Why did the dinosaurs disappear? Why did dinosaurs become extinct? Location and directions of continental drift during the Cretaceous period
About 66 million years ago, at the boundary of the Cretaceous and Paleogene periods, one of the five “great mass extinctions” known to science occurred, during which 80% of living creatures living on Earth died. The scale is amazing: almost all types of dinosaurs disappeared almost instantly, and the surviving animals underwent radical changes. However, scientists are still at a loss as to what caused this. There are dozens of theories explaining the extinction of dinosaurs, but none of them can be called 100% reliable. Let's find out about the 10 most popular versions in scientific circles.
10. Asteroid
One of the well-known theories is that the extinction of dinosaurs occurred due to the collision of the Earth with a huge asteroidOne of the most famous theories is that the extinction of dinosaurs occurred due to the collision of the Earth with a huge asteroid. Scientists have recorded incredibly high levels of iridium in sedimentary rocks corresponding to the Cretaceous-Paleogene period. Iridium is rarely found in the earth's crust, but is one of the main minerals in asteroids. There was only one problem: if such a gigantic cosmic body fell to Earth, it means there must be a crater somewhere. And it was found in 1990 near the Yucatan Peninsula (Mexico). The crater was named Chicxulub, its diameter is 180 kilometers, and the original depth, according to scientists, reached 18-20 kilometers. It is believed that it was formed after a collision with an asteroid with a diameter of about 10 kilometers. The impact energy was equal to 100 teratons in TNT equivalent (the most powerful thermonuclear device in history had a power of only 0.00005 teratons).
It is believed that the impact caused a devastating tsunami 100 meters high that penetrated deep into the continents. A shock wave also passed across the surface of the planet, and high temperatures led to forest fires around the world. A huge amount of soot was released into the atmosphere. The concentration of carbon monoxide in the air has increased hundreds of times. The surface of the Earth was closed from the direct rays of the Sun for many years by soot and dust clouds. Due to the lack of light, photosynthesis in plants slowed down significantly, which led to a decrease in oxygen content in the atmosphere. And by the time the clouds cleared, all the dinosaurs had already disappeared.
9. Global Firestorm
One theory suggests that after the asteroid hit the Earth, a real firestorm began that engulfed the entire planet. While most scientists agree that the Earth collided with an asteroid, they cannot agree on what exactly caused the extinction. One theory suggests that after the impact, a real firestorm began that engulfed the entire planet. The point is that during the collision, the smallest particles of rock were thrown high up. Gradually they formed grains of sand that began to fall into the atmosphere. There they became hot from friction with air, the temperature reached 1500°C. The sky turned bright red, and the entire planet was drowned in flames from fires spreading across the entire land. The researcher who developed this theory compared what was happening then with the consequences of dropping megaton bombs on every 7 square kilometers of the Earth's surface. Only animals that managed to hide in holes or under water had a chance of surviving the fiery tsunami.
8. The most powerful hurricanes
According to scientists from the Massachusetts Institute of Technology, a powerful hurricane could have caused the extinction of dinosaurs. Scientists from the Massachusetts Institute of Technology were able to simulate on a computer another scenario for the extinction of dinosaurs. In their opinion, the cause could have been a powerful hurricane. Theoretically, it was caused by the heating of a large area of water in the ocean (about 100 square kilometers) to a temperature of +50°C after a meteorite impact. Under such conditions, hurricanes would arise whose speed reached 1,100 kilometers per hour. For comparison: the most powerful hurricane in history is dated October 12, 1979. The wind speed then reached 350 kilometers per hour - only 30% of the above number.
Dinosaurs could still survive powerful hurricanes, but the fatal circumstance for them was that the wind rose to a height of up to 75 kilometers. Soon the ozone layer was destroyed, and the deadly solar radiation literally incinerated almost all life on the planet. Its restoration took several decades.
7. Gradual extinction due to competition from mammals
Mammals turned out to be more adapted to life; it was easier for them to find food and tolerate environmental changes Less dramatic is the theory that claims that dinosaurs did not die out instantly, but gradually, over several million years. The likely reason was fierce competition with mammals. The latter turned out to be more adapted to life; it was easier for them to find food and endure environmental changes.
The main difference between mammals and fossil lizards is the method of reproduction. Cold-blooded dinosaurs were known to lay eggs. Mammals gave birth to live young and then nursed them. Newborn dinosaurs were small, so for growth and development they needed a colossal amount of food, which became increasingly difficult to obtain. Finally, mammals carried children in the womb, while lizard eggs were vulnerable to predators who loved to feast on them. Everything is natural: a less developed and adapted to external conditions form of life gave way to a more advanced one.
6. Continental drift
Initially, all the continents made up a single giant continent called Pangea Dinosaurs, according to scientists, lived in the Mesozoic era (248-65 million years ago). The Mesozoic, in turn, is divided into the Triassic, Jurassic and Cretaceous periods. Initially, all the continents made up a single giant continent called Pangea. During the Jurassic period, Pangea gradually “broke” in half, and land parts began to move away from each other. By the time of the extinction of the dinosaurs, the continents had moved even further apart. The contours of the continents began to resemble modern ones.
Continental drift could have caused the extinction of dinosaurs, because their habitats changed dramatically, as did climatic conditions. The vegetation has changed, and it has become more difficult for herbivorous lizards to get food. With their numbers declining, hard times also came for the carnivorous dinosaurs.
5. Changes in sea level
Each period of mass extinction coincides with times of dramatic changes in global sea levels There have been 5 mass extinctions in Earth's history. Professor Madison from the University of Wisconsin believes that sea level changes were their “main culprit.” The earth was formed 4.5 billion years ago, but liquid water appeared on it much later. Interestingly, each period of mass extinction coincides with times of dramatic changes in global sea levels. New land areas emerged from under the water, while the usual habitats of animals were flooded. Accordingly, the vegetation and climate of these territories also changed. The lizards were unable to adapt to such drastic changes.
4. Diseases
Many dangerous infections began to appear around the time of the extinction of the dinosaurs. While examining the remains of mosquitoes and ticks, forever stuck in amber, Dr. George Poinar from the University of Oregon unexpectedly made an important discovery: it turns out that many dangerous infections began to appear around the time of the extinction of the dinosaurs. Perhaps the mighty dinosaurs disappeared from the face of the Earth due to a plague epidemic.
This disease would be devastating for them. The fact is that dinosaurs did not have a developed immune system, and they reproduced quite slowly. Infected individuals would quickly infect all their relatives with a fatal disease. Mammals were able to survive due to a more developed immune system.
3. Comet
Comets consist mainly of ice, dust, rocks, organic compounds, they are smaller in size, so they develop high speed According to a theory presented to the world in 1980, the death of the dinosaurs was caused by a comet hitting the Earth. This cosmic body consists mainly of ice, dust, rocks, and organic compounds, while asteroids are made only of stone and metal. Comets are also smaller, so they can reach higher speeds.
