Ancient sea lizards. Marine iguanas: photos, sizes, habits, interesting facts
Thanks to the discoveries of recent years, the study of sea lizards of the Mesozoic, for a long time remaining 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 became known to science among the first, playing 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 was a radically new idea at that time. And in early XIX centuries, discoveries of skeletons of ichthyosaurs and plesiosaurs made by Mary Anning in southwestern England provided rich material for research in the still emerging field of the science of extinct animals - paleontology.
Nowadays, marine reptile species - saltwater crocodiles, sea snakes and turtles, and Galapagos iguana lizards - make up only a small proportion of the reptiles living on the planet. But in the Mesozoic era (251-65 million years ago) their number was incomparably greater. This, apparently, was favored by the warm climate, which allowed animals incapable of maintaining a constant body temperature to feel great in water, an environment with a high heat capacity. In those days, sea lizards roamed the seas from pole to pole, occupying the ecological niches of modern whales, dolphins, seals and sharks. For more than 190 million years, they formed a “caste” of top predators, hunting not only fish and cephalopods, but also each other.
Back in the water
Like aquatic mammals - whales, dolphins and pinnipeds, sea lizards descended from air-breathing land-based ancestors: 300 million years ago, it was reptiles that conquered land, managing, thanks to the appearance of eggs protected by a leathery shell (unlike frogs and fish), to move from reproduction to water to reproduce outside the aquatic environment. Nevertheless, for one reason or another, one or another group of reptiles at different periods again “tried their luck” in the water. It is not yet possible to accurately indicate these reasons, but, as a rule, the development of a new niche by a species is explained by its unoccupied position, the availability of food resources and the absence of predators.
The real invasion of lizards into the ocean began after the largest Permian-Triassic extinction event in the history of our planet (250 million years ago). Experts are still arguing about the causes of this disaster. Moving forward different versions: the fall of a large meteorite, intense volcanic activity, massive release of methane hydrate and carbon dioxide. One thing is clear: over a period of time that is extremely short by geological standards, out of all the diversity of species of living organisms, only one in twenty managed to avoid becoming a victim of an environmental disaster. The empty warm seas provided the “colonizers” with great opportunities, and this is probably why in Mesozoic era Several groups of marine reptiles arose at once. Four of them were truly unparalleled in number, diversity and distribution. Each group - ichthyosaurs, plesiosaurs, their relatives the pliosaurs, and mosasaurs - consisted of predators that occupied the top of the food pyramids. And each of the groups gave birth to colossi of truly monstrous proportions.
The most important factor that determined the successful development of the aquatic environment by Mesozoic reptiles was the transition to viviparity. Instead of laying eggs, females gave birth to fully formed and fairly large young, thereby increasing their chances of survival. Thus, the life cycle of the reptiles discussed here now took place entirely in the water, and the last thread connecting the sea lizards with the land was broken. Subsequently, apparently, it was this evolutionary acquisition that allowed them to leave shallow waters and conquer the open sea. Not having to go ashore removed size restrictions, and some marine reptiles took advantage of gigantism. Growing up big isn't easy, but once you've grown up, try to beat him. He will offend anyone himself.
Ichthyosaurs - bigger, deeper, faster
The ancestors of fish-lizard ichthyosaurs, who mastered the aquatic environment about 245 million years ago, were small inhabitants of shallow waters. Their body was not barrel-shaped, like those of their descendants, but elongated, and its bending played an important role in movement. However, within 40 million years appearance ichthyosaurs changed significantly. The initially elongated body became more compact and ideally streamlined, and the caudal fin with a large lower blade and a small upper one in most species was transformed into almost symmetrical.
Paleontologists can only guess about the family relationships of ichthyosaurs. It is believed that this group separated very early from the evolutionary trunk, which later 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. It is difficult to say what their ancestor was.
The length of most ichthyosaurs did not exceed 2–4 meters. However, among them there were also giants, reaching 21 meters. Such giants included, for example, Shonisaurs, who lived at the end of the 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 enormous size, these ichthyosaurs were distinguished by a very long skull with narrow jaws. To imagine a shonisaurus, as one American paleontologist joked, you need to inflate a huge rubber dolphin and greatly stretch its face and fins. The most interesting thing is that only the young had teeth, while the gums of the adult reptiles were toothless. You may ask: how did such colossi eat? To this we can answer: if Shonisaurs were smaller, then one could assume that they chased prey and swallowed it whole, as do swordfish and its relatives - marlin and sailfish. However, twenty-meter giants could not be fast. Perhaps they saturated 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. Back to top Jurassic period(200 million years ago), species of ichthyosaurs appeared in the seas, relying on speed. They deftly pursued fish and swift belemnites - extinct relatives of squids and cuttlefish. According to modern calculations, the three- to four-meter ichthyosaur stenopterygius developed a cruising speed no less than one of the fastest fish, tuna (dolphins swim twice as slow) - almost 80 km/h or 20 m/s! In water! The main propellant of such record holders was a powerful tail with vertical blades, like those of fish.
