Biography of the White Shark

The history of sharks: From the first ancestors to modern species, the history of sharks begins from those times when the only vertebral creatures on Earth were fish over time the gill arches of the ancient fish ossified, their jaws were formed, and teeth formed from scales covering gill records. So about four hundred million years ago, fish from prey turned into predators.

At this time, there were still no dinosaurs or pterodactyls on Earth, and the ancient ancestors of modern sharks have already plowed the world ocean. Then the dinosaurs left a deep mark in the history of the Earth, but for a long time they “sunk into oblivion”, and sharks, as before, continue to patrol the sea expanses. Sharks are the most advanced predators of planet Earth.

And the most mysterious. So many myths and legends are folded about them that no one will take them even just to count them. The origin of the sharks of paleontologists came to the conclusion that the first shark -like organisms arose about - millions of years ago, the most ancient artifacts belonging to the ancestors of sharks are dated about millions of years. This is fossil of fossils of teeth, belonging to a small creature no longer than thirty centimeters.

Why only teeth? Sharks, both modern and prehistoric, do not have a bone skeleton, it consists of cartilage in them. The cartilage, unlike bone, is practically not preserved in the fossil state, thus finding a petrified skeleton of a prehistoric shark is quite problematic. Finding even part of the skeleton of the ancient shark is a huge luck, each of the found has been studied by paleontologists thoroughly, but until now, none of the scientists can confidently say that the mystery of the origin of the sharks is completely disclosed.

The most ancient skeleton of the shark dates from about millions of years. This is the Devonian period. Devon is the fourth of the six geological periods of the Paleozoic era, which lasted from to million. At that time, almost the entire territory of North America and Europe was covered with water smoothness. Moreover, these were warm seas, which created the sea organisms excellent conditions for life, reproduction and development.

It is not surprising that it was during this period that a huge number of sharks appeared, starting from the smallest, less than a meter long and ending with monsters several meters long. Already during this period, the simplicity of the body of the shark’s body distinguishes it favorably from the clumsy shells outdated or plate -skinned the modern name of the fish. The advantage of sharks is growing, they have the best hydrodynamic qualities, which means they can quickly develop speed, overtake prey faster, which, in turn, helps sharks not to experience a shortage in the stern.

But that's not all. In the same period, sharks appear that have a “conveyor” tooth change mechanism. Since the teeth are the ideal weapon of sharks, their presence and condition play a huge role in the quality of the life of predators. Yes, the loss of one or two teeth is not a tragedy, but if it is lost or 50 percent of their number? Types of ancient sharks are most famous for the world by several ancient representatives of the shark kingdom.

Let's talk about them in more detail. Claudoslachia - the first shark, the most first sharks, paleontologists call pantoselachies, the petrified remains of the scales of which are dated to the Devonian period of the Paleozoic era. A little later, the teeth of this prehistoric predator were found. The petrified remnants of the shark were discovered in the deposits of Slates of the state of Ohio.

According to the paleontologist from the United States, B. Sheffer of Claudosellachia made up a special group of predatory fish that occurred from even more ancient predators - placerm or plately fish, they were previously mistakenly called shells. Their “shell” consisted of separate plates covered with skin, and not with bone shields, as was thought before. The most outstanding paleontology scientists consider the find of the imprint of the carcass of the first shark that lived on the ground hundreds of millions of years ago: in addition to the general outlines and skeleton of predators, prints of its muscles and even kidneys are visible.

Thanks to this find, paleontologists found that the length of the pantoslachia was about two meters, that is, it was far from the largest predators of the Devonian period. But the shape of the shark’s body, reminiscent of a torpedo, allowed her to move quickly and, therefore, quickly catch up with a potential victim. Therefore, these ancient monsters did not have a shortage.

After a more thorough study by the paleontologists of the structure of the fins of this shark, they came to the conclusion that the storehouse in speed was still inferior to modern representatives of sea predators. There are several more significant differences between the pantoslachia from modern sharks: the modern muzzle predators are more acute than the ancient representatives of the cartilage in them is shorter and rounder, and the mouth is on the lower side of the head.

In Kleadoslachia, he was much higher. In ancient sharks, the jaw was attached to the skull both in front and behind, in modern ones - only from behind. Therefore, our contemporaries can open their mouth wide, and its ancient ancestors could not do this.The pantoslachia in each fin on the back had a kind of spike, the modern shark lost it. Ancient predators were practically devoid of scales.

But the body of the modern shark is covered with a dense layer of the so -called plateau scales. Each of the scales is a kind of rhomboid -shaped plate, which seems to germinate through the skin and goes outside, and all scales are oriented towards the tail. This prehistoric predator is also known as the Shark Ginsa. She inhabited the seas and oceans of the Earth in the middle and end of the Cretaceous period from about one hundred to eighty million years ago.

The length of the baptoxsorine was up to eight meters, and the weight varied from five hundred to nine hundred kilograms, that is, in size it was comparable with such modern sea predators as a large white shark. She had sharp and fairly long teeth, more like knives. Therefore, it was not difficult for her not only to get a huge fish for lunch, but also to deal with the cub of the mosazar of the naval lizard or the smaller shark Squarerax.