Critics disagree: in their opinion, the comet could not have been so large that its collision would have formed the Chicxulub crater. However, computer modeling showed them to be wrong. If the comet was moving at great speed, a crater of similar diameter could still form. Interestingly, in this situation, many times more dust and debris would rise into the atmosphere than during a collision with an asteroid.
2. Vulcan
For millennia, the Earth was surrounded by a continuous layer of dense clouds with a high sulfur content, which did not allow sunlight to pass through. Another theory says that the extinction of lizards was caused by the eruption of volcanoes belonging to the Deccan Traps (one of the largest volcanic formations on the planet). This area is located on the territory of modern India. During an eruption, sulfur would be released into the air for 10 thousand years. And the total volume of gases and dust entering the atmosphere was 10 times greater than in the case of a collision with an asteroid. For millennia, the Earth was surrounded by a continuous layer of dense clouds with a high sulfur content, which did not allow sunlight to pass through. The result was the oxidation of water in the world's oceans (accompanied by the death of the vast majority of its inhabitants) and sharp warming caused by the greenhouse effect.
This theory received further confirmation in 2009. Then, undersea oil drilling off the coast of India discovered massive eons of ancient solidified lava filled with sediment. The lava contained fossils dating back to the period of extinction of the dinosaurs.
1.Combination of different reasons
Dinosaurs that survived natural disasters may have disappeared a little later due to disease or climate change Many of the events listed above could have occurred almost simultaneously - that is, in a relatively small period of time on the scale of the epochs of the Earth's existence. Researchers debate what exactly led to the death of dinosaurs, but few deny this fact. For example, there is evidence that the collision of an asteroid or comet with our planet and powerful volcanic eruptions occurred at approximately the same time. Moreover, the fall of a celestial body to Earth could trigger the start of fires on all land areas.
The dinosaurs that miraculously survived these catastrophes could have disappeared a little later due to disease or climate change. Competition from mammals may also have played a big role. This version seems to be the most likely: most likely, the dinosaurs were simply very unlucky. They might have survived each cataclysm separately, but not all at once.
Svetlana Galitskaya
Children's project “Why dinosaurs became extinct”
Text presentation by the student, accompaniment of the presentation, independent experimentation on topic: "Why did dinosaurs become extinct??"
Section: "My first educational and research project»
(natural science direction)
Yudin Danil,
MADO TsRR-d/s No. 16 "Cockerel"
Tbilisi district,
Tbilisskaya village
Scientific supervisors:
Galitskaya Svetlana Petrovna,
senior teacher,
Skryabina Irina Georgievna,
teacher
MADO TsRR-d/s No. 16 "Cockerel"
Tbilisskaya village
« Why did dinosaurs become extinct?»
Danil Yudin
MADOOU TsRR – d/s No. 16 "Cockerel"
annotation
My parents instilled in me a love of learning new and interesting things in the world around me. What I like most is listening to my mother read, studying and looking at illustrations, watching TV shows and films on the topic « Dinosaurs» .
I asked my parents a question:
- Why did dinosaurs go extinct?, but the frogs, snakes, lizards and turtles that lived with them did not. It would be funny if Diplodocus looked into our window now, what would we do then?
Hypothesis: reason for disappearance dinosaurs- these are climatic changes in the surrounding world, to which dinosaurs couldn't adapt.
Target: explore possible causes of extinction dinosaurs, choose one that is most suitable.
Object of study: dinosaurs.
Tasks:
1. Structural features dinosaurs.
2. Learn extinction hypotheses dinosaurs.
3. Conduct a survey among children in your group, preschool teachers, and parents « Why did dinosaurs become extinct??»
4. Find the answer to your question « Why did dinosaurs become extinct??»
A long time ago…
A long time ago, our planet Earth was just a ball of fire, its surface covered with volcanoes and deserts. Under such conditions, life on the planet was impossible.
The first signs of life appeared in the ocean 3 billion years ago - these were bacteria and algae, then animals like worms and jellyfish appeared, then sea sponges, mollusks with hard shells and the first fish. Plants developed on land - moss, ferns, and the first insects appeared.
250 million years ago reptiles appeared - dinosaurs, which translated means "terrible lizard".
Fossils…
Scientists learned about the existence of ancient animals from fossils remains: after death torso dinosaur covered with sand by the wind or filled with water and mud, for example, during a landslide or earthquake. Over millions of years, the sand hardened and turned the bones into minerals as hard as rocks. Paleontologists - seekers, very carefully dug up the found remains, and then studied and collected from them entire skeletons of various dinosaurs. Searchers carried out excavations in different countries planets: in Germany, South Africa, China, Mexico, India.
What were they like...
To this day, more than a thousand species of reptiles have been studied. Dinosaurs unusual and very various:
Some of them were no larger than a chicken, while others weighed as much as 20 elephants;
Some are herbivores, while others are predators;
Some knew how to swim perfectly, while others could fly;
Some were toothy and had more than a thousand teeth in their mouths, some chewed vegetation with only two teeth.
Limbs dinosaurs were located directly under the body to make it easier to move without swaying from side to side.
Some were able to move with large leaps on their hind limbs, while their front limbs were very short.
Their bodies were covered with scaly and sealed skin.
They laid eggs protected by a strong shell, and some knew how to build nests.
What actually happened...
65 million years ago dinosaurs have simply disappeared from our planet. To explain this, scientists from many countries have studied and are now studying the reasons for their disappearance; history knows of assumptions about worldwide disasters:
The first is the hypothesis of W. Alvarez about the collision of planet Earth with a giant comet. The fall should have left huge craters, but scientists never discovered them.
The second is about an asteroid falling into the ocean, then died out would have been all the inhabitants of the ocean, but this did not happen.
The third is about the explosion of a distant star similar to the Sun, but astronomers have not found traces of such a star in the solar system.
The fourth is the hypothesis of J. Cove, about a volcanic eruption, but there were not volcanoes all over the earth.
Not one of the hypotheses has ever been proven by scientists.
Conclusion…
Summarize, dinosaurs died gradually due to several events - a volcanic eruption, an earthquake, and a comet fall, all of which affected the Earth's climate. After this, the plants began to change, the herbivores had nothing to eat, they began to die, and after them, having no food for themselves, predators began to die.
Life on Earth is designed in such a way that some animals die out, while others appear again. This suggests that wildlife and the surrounding world are closely related.
Giraffe - brachiosaurus,
Rhinoceros - Triceratops,
A bat is a flying lizard,
Crocodile – geosaurus and others.
- I want to remind everyone:
Let's protect nature, preschoolers!
We must not forget about her for a minute.
After all, birds, animals, fields and rivers,
This is all for us forever!
« Why did dinosaurs become extinct?»
Danil Yudin
MADOOU TsRR – d/s No. 16 "Cockerel"
Educational and research project
Educational Job: "What is a volcano?"