In the Jurassic period, which became the golden age of ichthyosaurs, these lizards were the most numerous marine reptiles. Some species of ichthyosaurs could dive to depths of up to half a kilometer or more in search of prey. These reptiles could distinguish moving objects at such a depth due to the size of their eyes. So, the diameter of the eye of Temnodontosaurus was 26 centimeters! More (up to 30 centimeters) - only giant squid. The eyes of ichthyosaurs were protected from deformation during rapid movement or at great depth by a peculiar 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 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 broad teeth with blunt or rounded tips 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 seabird. There is also a report of the discovery of remains of a pterosaur (flying lizard) in the belly of a fish lizard. 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), had serrated edges of the rhombic cross-section of its teeth, which indicates its ability to tear off pieces from prey. Such a monster, which reached a length of 15 meters, had practically no dangerous enemies. However, for unclear reasons, this branch of evolution stopped in the second half of the Cretaceous period, about 90 million years ago.
In the shallow seas of the Triassic period (240–210 million years ago), another group of reptiles flourished - the nothosaurs. In their lifestyle, they most closely 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, some of them replaced their paws with fins, which were used as oars, and the more powerful they were, the more the role of the tail weakened.
Nothosaurs are considered the ancestors of plesiosaurs, which the reader knows well from the legend of the monster from Loch Ness. The first plesiosaurs appeared in the mid-Triassic (240–230 million years ago), but their heyday began at the beginning of the Jurassic period, that is, about 200 million years ago.
At the same time, pliosaurs appeared. These marine reptiles were closely related, but they looked different. Representatives of both groups - a unique case 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 fins moved up. It can also be assumed that only the front fin blades were used more often - this saved more energy. The hind ones were put to work only during attacks on prey or rescue from larger predators.
Plesiosaurs are easily recognized by their very long necks. For example, in Elasmosaurus it consisted of 72 vertebrae! Scientists even know skeletons whose necks are longer than the body and tail combined. And, apparently, it was the neck that was their advantage. Although plesiosaurs were not the fastest swimmers, they were 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 and, thanks to its extremely long neck, snatched the prey, clearly visible against the background of the light 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 animal’s stomach, contracting, moved these stones, and they crushed the strong shells of mollusks and crustacean shells that had fallen into the womb of the plesiosaur. Skeletons of plesiosaurs with remains of bottom invertebrates indicate that in addition to species that specialized in hunting in the water column, there were also those that preferred to swim near the surface and 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 a long neck is an excellent “fishing rod” with which it was possible to “catch” a wide 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, casts doubt on 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, which lived in the late Triassic and early Jurassic periods (about 205 million years ago), closely resembled their plesiosaur relatives, initially misleading paleontologists. Their heads were relatively small, and their necks were quite long. Nevertheless, by the middle of the Jurassic period, 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 didn’t disdain carrion either.
The largest of the first pliosaurs was the seven-meter Romaleosaurus, but its size, including the size of its meter-long jaws, pales in comparison with the monsters that appeared later. The oceans of the second half of the Jurassic period (160 million years ago) were ruled by Liopleurodons - monsters that may have reached 12 meters in length. Later, in the Cretaceous period (100–90 million years ago), colossi of similar sizes lived - Kronosaurus and Brachauchenius. However, the largest pliosaurs were the Late Jurassic period.
Liopleurodons, which 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?!
IN Lately paleontologists are incredibly lucky to make sensational finds. Thus, two years ago, a Norwegian expedition led by Dr. Jorn Hurum extracted fragments of the skeleton of a giant pliosaur from the permafrost on the island of Spitsbergen. Its length was calculated from one of the skull bones. It turned out - 15 meters! And last year, in the Jurassic sediments of Dorset County in England, scientists had 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 length was the juvenile pliosaur found in 2002 in Mexico and named the Monster of Aramberri.
But that's not all. In the museum natural history Oxford University houses a giant lower jaw of a macromerus pliosaur, 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 sizes.
But pliosaurs were not just huge, they were real monsters. If anyone posed a threat to them, it was themselves. Yes, the huge, whale-like Shonisaurus ichthyosaur and the long-necked Mauisaurus plesiosaur were longer. But the colossal pliosaur predators were ideal “killing machines” and had no equal. Three-meter fins quickly carried the monster towards the target. Powerful jaws with a palisade of huge teeth the size of bananas crushed bones and tore the flesh of victims, regardless of their size. They were truly invincible, and if anyone can be compared with them in power, it was the fossil megalodon shark. Tyrannosaurus rex next to giant pliosaurs looks like a pony in front of a Dutch draft horse. Taking a modern crocodile for comparison, paleontologists calculated the pressure that the huge pliosaur’s jaws developed at the time of the bite: it turned out to be about 15 tons. Scientists got an idea of the power and appetite of the eleven-meter Kronosaurus, who lived 100 million years ago, by “looking” into its belly. There they found the bones of a plesiosaur.
