Quaternary period. Quaternary period of the Cenozoic era: description, history and inhabitants Why is the Quaternary period sometimes called anthropogenic
The Quaternary period lasted about 1-1.5 million years. Most of the time occurred during the Ice Age - Pleistocene. The last century, the Holocene, lasted 12-20 thousand years. Even at the beginning of the Pleistocene, the fauna of Europe and the USSR was quite thermophilic and retained many subtropical species. During the Pleistocene, the territories of Eurasia and North America were subject to giant glaciations four times. The tongues of the glacier, sliding down from Scandinavia, reached Kyiv, Kharkov and Voronezh. The glaciers of Antarctica, Greenland, Iceland, Severnaya Zemlya, Franz Josef Land, Pamir and Tien Shan are remnants of Quaternary glaciations.
During the Quaternary period, mastodons (ancient elephants), mammoths, saber-tooth tigers, giant sloths, and big-horned peaty deer became extinct. Ancient hunters played a major role in the extinction of large mammals. They exterminated the mammoth and woolly rhinoceros in Eurasia, mastodons, horses, giant sloths, and sea cows in America. The disappearance of many large predators (cave lion, cave bear) was apparently due to the fact that man destroyed their victims - large ungulates.
The negative heat balance in the glaciation zone led to the fact that water vapor condensed in the form of snow, and the melting of ice and snow annually produced less water than snowfall. The accumulation of gigantic ice reserves on land has led to a significant drop in the level of the World Ocean (by 60-90 m). As a result, land bridges arose between continental Europe and the British Isles, Asia and North America, the Amur region and Sakhalin, between the Indochina Peninsula and the islands of the Sunda archipelago. Animals and plants were exchanged across these areas of land.
The same land bridges that served as routes of exchange between land animals and plants prevented the exchange of fauna and flora in previously connected seas. The absence of a land bridge between Asia and Australia preserved the life of the most primitive mammals - cloacal and marsupials, which were replaced by placental mammals on other continents in the Tertiary period.
In the Old World (with the exception of Madagascar), humans settled at least 500 thousand years ago. Before the last glaciation (about 35-40 thousand years ago), ancient hunters from Asia crossed a land bridge in the area of the modern Bering Strait to North America, which they settled as far as Tierra del Fuego. As the glaciers melted, the territories freed from under the glaciers were re-populated by humans.
About 10,000 years ago, in warm temperate regions of the Earth (Mediterranean, Middle East, India, China, Mexico, Peru), the domestication of animals and the introduction of plants into culture began. The “Neolithic revolution” began, associated with the transition of man from gathering and hunting to agriculture and cattle breeding.
Rapid human activity: plowing of lands, uprooting and burning of forests, grazing of pastures and trampling of grass stands by domestic animals, direct extermination - led to the extinction or reduction of the ranges of many steppe animals (wild bull - aurochs, wild horse - tarpan, etc.), to the expansion of areas deserts (Sahara, Karakum, etc.), the appearance of shifting sands.
The entire Quaternary period in the Old World took place with the participation and significant influence of man. This mainly determined the species composition of the organic world that currently exists, influenced the modern geographical distribution of organisms, created modern biogeocenoses and led to today's zonation. Both land bridges and isolation by glaciers played a huge role in distribution and speciation. Many species and subspecies were formed during the Quaternary period. Cm.
Changes associated with climate change have occurred more than once in the history of the Earth, but rarely have any of them occurred as rapidly as they did 1.6 million years ago. The Quaternary period is divided into two geological eras: the Pleistocene, which lasted throughout the last Ice Age, and the Holocene, which began about 10 thousand years ago, when the ice retreated for the last time.
Woolly mammoths appeared in Europe and Asia, and they moved to North America along the land “bridge” that ran across the Bering Sea. The huge mound on their head is a reservoir of energy-intensive fat.
Great changes.
The European cave bear (pictured left) is an Ice Age animal known from remains found in caves where it hibernated.