Goal and tasks: introduce the legend of the origin of the name "Volcano". Look at illustrations depicting volcanic eruptions, discuss how the eruption affects the surrounding nature and wildlife. To promote the development of skills to independently express one’s point of view and reason.
I spit fire and lava, This is a mountain,
I am a dangerous giant, There is a hole at the top,
I am famous for my evil fame, It’s hot inside!
What's my name? Sometimes it releases lava
(Volcano) There's no way to control her
What do you think a volcano is?
A mountain with a hole at the top through which magma pours out, smoke rises and stones fly. A volcano is a fire-breathing mountain.
What does the mountain look like?
On a cone, on a triangle.
What does a volcano erupt?
Hot lava pours out of a volcano. Gas, ash, and hot stones are released into the atmosphere.
"About the ancient god Vulcan".
“There lived a god named Vulcan. And he liked blacksmithing case: stand at the anvil, hit the iron with a heavy hammer, fan the fire in the forge. He built himself a forge inside a tall mountain. And the mountain stood right in the middle of the sea. When Vulcan worked with his hammer, the mountain trembled from top to bottom, and the roar and roar echoed far around. From the hole at the top of the mountain, hot stones, fire and ash flew with a deafening roar. “The volcano is working!”– people said with fear, and went to live away from this place.
Since then, people began to call all fire-breathing mountains volcanoes.”
Research: "Experience "Eruption".
Goal and tasks: to cultivate interest in cognitive and research activities, strong-willed qualities - perseverance, determination, independence. Acquaintance with a natural phenomenon - a volcanic eruption. Expand the prospects for the development of search and cognitive activity by including the child in thinking, modeling and transformative actions.
Material:
1. On a tray - a jar of baking soda, a jar of food grade citric acid, a jar of red gouache, a jar of water mixed with soap. "Test", teaspoon, napkin.
2. Layout "Habitat dinosaurs» - plastic trees and figures dinosaurs, a volcano mountain with a crater, made of construction foam and painted with gouache.
Progress of the experiment:
1. Place one teaspoon of baking soda into the crater of the volcano.
2. Add one teaspoon of food grade citric acid.
3. Mix carefully.
4. Add a little red gouache.
5. Carefully pour in a teaspoon of water mixed with a soap solution - 3-4 tablespoons.
6. Observe the seething - the eruption of lava from the crater of a volcano.
Questioning.
Children from the preparatory group were asked to answer the question « Why did dinosaurs become extinct?» :
Disasters:
1. Asteroid impact.
2. Collision with a comet.
3. Explosion of a new star in the solar system.
4. Volcanic eruption.
Lack of food.
Diseases dinosaurs.
Changing of the climate:
1. Ocean cooling.
2. Changes in seasonal air temperature.
3. Increased icing of the North and South Poles.
Bibliography.
1. « Dinosaurs» Joachim Oppermann, translation from German by V. F. Polezhaeva, 1994. Artist Manfred Gorbeck, editor A. V. Gura. typesetting and films of the Russian text were made by the publishing house "Word", 1993.
2. Collection cards "In the World of Wildlife", publisher LLC International Masters Publishers, 2011-2012.
3. N. N. Malofeeva Encyclopedia of preschoolers - M.: ZAO "Rosman-Press", 2008. – 200 p., 2006.
4. "Who? Where? Why?» Illustrated encyclopedia for little ones why check/ translation from English by V. V. Stepanova. – M.: AST: Astrel, 2010. – 173, p.: illustrations LLC "Publishing house Astrel", 2009.
5. A fun encyclopedia. Dinosaurs [Text]/Claude Bogaer; translation from French by P. Buntman; [artist G. Regalado]. – M.: Labyrinth Press, 2012.
6. Matthews Rupert "Atlas dinosaurs» /Translation from English by V.V. Naidenov. – Smolensk: Rusich, 2002. – 64 p.: illustrations.
7. Rublev S. “New atlas of animals for children. – Rostov n/d.: Vladis: M.: RIPOL classic, 2009.-48p.
8. "Animal Atlas"/Translation from French c. V. Naydenova. – Smolensk: Rusich, 2011.-48p. Computer layout: E. Mikhalkina. Text: L. Cambournak.
9.Larousse "My first encyclopedia", edition in Russian by Sergey Dmitriev, translation from French by Natalia Speranskaya, 1994, edition "Perseus", "Veche", AST, 1994.
10. Encyclopedia "Living World" Leslie Colvin and Emma Spear. Translation from English by G. I. Rozhkova. Publishing House LLC "ROSMAN-PRESS", 2001.
11. Everything about everything. Ginny Johnson "Ancestors dinosaurs» /translation from English by A. Blaze; design by I. Salnikova; illustrations by N. Hussain. – M.: "Premiere", "Astrel", AST, 2000. – 40 p.
12. Discs VVS collection Vol.2 LLC "Media Alliance" 420107 Kazan, st. Petersburgskaya, 496, 2012.
13. www.dinosaur.ru – website about Dinosaurs.
14. http://ru.wikipedia.org – Wikipedia about Dinosaurs.
15. Bondarenko T. M. “Environmental activities for children 6-7 years old”.
In the mid-Upper Cretaceous period, 80 million years ago, there were hundreds of species of dinosaurs belonging to 14 families; Of these, two families were carnivorous, the rest ate plants.
All of them, except for representatives of one small family, were real giants and weighed over 2-3 tons.
Dinosaur extinction
Then it began to gradually decrease. During the last five million years of the Cretaceous period, this process accelerates, with herbivores disappearing faster than carnivores. Finally, 65 million years ago, the giant reptiles completely disappeared.
What caused this gradual decline and final extinction?
Many paleontologists believe that climate change was the immediate cause. Dinosaurs needed warmth. Their evolution took place in climatic conditions extremely different from the present ones.
The average annual temperature on Earth was higher, with northern regions such as Alaska having a nearly tropical climate, and throughout the year the temperature was almost even, without the sharp differences between seasons as in modern times.
About eighty million years ago, when dinosaurs began to disappear from the face of the Earth, temperatures around the world began to gradually decrease, and besides, the difference between its extreme annual values became much greater.
However, even at 50° north latitude, many fossil remains of dinosaurs from the end of the Cretaceous period were found, so, apparently, even at the time when they began to die out, there were many areas on our planet with fairly high and stable temperatures.
Basic extinction hypothesis
Many other hypotheses have been put forward to explain the reasons for the extinction of dinosaurs. But one fact remained almost completely unnoticed: the extinction of dinosaurs coincided with the appearance and spread of angiosperms. As already said, the giant reptiles were mainly herbivores, and the emergence of a new class of plants could have a detrimental effect on them.
As already noted, almost all dinosaurs were large animals. Firstly, this means that their reproduction, and, consequently, adaptation to changing environmental conditions was slow.