Throughout the Jurassic and much of the Cretaceous period, plesiosaurs and pliosaurs were the dominant ocean predators, although it should not be forgotten that there were always sharks nearby. One way or another, large pliosaurs went 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 to mosasaurus - lunch
The group of mosasaurs, which replaced and perhaps supplanted the pliosaurs and plesiosaurs, arose from an evolutionary branch close to monitor lizards and snakes. In mosasaurs that completely switched to life in water and became viviparous, their paws were replaced by fins, but the main mover was a long, flattened tail, and in some species it ended in a fin like a shark’s. It can be noted that, judging by the pathological changes found in the fossilized bones, some mosasaurs were able to dive deeply and, like all extreme divers, suffered from the consequences of such dives. Some species of mosasaurs fed on benthic organisms, crushing mollusk shells with short, wide teeth with rounded tops. However, the conical and slightly bent back terrible teeth of most species leave no doubt about the eating habits of their owners. They hunted fish, including sharks, and cephalopods, crushed turtle shells, swallowed seabirds and even flying lizards, and tore apart other marine reptiles and each other. Thus, half-digested plesiosaur bones were found inside a nine-meter-long tylosaur.
The design of the skull of mosasaurs allowed them to swallow even very large prey whole: like snakes, their lower jaw was equipped with additional joints, and some bones of the skull were articulated movably. As a result, the open mouth was truly monstrous in size. Moreover, two additional rows of teeth grew on the roof of the mouth, making it possible to hold prey more firmly. However, we should not forget that mosasaurs were also hunted. The five-meter-long Tylosaurus found by paleontologists had a crushed skull. The only one who could do this was another, larger mosasaurus.
Over 20 million years, mosasaurs rapidly evolved, giving rise to giants comparable in mass and size to monsters from other groups of marine reptiles. Towards 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 disaster could be the impact of a huge meteorite and (or) increased volcanic activity.
The first to disappear, even before the Cretaceous extinction, were the pliosaurs, and somewhat later the plesiosaurs and mosasaurs. It is believed that this happened due to a disruption in the food chain. The domino principle has worked: the extinction of some mass groups single-celled algae led to the disappearance of those who fed on them - crustaceans, and, as a consequence, fish and cephalopods. Marine reptiles were at the top of this pyramid. The extinction of mosasaurs, for example, could be a consequence of 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 teleosts, which also fed on ammonites, survived the Late Cretaceous extinction event with relatively few losses.
Be that as it may, but the era sea monsters ended. And only after 10 million years will they appear again sea giants, but no longer lizards, but mammals - descendants of the wolf-like Pakicetus, which was the first to master the coastal shallow waters. Modern whales trace their ancestry from him. However, that's another story. Our magazine talked about this in the first issue of 2010.
The Volga region preserves the remains of giants who roamed the seas during the time of dinosaurs.
Early on an August morning in 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 modern times. Mikhail Vedenyapin. He went down into the Prolom ravine, to a small machine-gun firing range. There were no exercises that day, and in the ravine you could only meet boys running to collect shell casings.
Mikhail Vedenyapin had been living in Penza for two years, in exile. Before that, the tsarist courts exiled him, Admiral Kolchak promised to shoot him, and now the Bolsheviks did not like his views. And so the former professional revolutionary Socialist Revolutionary works as a statistician, in his spare time he writes notes in the magazine “Katorga and Exile” and wanders around the surrounding area in search of fossils. Like many scientists and simply curious people of those times, he has ten years left to live...
He walked along the slope of a deep ravine, picking up shells of mollusks from the ground that lived in a sea that had long ago disappeared - more than 80 million years ago. In one place, a sandy slope was broken by a machine-gun burst, 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. It didn’t take long to search: huge bones were sticking 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 Social Revolutionary gathered his friends and began excavations. However, the bones lay at a depth of seven meters - the excavation needed to be expanded. This required diggers, and for them - a salary. Vedenyapin turned to the authorities for help. The provincial executive committee met him halfway and gave him a hundred rubles. From funds intended for the improvement of the city.
Modern dinosaur museum in the village of Undory (Ulyanovsk region). Many plesiosaur bones have been found in local shale mines.
A few days later, the slope of the ravine gaped like a huge hole, and strange rumors spread throughout Penza. Someone claimed that a mammoth's grave was found near the cemetery. Someone said that the exile was digging up an ancient sea frog. In one church, during the service, the priest even told the congregation about the stone bones left over from a gigantic beast that did not fit into Noah’s ark. Rumors fueled curiosity, and people crowded into the ravine every day.