The extent of glaciations is much greater than individual, albeit long periods of cooling. During the ice age, certain temperature deviations from their average values occur, and any sharp drop in temperature is accompanied by glaciation - a widespread expansion of the ice sheet, that is, a shift of polar ice to the south and the sliding of mountain glaciers. And during periods of warming, the so-called interglacials, the opposite happens: the ice retreats. For example, we are currently living in the period of the next interglacial, which began in the Holocene. The onset of ice ages cannot be predicted, although these processes are almost certainly associated with changes in the Earth's orbit as it rotates around the Sun. Like changes in average temperature values and, accordingly, the area of ice cover, changes in the Earth's solar orbit also affect flora and fauna in their own way. And one of these influences is expressed in a decrease in sea level due to the freezing of water and its transformation into ice. Another influence affects the overall pattern of precipitation: during the warm season, other areas become drier than usual. Due to climate change in the Pleistocene, most
Plants suffered, especially in the far north and south, where slowly advancing ice literally cut off the top layers of soil along its path. As for land animals, lowering sea levels often benefited them: they could move along newly formed land “bridges” to places previously inaccessible to them.
Mammoths and mastodons.
Unlike woolly mammoths, woolly rhinoceroses did not move from Asia to North America, but they spread from the northern reaches of the Asian tundra to the steppes much to the south. Like modern rhinoceroses, their horns served both to intimidate rivals and for self-defense.
At the time when they flourished, and this was in the Pleistocene, the limits of the ice cover extended to the places where London and New York now stand. And to the south of the boundaries of these vast continental ice lay the tundra - vast open expanses of grassy wetlands, crossed by rivers that were replenished with glacial meltwater and carried them to the seas. These were harsh lands, however, despite the cold, the summer turned them into a rich source of plant food. It was an excellent habitat for warm-blooded animals. Well, the most famous mammals of the Ice Age were mammoths and mastodons, which were part of two groups of the same elephant branch. The steppe mammoth, Mammuthus trogontheri, which lived in Europe about 500 thousand years ago, was one of the first to adapt to the harsh cold, growing a long, dense coat of hair. Unlike modern elephants, it had a rather convex crown and sloping back, and in males the tusks reached a length of more than 5 m. The well-known six-hundredth mammoth, Mammuthus primigenius, was distinguished by a more dense build, despite its height being less than 3 m. Its tusks were also not small - most likely they served it to tear apart the snow in search of food. The American mastodon, Mammut americanum, which lived in coniferous forests along the southern reaches of the tundra, looked exactly the same. Steppe mammoths died out quite early, while hairy mammoths and mastodons survived much longer. According to some estimates, mastodons died out about 8,000 years ago, while the six-hundredth mammoths survived for another two millennia. And people—primitive hunters—are probably to blame for the deaths of both.
Ice Age Rhinos.
Woolly rhinoceroses, Coelodonta antiguitatis, also lived in the northern tundra, whose relatives are now found mainly in warm regions. With a height of over 2 m, woolly rhinoceroses had a pair of strong horns made of intertwined and hardened fibers - a characteristic feature that distinguishes rhinoceroses from other ungulate mammals. They had a dense build and long hair, like all ice age mammals, because a large body generates a lot of heat from food, and thick hair helps to retain it. Woolly rhinoceroses lived in Europe and Siberia, and they lived until the end of the Pleistocene, when the ice retreated again. Their frozen remains have been found in layers of permafrost, as well as in oil formations in parts of Central Europe. A member of another group of Ice Age animals, Elasmotherium, appears to have had a much larger horn than any member of the rhinoceros family. Elasmotherium itself was comparable to a modern white rhinoceros, but its horn was more than 2 m long.
Fight for survival in winter.
With such spreading antlers, the Irish elk was undoubtedly the most majestic animal that inhabited Europe and northern Asia during the Ice Age. In total, there were several species of this amazing deer, the owner of luxurious antlers, which he changed from year to year.