Secondly, they needed a lot of food. Calculations show that a five-ton dinosaur would have consumed about 200 kg of grass every day, and therefore needed annual grazing space of about 20 square kilometers.
It is clear that with such an appetite, any changes in the chemical composition of food plants could not but affect the giants that fed on them.
During the course of evolution, there have been many changes in the diversity and complexity of compounds synthesized by plants. Such changes have made it possible for new plant families to successfully compete with old ones in a changing ecosystem.
Tannins and alkaloids
What harmful substances, absent in lower and gymnosperm plants, appeared in higher, flowering plants?
In the process of evolution, many plants have developed the ability to synthesize protective compounds - tannins and alkaloids.
These bitter or toxic substances should repel herbivores and protect plants from being eaten.
Tannins have an astringent taste, like unripe apples, which contain these compounds in high concentrations.
They interfere with the digestion of proteins and inhibit the activity of enzymes, and their excess causes liver damage.
Alkaloids are bitter compounds; they have a much broader physiological effect. Some, such as strychnine, are very poisonous.
Others, such as morphine, exhibit psychotropic effects. Still others can have a harmful effect on reproduction and heredity.
There are almost no alkaloids in non-flowering plants; tannins are rarely found in them. But both of these classes of protective compounds are widespread in higher plants.
Given the huge amounts of food the dinosaur absorbed, it was unlikely that it could choose, like modern herbivorous mammals, only non-poisonous plants, and it most likely could not sense alkaloids in small doses.
Obviously, the lethal dose for a dinosaur was 40-50 g of alkaloids, and such an amount could easily have accumulated unnoticed in two hundred kilograms of the daily diet.
Some findings show that dinosaurs experienced an increased incidence of physiological disorders towards the end of their reign. This is evidenced by the increase in the size of the hypothalamus, and several fossil dinosaurs were found in a crouched position, suggesting alkaloid poisoning.
A more significant fact was also reported: a decrease in the thickness of the shells of dinosaur eggs. This is reminiscent of the effect of DDT on the eggshells of modern birds (the poison prevents the synthesis of the calcareous egg shell).
The decline in the number of herbivores was followed by a decline in carnivorous reptiles, as their peaceful relatives formed their main diet. Thus, it can be assumed that dinosaurs died as a result of “chemical aggression” of angiosperms.
By the end of the Cretaceous period, the fauna of the land had reached great diversity, and its representatives were perfectly adapted to life in the even and favorable climate of this era. However, disaster was just around the corner.
Based on the fossilized remains of two dinosaurs, the artist reconstructed a picture of a deadly fight between a small predatory Velociraptor and a shell-covered Protoceratops.
Typical herbivores of that time were also hadrosaurs, or duck-billed dinosaurs - bipedal reptiles ranging in size from medium to giant, which, if necessary, could move on four limbs. They got their name because of their wide, flat, toothless beaks, which in appearance resemble the beaks of modern ducks. Functionally, however, their beaks were designed to bite off large plant shoots. On the upper and lower jaws of gasdrosaurs, behind the beak, there were about 2 thousand teeth in several rows, well adapted for grinding tough plant food.
As large bipedal herbivores, hadrosaurs such as Edmontosaurus replaced the initially even more successful iguanodons in the Middle and Late Cretaceous.
Diversity of predators
In the Late Cretaceous period (approximately from 75 to 65 million years ago), the predator community also acquired a rather complex structure. Previously, theropods were divided only by size: small, medium and large. With a few exceptions, all theropods of the Jurassic period were similar to each other, while in the late Cretaceous the anatomical structure of carnivores became much more diverse.
There were many species of dromoesaurs of varying shapes and sizes. They probably knew how to camouflage themselves well in the forests of the Cretaceous period. Long legs and prehensile forelimbs with large curved claws clearly indicate their predatory nature.
At the lower end of the predator size scale at the time were the dromaeosaurids (literally, “running lizards”). This group included several species of dinosaurs, from small turkey-sized dromaeosaurs to the 6-meter-long Utahraptor. Dromaeosaurs were "highly specialized" predators. Their distinguishing feature is the large and extremely sharp claws of the second toes. To avoid blunting the ground when moving, these fingers were always straightened. A long tail with a large number of bone rods along almost its entire length helped maintain balance while running.
They caused fear
These fearsome animals were stalking predators. Having caught up with the prey, they grabbed it with their long forelimbs, inflicting fatal wounds with the “dagger” claws of the second toe. Dromaeosaurs gained ominous fame thanks to the film “Jurassic Park”, where Deinonychus (4.5 m in length) was called Velociraptor (which in reality was no larger than a large Great Dane) for greater effect. Additionally, Deinonychus is a North American form, and Velosirashor remains have been found in Mongolia.Dromaeosaurs occupied an ecological niche similar to cheetahs in the ecosystems of modern Africa. It is believed (although not proven) that they hunted in packs. Their prey likely included small hypsilophodonts and thescelosaurs, as well as hadrosaurs and other juvenile reptiles of larger species. Predators in the middle of the scale, such as Chilantaisaurus from the family Allosaurus, most likely hunted ceratopsians and medium-sized hadrosaurs. The largest land predators of this era (and all others, including our time) were tyrannosaurids.
In the Late Cretaceous period, tyrannosaurids included many different species. For example, the skull of the “small” (about 7 m in length7) tyrannosaurid Alioramus from Mongolia was long and low, more reminiscent of a crocodile skull, while the most famous representative of this family, the tyrannosaurus rex (Tyrannosaurus rex), had a high, massive skull. The “predatory specialization” of the tyrannosaurus took a special path: the forelimbs of this 12-meter monster were reduced so much that they did not even reach its lower jaw. Their function is still a matter of speculation, but it is clear that they were not used to capture prey. For this purpose, the beast served its huge skull with a movable upper jaw. Having overtaken the victim, the tyrannosaurus put all its strength into hitting its head; movable cranial joints, like shock absorbers, softened the impact reaction. Tyrannosaurus prey was almost certainly large herbivorous dinosaurs, too large and dangerous for smaller theropods. It is estimated that adult tyrannosaurs weighed up to 7 tons and, reaching a height of 5 m with a body length of up to 12-15 m, occupied an ecological niche that, due to their size, has no analogue in the modern fauna.
Egg Thieves
Some of the carnivorous dinosaurs of the late Cretaceous period, while remaining predators, took a different evolutionary path. These agile bipedal theropods were no larger in size than modern German shepherds. Unlike their relatives, they lost almost all their teeth, except for two, instead of which they formed a strong beak, reminiscent of a parrot's beak. These specialized predators, with strong front legs and a combed nape, were very similar in appearance to modern cassowaries, birds that live in the forests of New Guinea. "Parrot's beak" is an example of convergent evolution, where different animal species independently develop similar traits to achieve similar goals.
This ornithomimus (Ornithomimus - “bird imitator”) was the size of a modern ostrich, but, unlike it, had a long tail that helped maintain balance while running. This creature may well have eaten eggs, but some researchers believe that it was a herbivore.