In the confusion, a couple of bones were stolen, and Vedenyapin asked the police to send a security detail. It didn’t 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 articles about treacherous priests and where the butter and sugar had disappeared, a call appeared: “We kindly request those present not to interfere with the work and comply with the demands of those leading the excavations!”
When 30 cubic meters of rock were dumped into the dump, the lower jaw appeared - long, with crooked teeth. It became clear that the remains of a giant marine reptile were found in the ravine - mosasaurus. The jaw was outlined in a trench. It turned out to be a kind of table on which lay a rock-covered bone. They did not take it out for fear of breaking it, and they sent a telegram to the Academy of Sciences to send specialists.
Mosasaurus tooth from a private collection, Cretaceous layers of the Saratov region. Photo: Maxim Arkhangelsky
In early September, two preparators from the Russian Geological Committee arrived in Penza and, according to the newspaper, immediately “began work on exposing the mosasaurus and excavating it.” It was necessary to remove the bones before the slope melted due to rains. And the shooting range had been idle for half a month. In a couple of days, the find was cleared of the rock. 19 large teeth, flattened on the sides, 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. A plaster copy was then donated to the regional museum. As it turned out, the remains belonged to a giant who lived at the end of the era of dinosaurs - the Hoffmann mosasaurus (Mosasaurus hoffmanni), one of the last sea lizards. Mosasaurs were real colossuses.
But they were not the only ones who lived in the Central Russian Sea, which existed in the territory Central Russia in the Mesozoic era. During the Jurassic and Cretaceous periods of this era, many dynasties of lizards were replaced. 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 them are in the Volga region - a giant cemetery of sea giants.
The sea came to the eastern edge of Europe about 170 million years ago, in the middle of the Jurassic period. “The general rise in sea levels during the Mesozoic era gradually led to the fact that the eastern part of Europe found itself under water. Then it was not yet a sea, but rather a 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 islands of the Urals. Thousands of square kilometers went under water - from the future Orenburg steppes to Vologda and Naryan-Mar.
Penza Georgiasaurus (georgiasaurus pensensis) Georgiasaurs grew up to 4-5 meters in length. Judging by the size and proportions of the limbs, they were quite strong swimmers and lived in the open sea. These lizards ate mainly small fish and cephalopods, although they may not have disdained 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 shallows rose from the water, teeming with fry and shrimp. There was noise on the islands coniferous forests, dinosaurs roamed, and the water element was conquered by swimming lizards.
In the Jurassic period, 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 slabs of slate, like a giant stone book, are often covered with impressions and shells as thickly as this page is covered with letters. The bones of lizards were especially often found in the first third of the last century, when an energy famine came to the country and the Volga region switched to local fuel - oil shale. Like mushrooms after rain, grandiose underground labyrinths of mines have 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 miners to preserve the bones, but this has helped little. Director of the Paleontological Institute of the USSR Academy of Sciences, Academician Yuri Orlov, recalled how during an expedition he visited the workers at the mine and told them for a long time about the enormous value of ancient bones.
“Finds like yours serve as decoration for museums,” he said confidentially. To which the chief engineer replied: “Only stupid people go to museums...”
Clidastes. These lizards hunted 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 were still preserved, thanks to dedicated local historians. One of these enthusiasts was Konstantin Zhuravlev. In 1931, near his hometown of Pugachev in the Saratov region, oil shale began to be developed - first by opencast mining, then by mines.
Soon, broken bones, broken fish prints and shells appeared in the dumps. Zhuravlev began to frequently visit the mine, climbed onto the dumps and talked with the workers, explaining to them how important the fossils were. The miners promised to take a closer look at the rock and, if they come across something interesting, to notify the museum. Sometimes, in fact, they notified - but rarely and late. The local historian collected almost the entire collection himself.
Mostly he came across the remains of ichthyosaurs. Over the course of 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).
These were medium-sized lizards. They grew to three to four meters in length and, judging by the proportions of their bodies, were good swimmers, but probably preferred to hunt from ambush. At the moment of the throw, they may have developed a speed of up to 30-40 kilometers per hour - quite sufficient to keep up with small fish or cephalopods, their main prey.
One day a real giant escaped from Zhuravlev. At the end of the summer of 1932, he learned that miners, while digging a tunnel, for several days came across huge vertebrae of the lizard - they were called “carriages”. The miners did not attach any importance to this and threw everything away. Only one “stroller” survived, which was given to a 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, there are also skeletons of 14-meter fish lizards in the world.
To match these giants were Jurassic plesiosaurs. Their remains are much less common than the bones of ichthyosaurs, and usually in the form of fragments. One day Zhuravlev picked up a half-meter-long fragment of the lower jaw from a dump, from which fragments of 20-centimeter teeth were sticking out.
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 was apparently three meters high. A person would fit in it like in a bed. Most likely, the jaw belonged Liopleurodon russian(Liopleurodon rossicus) - one of the largest marine predators in the entire history of the Earth.