For tundra herbivores, summer was a time of plenty, and winter was a time of hardship. With the onset of cold weather, many herbivorous mammals moved south - to forest regions, where they could hide from the cold, although there they had to be content with very meager food - tree bark and buds. These animals included reindeer and the so-called Irish moose, the remains of which were discovered in various parts of Northern Europe and Asia. Modern reindeer follow the same migration routes, and as for the Irish moose, they soon became extinct. However, in some remote corners of Europe they probably disappeared only 500 years before the birth of Christ. Unlike herbivores, cave bears spent the winter in hibernation. In some European caves, scratches have been preserved on the clay walls - obvious traces of the claws of bears digging their lairs.
Burial ground at Rancho La Brea.
Some very clear traces of animal life during the Pleistocene were found not somewhere in the distant northern regions, but almost in Los Angeles itself - in the famous tar swamps of Rancho La Brea, the world's largest natural burial ground for fossil remains. During the Ice Age, there were basins filled to the top with viscous asphalt, which became traps for many large animals. In the late Pleistocene, the climate here was cooler and wetter than today, and this fertile land was home to a great variety of different animals - mammoths, giant sloths and saber-toothed tigers. From above, tar swamps were often covered with torn, withered plants, and in winter, when the asphalt froze and hardened, animals laid paths along it. In the summer, under the influence of the sun's heat, the asphalt thawed and again turned into a viscous black slurry, and the animals, following the winter trail, immediately got stuck in it without any hope of getting out. When they began to struggle desperately, clinging to life, they made such a noise that scavengers flocked to him, and soon they also fell into a trap. After each such summer, which reaped an abundant bloody harvest, winter rains brought sand and other sedimentary rocks into the burial ground - this is how the petrification process began. Unlike most other fossils, those at Rancho La Brea are preserved in their original bone form. The cover of viscous asphalt was so dense that it did not allow air to pass through, and the animal skeletons lay there in excellent condition for 10 thousand years.
Treasures at the bottom of the swamps.
Currently, most of the tar marshes have been dug up to the very bottom, which was literally strewn with fossil remains of the late Pleistocene. The bones of individuals from about 60 species of mammals and more than 2,000 skeletons of saber-toothed tigers alone were recovered from the surface. The largest victims turned out to be mammoths, and the smallest were flying insects, who fell into an insidious trap, clearly due to a misunderstanding: it looked too much like the earth’s surface from above. This bitter fate did not escape the birds either. And here the fragile bird skeletons were preserved intact. The only ones who managed to avoid deadly traps were nocturnal animals. And most likely because after sunset the surface of the swamps froze. Ice Age California (pictured)... 20 thousand years ago, a huge mammoth got stuck in a tar swamp - and immediately became the prey of a saber-toothed tiger, which furiously fought off scavengers gathered for a bloody feast - storks, vultures and giant wolves, the largest representatives of the canine family . The participants in this feast mostly died out about 10 thousand years ago.
Bird kingdoms.
The giant moa, Dinornis maximus, was among the largest of two dozen bird species whose remains have been discovered in New Zealand. Before the arrival of immigrants from Polynesia on the island, about a thousand years ago, life was quite easy, especially since there were no land mammals, except for flying mice, nearby. An adult giant moa carried more than 2.5 kg of stones in its stomach, which facilitated its digestion process. Moas laid only one egg at a time.
Although the largest herbivores of the Ice Age were mammals, some remote islands such as Madagascar and New Zealand had no such land mammals at all. Among the giants there were birds that reached truly gigantic sizes. For example, in Madagascar, elephant birds reigned, weighing about half a ton - epiornis, Aepyornis maximus, which left a memory of itself in the form of the world's largest bird egg. New Zealand became famous for its moa: representatives of one of its species, Dinornis maximus, were over 3.7 m tall, thus being the tallest birds in nature. Such birds could develop unhindered due to the fact that on the distant islands where they lived there was not a single mammalian predator that would encroach on them or their chicks. Most of the giant birds ate seeds, fruits and tree roots. They absorbed food along with so-called stomach stones, like gastroliths that dinosaurs swallowed. The giant birds successfully survived the climate changes that occurred at the end of the last ice age, but, alas, they failed to survive after people moved to the islands with their spears, bows, arrows and dogs. The last Madagascar elephant bird appears to have gone extinct 1,000 years ago, and the last of the moa even earlier, 1,800 years ago.