In the case of oviraptor (“egg stealer”), a similar external factor may be food similar to the diet of modern parrots: nuts, plant seeds, fruits, eggs, although, most likely, oviraptors also ate small animals - reptiles and mammals.
Swift, reminiscent of modern ostriches, ornithomimids, and bipedal, dog-sized troodontids likely fed on small, defenseless animals and, along with other theropods mentioned, constituted the diversity of carnivorous reptiles of the Late Cretaceous.
Herbivorous crocodiles
Throughout their evolution, crocodiles remained predators, leading a semi-aquatic lifestyle in inland waters and deltas of large rivers. They reached their maximum species diversity at the beginning of the Cretaceous, and although the number of their species subsequently decreased markedly, in the Late Cretaceous there were still significantly more of them than now. True or "modern" crocodiles belong to the crocodile family (Crocodylia), a subgroup of the larger order (Crocodylia or Loricata). Their evolution began in the Late Cretaceous. The adaptability of crocodiles to their habitat can be judged by the fact that they have remained virtually unchanged for 65 million years.In the Late Cretaceous period, part of their numerous species were animals that we could hardly call crocodiles. Perhaps the most unusual among them was a small creature whose remains stunned the scientific community in June 2000. Named Simosuchus ("chicken-nosed crocodile"), it was discovered in the Late Cretaceous sediments of Madagascar. This crocodile was a very unusual ANIMAL: its skull is extremely short (in most crocodiles the snout is three times longer than the rest of the skull, but in Simosuchus these parts of the skull are almost equal). The front of the muzzle was almost flat. The lower jaw, unlike other crocodiles, was connected to the skull in its anterior rather than occipital part. The flat, leaf-shaped teeth with small tubercles at the edges of the square jaws are more reminiscent of the teeth of ankylosaurs. In many respects, the head of Simosuchus is also more similar to the head of an ankylosaur or turtle, which it also resembled with its short, armored body. Some features of its anatomical structure suggest that it could dig well in the ground, and swam quite differently from how modern crocodiles swim.
Movement of continents
Simosuchus was a pronounced herbivorous crocodile, about the size of a modern iguana, although it also fed on large insects and frogs. Its unusual body structure for crocodiles suggests that this small animal was in an ecological niche occupied by armored ankylosaurs in other parts of the world.
We know of no ankylosaur remains from South America or Africa, and the reason for their absence from these continents lies in the configuration of the continents at the end of the Mesozoic. Ankylosaurs appeared in the Northern Hemisphere, apparently, some time after the southern and northern parts of the ancient protocontinent Pangea diverged, and therefore could not get to the southern continent, already separated from the northern by a vast expanse of water.
The presence of Simosuchus in Madagascar is consistent with the findings of several rare species of fossil crocodiles with similar anatomical structures. One of them, Uruguayasuchus from Uruguay, is very similar to Simosuchus. The similarity of the structure indicates an origin from the same evolutionary trunk, and since Uruguayasuchus originates from South America, the discovery of the remains of Simosuchus in Madagascar confirms its connection in the Late Cretaceous with South America (via Africa). From an evolutionary perspective, crocodylians were an incredibly successful group of reptiles. They even survived the mass extinction event at the end of the Cretaceous period, when dinosaurs completely disappeared from the face of the Earth.
Dinosaur extinction
One of the most significant events in the entire history of the Earth occurred about 65 million years ago. Several large groups of vertebrates became extinct during this time, including dinosaurs, as well as marine (mosasaurs, plesiosaurs, pliosaurs, and ichthyosaurs) and flying (pterosaurs) reptiles. Other vertebrates: frogs, lizards, crocodiles, snakes, mammals and turtles survived the disaster.There are a number of theories explaining this extinction: according to one of them, the cause is considered to be the collision of the Earth with a huge asteroid about 65 million years ago. Evidence of such a collision is a crater with a diameter of 110 km on the seabed near the Mexican Yucatan Peninsula, formed at this time. Pieces of quartz called “impact” are found here: it has a unique crystal structure, characteristic only of quartz from places where nuclear explosions were carried out. And a layer of sediment containing iridium (a rare metal on Earth that is part of many asteroids) was discovered in rocks of this age around the world. The very process of dinosaur extinction continues to cause heated debate.
A trace of a meteor shower, possibly causing the so-called. "global winter" that dinosaurs could not survive.
- Did you know?
- Some paleontologists and geologists believe that the reason for the extinction of dinosaurs was the powerful volcanic eruptions over several millennia at the end of the Cretaceous period, during which huge amounts of volcanic gas and dust were released into the atmosphere, causing global climate change. The site of these eruptions in India is called the Deccan Traps (northwestern part of the Deccan Plateau).
- According to some paleontologists, the metabolic rate of dinosaurs was much higher than that of modern reptiles, and therefore they required so much energy obtained in the form of food that they could not withstand food shortages during the “global winter” that came Earth after a collision with an asteroid.
- Before the asteroid impact, the world resembled a greenhouse with a constantly warm climate. However, this was not the kind of greenhouse that could arise under human influence in the 21st century, since the climate in that era had developed over the previous millions of years and was even and stable.
Why did dinosaurs become extinct?
Dinosaurs, which conveniently went extinct about 65 million years ago, were eerie creatures - thick-skinned, armored, all teeth and claws. For example, Tyrannosaurus rex, the largest land predator of all time, could easily bite a rhinoceros or an elephant in half with one subtle movement of its terrible jaws. And the weight of herbivorous lizards with columnar legs reached 30 and even 50 tons. And it is no coincidence that paleontologists, having unearthed the heavy bones of another antediluvian reptile, called it a seismosaur, that is, a lizard that shakes the earth. The length of this monster, according to cautious estimates by scientists, was 48–50 meters.
For nearly two hundred million years, magnificent reptiles were the absolute masters of all three elements: agile ichthyosaurs, reminiscent of modern dolphins, swam in the primeval seas, multi-ton diplodocus walked the earth, and toothy pterodactyls looked out for prey in the sky. (By the way, the wingspan of these flying monsters could sometimes reach 16 meters, which is quite comparable to the dimensions of a modern combat fighter.)
Tyrannosaurus rex skull
And then suddenly the giant lizards began to rapidly die out, they were replaced by inconspicuous, small and unremarkable creatures leading a predominantly nocturnal lifestyle. Scientists already knew about sudden and catastrophic changes in the composition of the planetary biota at the end of the Cretaceous period in the 18th century, and since then this mysterious phenomenon has often been called the “Great Dying.”
What happened? Usually textbooks paint such a simple picture. A large and prosperous group of reptiles (both predatory and herbivorous), which populated all the ecological niches of the planet, suddenly and unexpectedly died - instantly and everywhere. And since these giants had no serious competitors at that time (mammals huddled on the margins of evolution and subsequently simply occupied an empty house), it is logical to look for some external reason. For example, a climate cataclysm (sharp cooling or, conversely, warming), a supernova explosion, accompanied by deadly fluctuations in the gamma-ray background, or a change in the magnetic poles, which temporarily deprived the planet of its protective shell.