Lioprevrodon
“They grew up to 10-12 meters long, weighed 50 tons, but, judging by some bones, there were 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 oil shale mining.”
Soon after the end of the Great Patriotic War An expedition from the Paleontological Institute discovered mine dumps in Buinsk ( Chuvash Republic) and Ozinki ( Saratov region) fragments of the skulls of two Liopleurodons. Each fragment is the size of a child.
Probably, the large skeleton found in the early 1990s at a mine near Syzran also belonged to Liopleurodon. Cracking open the shale, the combine's bucket hit a huge block. The teeth scraped its surface with a grinding sound, and sparks rained down. The worker climbed out of the cabin and examined the obstacle - a large nodule from which black bones, as if charred, were sticking out. The miner called the engineer. The work was suspended and local historians were called in. They photographed the skeleton, but did not remove it, deciding that it would take a lot of time. The mine management supported them: the face stood idle for a day already. The find was lined with explosives and blown up...
New times
Liopleurodons lived at the very end of the Jurassic period, when the Central Russian Sea reached largest sizes. “Several million years later, in the Cretaceous period, the sea broke up into separate, often desalinated bays and then left, then returned for a short time. A stable basin remained only in the south, reaching the borders of the present Middle and Lower Volga regions, where a grandiose archipelago stretched: many islands with lagoons and sandbanks,” explains paleontologist, professor at Saratov University Evgeniy Pervushov.
By that time, sea lizards had undergone great changes. The ichthyosaurs that swarmed the Jurassic seas almost became extinct. Their last representatives belonged to two genera - platypterygium(Platypterygius) and sveltonectes. A year ago, the first Russian sveltonectes(Sveltonectes insolitus), found in the Ulyanovsk region, is a two-meter fish-eating lizard.
Platypterygium was larger. One of the largest fragments was found 30 years ago in the vicinity of the Saratov village of Nizhnyaya Bannovka. It was with difficulty that the narrow and long front part of the skull was pulled out from the high Volga cliff. Judging by its size, the lizard reached six meters in length. The bones turned out to be unusual. “Extensive depressions are visible on the frontal part of the skull, and a number of holes are visible on the lower jaw. Dolphins have similar structures, and they are associated with echolocation organs. Probably, the Volga lizard could also navigate in the water by sending high-frequency signals and catching 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 long-time competitors - 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 didn’t care - they spread across a variety of sea basins. In the Cretaceous period, long-necked lizards began to predominate among them. Last year, one of these giraffe lizards was described from Lower Cretaceous deposits - Abyssosaurus Natalia(Abyssosaurus nataliae). Its scattered remains were dug up in Chuvashia. This plesiosaur received its name - Abyssosaurus (“lizard from the abyss”) due to the structural features of its bones, which suggest that the seven-meter giant led a deep-sea lifestyle.
In the second half of the Cretaceous period, among plesiosaurs, 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 animals. 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 passing fish and belemnites (extinct cephalopods).
We have not yet found complete skeletons of elasmosaurs, but individual bones form large clusters: in some places in the Lower Volga region from one square meter you can collect a “harvest” of several teeth and half a dozen vertebrae the size of a fist.
Short-necked animals lived together 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 and puddles all around, and they could throw the stove at the change house and clean the dirt from the soles of their boots. One day, a worker, wiping his feet, noticed that strange lines formed a whole picture - the head of a lizard.
After some thought, he called the local museum. Local historians arrived at the quarry, cleared the slab and were amazed to see an almost complete imprint of the skull, spinal 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 fragile and crumbled, but the imprints remained. Based on them, a new, so far the only species of Russian polycotylides was described - the Penza Georgiasaurus pensensis.
Last year, paleontologists, thanks to a discovery by scientists at the Natural History Museum in Los Angeles, finally discovered that plesiosaurs were viviparous reptiles.
But it was not plesiosaurs that became the main marine predators of the end of the dinosaur era. The true masters of the seas were mosasaurs, whose lizard ancestors descended into the sea in the middle of the Cretaceous period. Perhaps their homeland was precisely the Volga region: 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 Saratov province They apparently dug up the complete skeleton of this lizard. But it was not scientists who found it, but peasants.
They broke out the blocks with bones and decided to sell them to a glue factory. Such factories were smoking all over the country. There, glue, soap and bone meal for fertilizer were made from the remains of cows, horses and goats. They also did not disdain fossil remains: a Ryazan bone factory once bought four skeletons of big-horned deer for processing. But only Saratov men thought of using a petrified lizard for soap...
By the end of the Cretaceous period, mosasaurs settled throughout the planet: their bones can now be found everywhere - in American deserts, in the fields of New Zealand, in the quarries of Scandinavia. One of the richest deposits was discovered in the Volgograd region, not far from the Polunin farmstead, right on the collective farm melon patch.