Even in the nearest suburbs, if you wish, you can try to find the remnants of ancient sharks, including Beretoxsin. To do this, it will be enough to sign up for an individual or group with a number of no more than four people a weekend tour, which is held in the Sergiev Posad district near Varavino. The find of fossilized remnants of various organisms that inhabited the Earth hundreds of millions of years ago is guaranteed.

Skalikorax is another shark of the Cretaceous period. Squarecracles were smaller than the cretoxsin. Their length varied from two to five meters, so they and especially their cubs often became the prey of these larger relatives. Outwardly, they resembled such modern representatives of a family shark as a gray shark, and in the form and structure of the teeth - on another modern predator - a tiger shark.

Cardabiodon is a large shark that inhabited the waters of the World Ocean during the late Cretaceous period of the Senomanian age. It lasted a little less than seven million years and lasted from 93 to millions of years ago. The average length of cardabiodons was about five and a half meters, but some specimens reached a length of up to seven meters. There were also smaller sizes of individuals, for example, in the year the remnants of cardabiodon were described about three meters long.

Helicoprion is one of the most fantastic and unusual marine creatures that have ever inhabited the Earth. Translated from Greek helikoprion means "spiral saw." Why such a strange name? This prehistoric shark had the so -called reel teeth located in the form of a spiral or circle. Paleontologists have not yet come to a consensus - how they “worked”: at first they stated that their teeth rotated like a circular saw, cutting the prey into parts; Then it was argued that the teeth during the hunt turned into a kind of chain, clinging to the victim and tearing it into pieces; Currently, the assumptions have been put forward that with the help of a dental spiral, helikoprions sawed the shells of the cephalopods of ammonites, etc.

But so far is so little known about this monster, and this information is so fragmentary that it is not yet possible to draw up any unambiguous expert opinion. All that was found is the phossil of the jaws of a marine creature and its mysterious tooth spiral.

Of course, it is not yet possible for the residues found in sufficient detail to describe in sufficient detail. During the search for fossils in Klyuchikov’s career, the tourists often find shark teeth. Maybe you are lucky and you can bring even the Gelicoprion teeth home. Megalodon and finally - megalodon. The largest of the ever-lived sharks, some specimens reached a length of almost twenty-five meters and weighed up to ninety tons.

Megalodons inhabited the world ocean recently-from twenty-six to just two million years ago. Almost yesterday. Of course, on average, its size was somewhat more modest: from fifteen to twenty meters in length and from sixty to eighty tons weighing, but, you see, to meet such a “average” monster in its path, probably, no one would have wished. Imagine - if Megalodon wide open his mouth, then a tall man could easily fit there, and the monsters' teeth reached a length of up to twenty centimeters.

Their prey was mainly whales, including the largest - Leviathana. The extinction of the ancient sharks for a long period - from the first pantoslachia, who lived millions of years ago to the largest sharks of all time of megalodones, some species of predators replaced other, more developed and perfect ones. About millions of years ago, during the so -called mass Perm extinction, a huge number of species of both ground and marine inhabitants, including a large number of sharks, disappeared.A little earlier, about millions of years ago, the pantoslachy disappeared, then helikoprions, Xenakants took their place, the outer structure of the body of which was slightly reminiscent of their distant ancestors of the pantoselachia.

Xenakantovs set a kind of record of the duration of the existence of the species, but in the trias period they also died out. They were replaced by Squarecracles and Cardabiodons, who could not survive Mel-Paleogene extinction one of the five most massive extinctions, occurred on the border of the Cretaceous and Paleogene periods. Around the same time, baptoxyrines disappeared.

Well, perhaps one of the most dramatic stories about the life and the disappearance of the most “young” of the ancient sharks - megalodons. They died out about two million years ago. Yes, the opinions of paleontologists were divided: some believe that these monsters disappeared about 2, 6 million years ago, others say that almost a million years later. Be that as it may, they were gone.

The extinction of megalodons was facilitated by several factors at once, the main of which was the global climate change. And the climate, in turn, has changed dramatically due to global changes in the earth's crust. In the era of Pliocene, which lasted a little less than three million years from 5.3 to 2. The Atlantic and Pacific Oceans finally separated from each other.

The previously existing direction of the currents of the oceans has changed, the intake of the huge warm masses of water to the northern regions of the Earth, and especially to the Arctic, ceased. The northern hemisphere of the Earth gradually but noticeably cooled. The whales and their cubs, which made up the main part of the diet of megalodones, began to migrate massively north, closer to cold sea waters, and the megalodones lost the feed base.

Mass hunger provoked rampant cannibalism, as a result of which a huge number of cubs and young animals did not live to the childbearing period and did not have time to produce offspring. The population of megalodones began to decline rapidly. The second reason for the mass extinction of these marine monsters is the appearance of wanderers, the subordinate of toothy whales, the family of oceanic dolphins.