For some time now, the asteroid hypothesis has become very popular. Allegedly, at the end of the Cretaceous period, a huge meteorite crashed onto the Earth, throwing billions of tons of dust into the stratosphere, which screened the surface of the planet, which led to the death of green plants, and after them, the rest of the fauna. In addition, the fall of such a meteorite could provoke a revival of terrestrial volcanism, which significantly aggravated the situation. It should be noted that serious paleontologists do not particularly support this point of view.
Where did the asteroid hypothesis come from? In the mid-1960s, in geological deposits dating back to the Cretaceous-Cenozoic period (approximately 67 million years ago), scientists discovered a layer of blue clay with an abnormally high content of the rare metal iridium (20 times more than the average in the earth's crust). Subsequently, many similar anomalies were found (in some of them the iridium concentration was 120 times higher than the background), and all of them turned out to be the same age - they lay on the Cretaceous-Cenozoic boundary.
Since there is very little iridium in the earth’s crust, and it is found in abundance in meteorite matter (primarily in iron meteorites, which are considered fragments of planetary cores), the American physicist Alvarez associated the iridium anomaly with the fall of an asteroid. He estimated its diameter at 10–12 kilometers and even indicated the location of the disaster - the Yucatan Peninsula, where he managed to find an impressive crater about 150 kilometers in diameter.
The fall of such an asteroid would greatly shake our planet: a tsunami wave of monstrous force and height would devastate the coasts tens and hundreds of kilometers inland, and a huge dust cloud would eclipse the sun for a long time. A six-month absence of sunlight would destroy green plants (photosynthesis processes would stop), and then (along the food chain) animals - both land and sea.
Since Alvarez put forward his impact hypothesis in 1980. impact- “blow”), a lot of time has passed. Today, several dozen iridium anomalies are known, and in geological deposits of very different ages, but it has not been possible to connect them with the mass death of flora and fauna. Moreover, geologists have at their disposal a number of craters much more impressive than the notorious Yucatan. The diameter of some of them reaches 300 kilometers, but nothing serious has happened to the planetary biota (and this has been reliably established). Which is quite natural, since the biosphere is by no means a children’s construction set, the elements of which can be shuffled and folded at random, but a stable homeostat that can effectively withstand various kinds of disturbances.
The famous Russian paleontologist K. Yu. Eskov notes:
In this sense, the situation with the Eltanin asteroid (about 4 km in diameter), which fell in the late Pliocene, about 2.5 million years ago, on the shelf between South America and Antarctica, is very indicative; the remains of an asteroid were recently recovered from a crater formed on the seafloor. The consequences of this fall look quite catastrophic: kilometer-long tsunamis threw marine fauna inland; It was then that very strange burials of fauna with a mixture of marine and land forms appeared on the Andean coast, and purely marine diatoms suddenly appeared in the Antarctic lakes. As for the distant, evolutionarily significant consequences, they simply did not exist (traces of this impact are contained within one stratigraphic zone), i.e., absolutely no extinctions followed all these terrible perturbations.
Thus, the picture that emerges is quite interesting. As soon as iridium anomalies began to be purposefully searched for, it immediately became clear that their strict connection with the mass death of dinosaurs (or any other organisms) was nothing more than an illusion. The fossil remains of Mesozoic dinosaurs clearly indicate that the catastrophic Cretaceous-Paleogene extinction scenario is no good, since some groups of dinosaurs disappeared long before the iridium anomaly, while others sank into oblivion much later. The process lasted for hundreds of thousands and millions of years, so there can be no talk of any rapidity.
Therefore, the asteroid hypothesis, as well as all other “impact” scenarios, can be archived with peace of mind, since they assume the immediate destruction of flora and fauna. Meanwhile, even the mass death of marine organisms at the end of the Cretaceous period (much more rapid than the extinction of dinosaurs) was instantaneous only by geological standards and lasted for a considerable period - according to various estimates, from 10 to 100 thousand years. As for reptiles, they did not become extinct overnight.
K. Yu. Eskov writes:
How so?! It’s very simple: the extinction of dinosaurs continued throughout the Late Cretaceous at a more or less constant rate, but starting from a certain point this decline ceased to be compensated by the emergence of new species; old species die out - and new ones do not appear to replace them, and so on until the complete destruction of the group. (An analogy: a country is losing a war not because the enemy began to inflict unprecedentedly high losses on it at the front, but for another reason - in the rear, tank and aircraft factories stopped due to lack of raw materials.) In other words, at the end of the Cretaceous there was no catastrophic extinction dinosaurs, but the failure of new ones to replace them (this, you see, noticeably changes the picture). This means that we can talk about a rather long natural process.
Alternative versions are no more convincing - for example, the hypothesis of a sudden change of magnetic poles or a supernova explosion near the solar system. Of course, magnetic polarity reversal is a very unpleasant thing, since streams of charged high-energy particles flying from the Sun are deflected in the magnetic field lines, forming onion scales of radiation belts. If our planet’s thick magnetic “coat” is torn off, then hard radiation will begin to freely reach the Earth’s surface.
But, firstly, the leapfrog of the magnetic poles is by no means an exotic, but a natural periodic process, and data from special studies, as a rule, do not reveal a relationship between global biosphere crises and changes in terrestrial magnetism. And secondly, the biosphere as a whole is a flawlessly adjusted homeostat that easily resists any outside interference.
A supernova explosion is a cataclysm on a galactic scale. If such an event occurs in the vicinity of the solar system (according to astronomers, this happens once every 50–100 million years), then the streams of X-ray and gamma radiation will not only destroy the ozone layer, but will also sweep away part of the earth’s atmosphere, provoking the so-called “effect highlands,” which not all organisms can survive. However, even in this case, extinction will most likely not be sudden, but will stretch over tens and hundreds of millennia. In addition, hard radiation and the effect of high altitudes should primarily affect the population of land and shallow waters, but in reality, as we know, the situation was exactly the opposite: the flora and fauna of the open sea, including microscopic ones, suffered the most, and of the inhabitants of land For some reason, only dinosaurs became victims of the Great Dying.
This amazing selectivity is generally the most vulnerable point of all impact hypotheses: indeed, why did dinosaurs become extinct, but crocodiles survived and lived safely to this day? Perhaps the unprecedented popularity of various kinds of “impact” versions is mainly due to the successes of observational astronomy over the past 20–30 years.
Since we are busy debunking idle myths, it is necessary to say a few words about the fauna of the Mesozoic. In almost any textbook you can read that the Mesozoic era was the era of dinosaurs, and the Cenozoic is the age of mammals that replaced them. Meanwhile, this is a typical scientific prejudice.