Among the cracked lumps of hot earth, near the watermelons, lie dozens of rounded teeth and vertebrae of mosasaurs. Among them, the huge teeth of the Hoffmann mosasaurs, similar to browned bananas, stand out especially - the same one, next to which almost all other Cretaceous lizards looked like dwarfs.
Khans and kings of the Mesozoic era
The Hoffmann mosasaurus could be considered the largest Russian lizard, if not for the strange finds that are occasionally found in the Volga region. Thus, 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 in size to whales and were the largest predators in the entire history of the Earth. Another time, near an abandoned shale mine, a vertebra the size of a bucket was found. 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, up to 20 meters long.
Unfortunately, scattered fragments are not always suitable for scientific description. It is only clear that the subsoil of the Volga region holds many mysteries and will present more than one surprise to paleontologists. The skeletons of the planet's largest sea lizards may also be found here.
National Geographic No. 4 2012.
It seemed that these toothy and big-eyed marine predators went extinct tens of millions of years ago, but there are reports that ichthyosaurs are still found in the seas and oceans. Although these ancient creatures are similar in many ways to dolphins, it is difficult to confuse them with them, because distinctive feature Ichthyosaurs have huge eyes.
Dolphin-like lizards-eyed
From the sea predatory dinosaurs We are most familiar with plesiosaurs, and this is not surprising, because the famous Nessie is classified precisely as this type of aquatic lizard. However, in the depths of the sea at one time there were other types of predatory reptiles, for example, ichthyosaurs, which inhabited the seas and oceans 175-70 million years ago. Ichthyosaurs, which look like dolphins, according to scientists, were once among the first dinosaurs to return to the water element.
Unlike the plesiosaur with its long neck, the head of the ichthyosaur, like that of fish, was integral with the body; it is not for nothing that the name of this reptile is translated as “fish lizard”. For the most part, ichthyosaurs were not large in size, their length was 3-5 meters. However, among them there were also giants, for example, in the Jurassic period some species reached a length of 16 meters, and in polar regions Canadian paleontologists have discovered the remains of an ichthyosaur about 23 meters long (!), which lived in the Late Triassic.
These were toothy creatures, and their teeth were replaced several times during their lives. It is especially worth stopping at the eyes of ichthyosaurs. These reptiles had very large eyes, reaching 20 cm in diameter in some species. According to scientists, this eye size suggests that ichthyosaurs hunted at night. The eyes were protected by a bone ring.
The skin of these lizards had neither scales nor horny plates; according to scientists, it was covered with mucus, which provided better gliding in the water. Although ichthyosaurs are very similar to dolphins, they had a fish-type spine that curved in a horizontal plane, so their tail, like ordinary fish, was located in a vertical plane.
What did ichthyosaurs eat? It was widely believed that they favored the extinct cephalopod belemnites, but a team of researchers led by Ben Kier from the South Australian Museum refuted this idea. Scientists have carefully examined the stomach contents of a fossilized ichthyosaur that lived 110 million years ago. It turned out that there were fish, small turtles and even a small bird in it. This study allowed us to refute the hypothesis that ichthyosaurs became extinct due to the disappearance of belemnites.
It is curious that these marine reptiles were viviparous; this feature is clearly proven by paleontological finds. Scientists have repeatedly found the fossilized remains of ichthyosaurs, in the belly of which there were skeletons of unborn cubs. Newborn ichthyosaurs were forced to immediately begin an independent life. According to scientists, as soon as they were born, they already knew how to swim perfectly and get their own food.
Mysterious “weevil whales”
Ichthyosaurs reached their greatest diversity in the Jurassic period, and became extinct at the end of the Cretaceous. Or maybe they didn’t become extinct? After all, there is the opinion of a number of scientists that the same ichthyosaurs were warm-blooded and could well adapt to changing conditions in the ocean. When these lizards that have survived to this day die or die, their remains sink to the bottom, scientists accordingly do not find them and consider ichthyosaurs extinct.
In the early 1980s, the sailor of the Soviet cargo ship A. B. Fedorov, while sailing in the Indian Ocean, observed unusual marine animals, according to his description, very similar to ichthyosaurs. An eyewitness recalled: “I saw a light brown back and a characteristic whale fountain, but... it was not a whale or a dolphin. I saw such an animal for the first and so far only time in my life. The fact that this is some kind of mutant is excluded. There were at least five of these long-faced, toothy “whales” with large saucer-like eyes. More precisely, the eyes were in the center of the saucers.”
If this observation was the only one, it could be assumed that the sailor was mistaken and mistook quite ordinary inhabitants of the ocean for unusual creatures. However, in the spring of 1978, two members of the crew of the fishing vessel V.F. Varivoda and V.I. Titov observed a very strange sea animal with a toothy mouth. Titov described it this way: “The steep, rounded back of the head rose above the water by about 1.5 meters; a white stripe stood out brightly on the upper jaw, which, gradually expanding, stretched from the end of the muzzle to the corner of the mouth and was bordered below by a narrow black stripe... In the profile of the head was cone-shaped. The height of the upper jaw at the level of the corner of the mouth was about one meter... The total length of the head was from one and a half to two meters.”
