. However, do not forget that mosasaurs were also hunted. The skull of a five-meter Tylosaurus found by paleontologists was crushed. The only one who could do that was another, larger mosasaurus.

For 20 million years, mosasaurs evolved rapidly, giving giants comparable in mass and size to monsters from other groups of marine reptiles. By the end of the Cretaceous period, during the next great extinction, giant sea lizards disappeared along with dinosaurs and pterosaurs. Possible causes of a new environmental catastrophe could be the impact of a huge meteorite and (or) increased volcanic activity.

The first, and even before the Cretaceous extinction, were the pliosaurs, and somewhat later, the plesiosaurs and mosasaurs. It is believed that this happened due to a violation of food chains. The domino principle worked: the extinction of some mass groups of unicellular algae led to the disappearance of those who fed on them - crustaceans, and, as a result, fish and cephalopods. Marine reptiles were at the top of this pyramid. The extinction of mosasaurs, for example, could be due to the extinction of ammonites, which formed the basis of their diet. However, there is no final clarity on this issue. For example, two other groups of predators, sharks and bony fish that also fed on ammonites, survived the Late Cretaceous extinction era with relatively few losses.

Whatever it was, but the era of sea monsters is over. And only after 10 million years, sea giants will reappear, but not lizards, but mammals - the descendants of the wolf-like pakicetus, the first to master the coastal shallow water. Modern whales lead their pedigree from it.

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 an evolutionary backward step merely on the grounds that the Devonian fish emerged from the sea onto land and developed into reptiles 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 diverse 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 contents of the stomach of one of them, which, apparently, died before the stones in his stomach had time to crush the food he swallowed to the proper 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).

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 only meet boys running 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 writes notes in the journal "Katorga 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, during the service, the priest 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 age of dinosaurs - 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 Central Russia during 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 the sea, but rather the bay, long tentacle stretching from the south into the interior of the mainland. Later, the waves of the Boreal Sea moved from the north to the continent.

On the territory of the present Volga region, the bays met and formed a sea, which geologists called the Central Russian Sea, ”says a senior researcher at the Geological Institute Russian Academy Sciences Mikhail Rogov. The western coast of the Central Russian Sea passed where Voronezh now stands, in the east it was bordered by the Ural islands. 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 Yury Orlov, director of the Paleontological Institute of the USSR Academy of Sciences, recalled how during the 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 they 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.

Soon after the end of the Great Patriotic War, the expedition of the Paleontological Institute discovered in the dumps of mines in Buinsk ( Chuvash Republic) and Ozinki (Saratov region) fragments of the skulls of two Liopleurodons. 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 pangolin 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.

Complete skeletons of elasmosaurs have not yet been found in our country, however, individual bones form large clusters: in some places in the Lower Volga region from one square meter you can harvest a few teeth and half a dozen fist-sized vertebrae.

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: there was clay, puddles all around, and they could throw the stove at the change house and clean off the dirt from the soles of their 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 discovery 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 in Saratov province dug up, apparently, the complete skeleton of this lizard. 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 factory 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 discovered in 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 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 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, disparate 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 sea pangolins on the planet.

National Geographic No. 4 2012.