Few people know that mammals were contemporaries of dinosaurs (they appeared on Earth almost simultaneously - at the end of the Triassic) and happily coexisted with them for 120 million years. Moreover, if you sort through the fossil remains of all Mesozoic creatures, you will find that the number of mammal species significantly exceeded the number of dinosaur species. True, our distant ancestors, who vaguely resembled South American opossums, were at that time small and timid creatures, leading a predominantly nocturnal lifestyle.
With certain reservations, the term “Great Extinction” itself can be called a pseudo-scientific myth. And if we are talking about scale, then the Permian-Triassic extinction should be called great - a grandiose biosphere cataclysm that happened at the turn of the Paleozoic and Mesozoic. It was generally the largest in the history of our planet: if at the end of the Cretaceous about a quarter of families disappeared into oblivion, then during the Permian-Triassic extinction, 50% of families, 70% of genera and 90% of species disappeared from the face of the Earth. In addition, all marine ecosystems have changed radically. It would be worth noting that all attempts to link the Late Permian crisis with the asteroid impact ended in absolute failure - no traces of the impact impact could be found in the corresponding horizons.
So what caused the extinction of the dinosaurs? One of two things: either climatic changes at the boundary of the Cretaceous and Cenozoic, or purely “natural” reasons - a radical restructuring within ecosystems and a change in communities.
Let's figure it out in order. We are accustomed to the fact that the planetary climate is characterized by pronounced latitudinal zonality: tropical rainforests grow on the equator, to the south and north of them lie savannas, periodically moistened, where countless herds of ungulates graze, and even further to the north and south there is a strip of sun-scorched deserts and semi-desert. The subtropics give way to temperate forests - deciduous and coniferous, and they gradually give way to the cold tundra, where almost nothing grows. Well, at the poles there is eternal frost and eternal ice.
But it was not always so. The Mesozoic is a classic example of a thermal era, when there was no latitudinal zonation, and the global climate resembled the current subtropical Mediterranean type. In the high latitudes and even at the pole it was warm and quite comfortable, but at the same time it was not too hot at the equator. In short, the temperature gradient - both seasonal and daily - was barely perceptible. But at the end of the Cretaceous, the thermoera was replaced by a cryoera with latitudinal temperature differences.
Dinosaurs were cold-blooded (poikilothermic) animals. Not being able to regulate their body temperature “from the inside,” they were entirely dependent on their environment, but in the even climate of the Mesozoic, this did not cause them much trouble. If the outside heat comes in in abundance, and the impressive dimensions do not allow it to cool down overnight (most dinosaurs were large creatures), then maintaining a high body temperature will not be difficult. And all this without any participation of their own metabolism, on which mammals spend 90% of the energy they consume through food.
This curious phenomenon was called inertial homeothermy (warm-bloodedness), and many scientists believe that thanks to this valuable quality, dinosaurs became the rulers of the Mesozoic. And when the climate changed radically at the end of the Cretaceous, the giant lizards disappeared.
It would seem that we have found the answer, but again something doesn’t add up. Why did dinosaurs become extinct, while other reptiles - also cold-blooded - continue to exist to this day? Why did the Cretaceous crisis affect mainly marine inhabitants, while land creatures survived it calmly? Why did some groups of dinosaurs begin to actively die out long before the fateful calendar date, while others slowly lived out their lives in the Paleogene?
Perhaps it makes sense to look for the answer elsewhere - in the structure of ecosystems? Let us remind the reader about the inconspicuous Mesozoic mammals, which lived side by side with lizards for 120 million years, without interfering with them in any way. These small insectivorous creatures, similar to modern opossums or hedgehogs, occupied their own ecological niche, which no one encroached on. But in the Cretaceous period the situation changed radically.
K. Yu. Eskov describes these events as follows: evolution spurred the sluggish metabolism of primitive mammals and created a “phytophage in a small size class” on this new metabolic basis. (Herbivorous dinosaurs were very large animals.) And if a small phytophage appeared, then a predator would certainly arise, which would not limit itself to hunting close relatives, but would grab everyone within its power. Therefore, a baby dinosaur - a small, defenseless lizard that does not have inertial homeothermy - will instantly become a tasty prey for such a 24-hour active predator.
The version is undoubtedly interesting, but it does not answer all the tricky questions. And here genetics, understood in the broad sense of the word, will come to our aid. Let's talk about marginality as the antipode of narrow specialization, because this is how the organic world develops.
Let us once again remember the Mesozoic mammals, who voluntarily gave up the world to magnificent reptiles and vegetated on the sidelines of evolution. Huddled in remote corners, they were the real outcasts, since they occupied those few ecological niches that the ruling class ignored with magnificent negligence.
The food supply of herbivorous dinosaurs were gymnosperms and ferns, which were widespread in the Devonian. The angiosperm, or flowering, flora, which appeared at the beginning of the Cretaceous period, was forced to settle in the margins, since gymnosperms dominated. Thus, flowering plants were just as marginal as small Mesozoic mammals. They had no choice but to occupy empty lands where there were no established communities of gymnosperms: landslides, burnt areas, river banks, that is, such biotopes that are usually called “disturbed.” And the species themselves that settle in such conditions are called “coenophobic” by biologists, that is, they are afraid of communities and prefer to exist separately.
However, the tactical loss ultimately turned out to be an important strategic advantage. Firstly, the flowering plants that had settled on the “bad” lands no longer allowed gymnosperms there, and secondly, they had a flower, which played a decisive role in the struggle for existence. If gymnosperms, for the reproduction of their own kind, relied entirely on the wind, which passively carried their pollen, and therefore were forced to settle in clusters, then flowering plants actively attracted insects, which increased their viability by an order of magnitude.
The existence of flowering plants did not depend on the elements, and the angiosperm flora could afford the luxury of living in scattered wastelands. In addition, a new type of flora has learned to form herbaceous forms that not only effectively counteract erosion, but also quickly take over vacant land.
The change in plant communities turned into a real disaster. Contrary to popular belief, not only dinosaurs became extinct, but also 25% of the Mesozoic families of invertebrates - cephalopods and bivalves, single-celled radiolarians, diatoms, foraminifera and other representatives of planktonic organisms. Their calcium shells formed enormous deposits, which is why this period of the geological record was called the Cretaceous.
Thus, yesterday's inconspicuous outcasts - flowering plants and mammals - crushed the dominant fauna and flora of the Mesozoic.
The onset of flowering plants is now commonly called the great angiospermization (from lat. angiospermae- "angiosperms"). When the new type of flora began to decisively predominate, what always happens when the foundation is destroyed: the building simply collapsed. After all, the plant kingdom is precisely the foundation on which the floors of herbivorous animals and predators stand, and they are connected to each other not only by food chains, but also by more complex relationships.