V.I. Titov told the senior researcher at the Cetacean Laboratory, Candidate of Biological Sciences A. Kuzmin, about the mysterious animal he had encountered. The scientist had known Titov for 10 years by that time, so he took his story seriously. It is curious that Titov told him that he had seen similar “weevil whales” in Indian Ocean repeatedly, and such animals usually kept in a small flock of 6-7 individuals, sometimes including cubs among them.
Kuzmin showed his acquaintance many photographs and drawings of various sea animals, but Titov never identified his “weevil.” But when an image of an ichthyosaur accidentally caught his eye, he said that it was very similar to the creatures he had met.
A very living fossil?
So, there are observations of trustworthy people who have seen unknown large marine animals that are very similar to ichthyosaurs that went extinct tens of millions of years ago. Why not assume that ichthyosaurs, which at one time were distributed almost everywhere in all seas and oceans, managed to survive to our time only by significantly reducing their habitat?
It should be noted that even Soviet scientists took the messages of Fedorov and Titov quite seriously; information about a meeting with a large marine animal unknown to science was published in 1979 in the journal “Knowledge is Power.” The skepticism of scientists in recent times, of course, has been greatly influenced by the discovery of lobe-finned fish, which were considered extinct long ago. If she managed to survive to this day, then why couldn’t the ichthyosaur do it?
French scientists concluded that ichthyosaurs were warm-blooded. This conclusion was made based on data on the content of the stable oxygen isotope 18 0 in the fossil remains of ichthyosaurs. It was possible to prove that the body temperature of marine reptiles was higher than the body temperature of fish that lived with them at the same time. This discovery by scientists suggests that ichthyosaurs could well have survived, especially since they did not feed on belemnites alone. It remains to be seen that more compelling evidence for the existence of these prehistoric animals will emerge. Fortunately, many sailors now have both cameras and video cameras, and we can well hope to see footage of a whole flock of big-eyed and toothy creatures from the Jurassic period frolicking in the waves.
Prepared by Andrey SIDORENKO
Marine reptiles
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 became 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 for life in water. This fact can only mean that some reptiles returned back to the sea, to their homeland, where the ancestors of dinosaurs - fish - appeared long ago. 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 to be a step backward from an evolutionary point of view simply on the grounds that Devonian fish came out of the sea onto land and developed into reptiles after passing through the amphibian stage. On the contrary, this position illustrates the principle according to which each actively developing group of organisms strives to occupy all varieties of the environment in which it can exist. In fact, the movement of reptiles into the sea is not very 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 method of movement in aquatic environment. Of course, reptiles continued to breathe air in the same way that a modern whale, a mammal, although similar in body shape to a fish, breathes air. Moreover, Mesozoic marine reptiles did not evolve from any one land reptile that decided to move 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 was to changing environmental conditions, as a result of which a vast space was created, abundant in food and suitable for settlement.
Extensive information has been obtained from the study of fossil remains contained in marine mudstones and chalk limestones; These fine clastic rocks preserve not only bones, but also imprints of skin and scales. With the exception of the smallest and most primitive species, most marine reptiles were predators and belonged to three main groups: thyosaurs, plesiosaurs and mosasaurs. Briefly characterizing them, we must first note that ichthyosaurs acquired an elongated shape similar to fish (Fig. 50) and were excellently adapted to fast swimming in pursuit of fish or cephalopods. These animals, reaching 9 meters in length, had bare skin, a dorsal fin and a 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 the fingers in these flippers were closely connected, and there were additional bones in them to increase strength. Big eyes Ichthyosaurs were adapted to see well in water. They even had one very significant improvement in the reproduction process. Being air-breathing animals that lived in seawater, they could not lay eggs. Therefore, ichthyosaurs developed a method of reproduction in which the embryo developed inside the mother’s body and, upon reaching maturity, was born alive. They became viviparous. This fact is established by the discovery of perfectly preserved remains of female ichthyosaurs with fully formed young inside their bodies, the number of young 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 different appearances, but in the course of evolution they acquired external similarities
The second group includes plesiosaurs, which, unlike the fish-like ichthyosaurs, retained the original body shape of reptiles, 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 same land reptile that gave rise to the ichthyosaurs. The legs of plesiosaurs turned into long fins, and the head, set on a long neck, was equipped with sharp teeth that closed and reliably held the most slippery fish. Such teeth prevented chewing; The plesiosaur swallowed its prey whole and then crushed it in its stomach using pebbles. The diet of plesiosaurs can be judged from the stomach contents of one of them, which apparently died before the stones in its stomach had time to properly crush the food it swallowed. It was found that the bones and fragments of shells contained in the stomach belonged to fish, flying reptiles and cephalopods, which were swallowed whole, along with the shell.
The third group of marine reptiles is called mosasaurs because they were first discovered near the Moselle River in northeastern France. They could be called “belated” because they appeared only in the Late Cretaceous, when ichthyosaurs had been populating 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 designed in such a way that they could open their mouths wide, like snakes.
A streamlined body as an adaptation to living conditions in an aquatic environment is found not only in ichthyosaurs and mosasaurs. The same can be seen in a number of animals that lived before and after the Mesozoic, and in the Mesozoic (Fig. 50).
Some of the largest creatures that have ever inhabited this world lived millions of years ago. Below are ten of the biggest, scariest sea monsters, who once prowled the oceans:
10. Shastasaurus
Ichthyosaurs were marine predators that looked like modern dolphins and could reach enormous sizes; they lived in Triassic about 200 million years ago.
Shastasaurus, the largest species of marine reptile ever found, was an ichthyosaur that could grow to more than 20 meters. It was much longer than most other predators. But one of the largest creatures to ever swim the sea was not exactly a fearsome predator; Shastasaurus fed by suction, and ate mainly fish.
9. Dakosaurus
Dacosaurus was first discovered in Germany, and with its strangely reptilian yet fish-like body, it was one of the main predators in the sea during the Jurassic period.
His fossil remains were found over a very wide area - they were found everywhere, from England to Russia to Argentina. Although it is usually compared to modern crocodiles, Dakosaurus could reach 5 meters in length. Its unique teeth led scientists to believe it was a top predator during its terrible reign.
8. Thalassomedon
Thalassomedon belonged to the Pliosaur group, and its name is translated from Greek as “Lord of the Sea” - and for good reason. Thalassomedons were huge predators, reaching up to 12 meters in length.
It had nearly 2 meter long flippers, allowing it to swim in the depths with deadly efficiency. Its reign as a predator lasted until the late Cretaceous period, until it finally came to an end when new, larger predators such as Mosasaurs appeared in the sea.
7. Nothosaurus
Nothosaurs, reaching a length of only 4 meters, were aggressive predators. They were armed with a mouthful of sharp, externally directed teeth, indicating that their diet consisted of squid and fish. It is believed that Nothosaurus were primarily ambush predators. They used their sleek, reptilian physique to sneak up on their prey and surprise it when attacking.
It is believed that Nothosaurus were relatives of pliosaurs, another type of deep sea predator. Evidence obtained from fossil remains suggests that they lived during the Triassic period about 200 million years ago.
6. Tylosaurus
Tylosaurus belonged to the Mosasaurus species. He was huge size, and reached more than 15 meters in length.
Tylosaurus was a meat eater with a very varied diet. In their stomachs, traces of fish, sharks, smaller mosasaurs, plesiosaurs, and even some flightless birds. They lived at the end of the Cretaceous period in a sea that spanned what is now North America, where they sat tightly at the top of the marine food chain for several million years.
5. Thalattoarchon Saurophagis
Only recently discovered, Thalattoarchon was the size of a school bus, reaching almost 9 meters in length. This is an early species of ichthyosaur that lived during the Triassic period, 244 million years ago. Due to the fact that they appeared shortly after the Permian extinction (the largest mass extinction on Earth, when scientists believe 95% marine flora and fauna were destroyed), its discovery gives scientists a new look at the rapid recovery of the ecosystem.
4. Tanystropheus
Although Tanystropheus was not strictly a marine animal, its diet consisted mainly of fish, and scientists believe that it spent most of its time in the water. Tanystropheus was a reptile that could reach 6 meters in length and is believed to have lived during the Triassic period about 215 million years ago.
3. Liopleurodon
Liopleurodon was a marine reptile that reached more than 6 meters in length. It primarily lived in the seas that covered Europe during the Jurassic period, and was one of the top predators of its time. Its jaws alone are believed to have reached more than 3 meters - this is approximately equal to the distance from floor to ceiling.
With such huge teeth, it is not difficult to understand why Liopleurodon dominated the food chain.
2. Mosasaurus
If Liopleurodon was huge, then Mosasaurus was colossal.
Evidence obtained from fossil remains suggests that Mosasaurus could reach up to 15 meters in length, making it one of the largest marine predators of the Cretaceous period. The Mosasaurus's head was similar to that of a crocodile, and was armed with hundreds of razor-sharp teeth that could kill even the most heavily armored opponents.
1. Megalodon
One of the largest predators in marine history and one of the largest sharks ever recorded, Megalodons were incredibly fearsome creatures.
Megalodons roamed the depths of the oceans for Cenozoic era, 28 - 1.5 million years ago, and were a much larger version of the great white shark, the most feared and powerful predator in the oceans today. But while the maximum length that modern great white sharks can reach is 6 meters, Megalodons could grow up to 20 meters in length, which means they were larger than a school bus!
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