Dinosaurs tried to master a new diet - they developed beaks and powerful dental batteries for grinding highly abrasive food. However, this did not work out well for them, especially in cereal pasture systems, where they obviously lost to ungulates. In addition, herbaceous flowering forms form turf, which reduces erosion and the runoff of organic matter into fresh waters and the oceans, which has dealt a severe blow to marine invertebrate communities.
The thing is that the overwhelming majority of the creatures that inhabited the planet in the Late Cretaceous moved too far along the path of narrow specialization. For the time being, this gave them excellent chances of survival, but every advantage sooner or later turns into a disadvantage. Attachment to gymnosperm communities eventually played a cruel joke on the lizards: when the flowering plants went on the offensive, taking away one territory after another from the previous masters of life, the mammals easily joined the newly formed communities. But dinosaurs were unable to do this and found themselves in an evolutionary dead end, since their adaptive resources had long been wasted. And for marginalized mammals, this turn of events was only to their advantage. Having survived an explosion of speciation under new conditions, they populated the entire planet.
Of course, not only such large taxa as a class of animals or a phylum of plants can be marginal. Individual biological species, as a rule, also do not exhibit complete uniformity across the entire set of characteristics. Moreover: the higher the genetic diversity of a species or population, the greater its adaptive potential. Such a community will almost always find a way to prolong its existence under changed conditions. And even with a stable and measured life, intraspecific marginals can play an important role.
For example, winged individuals are rarely found in populations of wingless water striders. There are very few of them - only 4%. They have genetic differences, but at the same time they can interbreed with their wingless companions and produce offspring. It turned out that these flying degenerates are capable of migrating over fairly long distances, thus ensuring genetic continuity between the water-dwelling population of all water bodies. Four percent of the marginalized population is more than enough to accomplish this task.
It must be said that almost every biological species has, just in case, an emergency reserve in the form of a rare genotype or an unusual form, which allows it to survive difficult times. Let us repeat once again: the genetic diversity of a species or population is the key to its evolutionary success, so the marginalized should be treated not only with respect, but also with care.
So, the emergence and widespread distribution of flowering plants at the end of the Early Cretaceous (about 30 million years before the death of dinosaurs) not only radically changed the structure of continental communities, but also destroyed the Mesozoic dinosaurs, which had lost their plasticity, hopelessly stuck in dead ends of evolution. Of course, climatic disturbances could also play a role, but the key event, the starting point, was almost certainly this fact - the onset of angiosperms.
From the book The Vanished World author Akimushkin Igor IvanovichAre they all extinct? Summer 1933. Walking along the shore in the morning, engineer A. Palmer suddenly heard a deafening splash, as if... However, let’s listen to the engineer: “I thought that a storm had suddenly begun, but not a single leaf moved on the trees. Looking at the lake, I
From the book of Dinosaur, search in the depths author Kondratov Alexander Mikhailovich1. Dinosaurs and relatives
From the book The Newest Book of Facts. Volume 1 [Astronomy and astrophysics. Geography and other earth sciences. Biology and Medicine] authorDinosaurs in all dimensions “The dragon, flying, approached the ground, fell and died. His bones went deep into the ground and became stone...” So says the old Mongolian fairy tale. “Dragon bones,” the fossilized remains of dinosaurs, were long known to the nomadic Mongols
From the book Anthropological Detective. Gods, people, monkeys... [with illustrations] author Belov Alexander IvanovichChapter Six: Dinosaurs in the USSR? The North is waiting for discoveries... Only quite recently, with the help of aviation, the endless expanses of Chukotka were put on geographical and topographic maps. Only in the 20th century was a huge archipelago discovered in the Arctic Ocean - Severnaya Zemlya. IN
From the book In the Wilds of Time author Chizhevsky German MikhailovichUnknown dinosaurs The mysterious death of dinosaurs gives rise to many hypotheses (the last of them explains the extinction of dinosaurs by the fall of an asteroid, but this again is a hypothesis, not a proven fact). Almost every year brings new discoveries, in the light of which dinosaurs
From the book Chimera and Antichimera author Shvetsov Mikhail Valentinovich From the book Evolution author Jenkins MortonWHERE DID DINOSAURS COME FROM? Recently, you can often hear a question that has already become rhetorical: why did dinosaurs become extinct? And with all the variety of answers, for some reason another question does not arise at all: where did these same dinosaurs come from on Earth? Well, it’s boring and
From the book The Newest Book of Facts. Volume 1. Astronomy and astrophysics. Geography and other earth sciences. Biology and medicine author Kondrashov Anatoly PavlovichDinosaurs, or divolizards The descendants of archosaurs especially multiplied in the second half of the Mesozoic era. They were exceptionally diverse. Some remained predators with short front legs. They all had a thick and very strong tail, which was
From the book Life in the Depths of Ages author Trofimov Boris AlexandrovichHow dinosaurs developed Expeditions working on excavations in the Gobi Desert found nests with eggs several times. It has been suggested that these are eggs of large turtles. But the latest research has shown that these are dinosaur eggs. Dinosaur eggs have been discovered in
From the book Evolution [Classical ideas in the light of new discoveries] author Markov Alexander VladimirovichConversation 8. Dinosaurs - ionizing radiation - humans In 1991, it was 150 years since the discovery of the Permian system by the English geologist Roderick Murchison. As written in the scientific biographical book by P.K. Chudinov, Ivan Antonovich Efremov (M.: Nauka, 1987), Murchison decided
From the author's bookDINOSAURS During the Triassic period (245–202 million years ago), the reptile archosaurs (ruling lizards) evolved into four main groups: the two orders of dinosaurs, pterosaurs and crocodiles. Two groups of dinosaurs (lizard and ornithischians) were no more than
From the author's bookOrnithischian dinosaurs are scientifically called Ornithischia. The shape of their pelvis is such that the leg bones point down, parallel to each other. All of them were herbivores and during the era of the spread of these dinosaurs - in the Jurassic and Cretaceous periods (202-65
From the author's bookLizard-pelvic dinosaurs (Saurischia), which appeared earlier than another group, had a pelvic structure similar to other reptiles. Their two leg bones diverged in different directions. Some of them were herbivores, others were carnivores. They often
From the author's bookWhy did dinosaurs become extinct? According to the theory that currently has the largest number of supporters, an asteroid with a diameter of about 10 kilometers fell on Earth 65 million years ago. Even the place of his fall has been established - the Yucatan Peninsula in Mexico. Energy released
From the author's bookDINOSAURS - AMAZING AND TERRIBLE LIZARDS The ancestors of these lizards were the “early reptiles” - thecodonts, which also gave rise to crocodiles, flying lizards and birds. These were small, the size of a rooster or a little more, agile lizards who lived at the end of the Paleozoic and at the beginning
From the author's bookDinosaurs master the air The modern world is replete with flying creatures - insects, birds, bats; there are others who, although not real flyers, are no longer quite land dwellers - tree frogs, squirrels, woolly wings, lizards - “flying dragons”.