Extinction of Pleistocene species.
The most striking fact about the life of ice age animals is that, by geological standards, they existed for only a short time - only a few of them could compete in longevity with the moa, and the vast majority of large mammals flourished even 10 thousand years ago. When the last glaciation ended, thousands of their species suddenly became extinct. North America suffered more than any other region from the widespread extinction: three-quarters of large mammals died out there, including those that sank into the tar swamps of Rancho La Brea. What is the reason for such a sudden and widespread pestilence? Some paleontologists attribute this mainly to a sharp climate change caused by the next retreat of ice and the subsequent warming.
According to this hypothesis, unexpected changes in plant life - and among other things, the afforestation of the tundra - deprived many mammals of their main sources of food. But the same thing has happened more than once before, and without such devastating consequences. Therefore, most paleontologists tend to see a completely different reason for this - the rapid spread of primitive hunters. According to this theory, the great migration of people was accompanied by the mass extermination of large animals, which, in turn, led to the destruction of natural food chains, which were then never restored. The giant sloth, Megatherium, lived in South America during the Ice Age. Being the size of a modern elephant, it easily stood on its hind legs, and with its front legs, with long claws at the end, it grabbed the upper branches of trees, bent them towards itself and ate the foliage from them. Although modern sloths belong to the same group of mammals, they rarely come to land.
A characteristic feature of the Quaternary period is the formation of the biosphere, that is, the thin air, water and soil shells of the globe in which life exists. The biosphere was formed over millions of years from a lifeless geosphere that developed over several billion years. It is for this reason that, unlike the climates of ancient times, when the biosphere was absent, the climatic conditions of the Quaternary period can correspond to the range of possible climate changes in the future.
The last 1.5-2 million years were characterized by the alternation of long glacial periods with an average duration of 70-120 thousand years with shorter interglacial periods of 15-20 thousand years. The penultimate warm interglacial period occurred 75-120 thousand years ago. The history of civilization falls on the last interglacial period, which began approximately 10-15 thousand years ago, at the end of which we are currently living. This period was called the Holocene.
According to paleoclimatic data, over the past 2 million years, the average temperature of the Earth was close to the current one, i.e., about 15 ° C, and fluctuated within ±5-10 ° C during the transition from glacial to interglacial periods. In Fig. Table 1 shows the results of model calculations of the Earth's temperature over the last 4.5 mlH. years. It should be borne in mind that even for this time the term “glacial-interglacial” periods did not mean that the Earth was completely covered with ice or free of it. There is reason to believe that the Arctic Ocean has never been completely free of ice, and the Antarctic continent has always been covered with an ice shell.
The most detailed data, thanks to drilling and analysis of continental ice columns in Greenland, Antarctica and other areas of the globe, are available on the climate of the last 150 thousand years. The accuracy of the analysis of ice columns for the period of the last 50 thousand years has increased significantly as a result of the application of methods of radiocarbon analysis of data on variations in the 18 O / 16 O isotope ratio.
In Fig. Table 2 shows the results of analyzes of the Earth's climate over the past 130-140 thousand years. One curve characterizes the results of the analysis of ice columns in Greenland for oxygen, the other - in the mountains of France - for radiocarbon. Both analyzes independently point to the presence of the last ice age approximately 15-80 thousand years ago and the onset of the last interglacial period 10-15 thousand years ago. The alternation of these periods occurred in the northern and southern hemispheres.
This issue was most fully studied during the implementation of the American Climap program (climate mapping). Landscapes, water surface temperatures, orography were restored for the last 450 thousand years and in more detail for the last ice age of the Pleistocene. Using spectral analysis methods of various indirect climate indicators, three periodicities of climate fluctuations were established.
The period of 100 thousand years is associated with almost the same period of fluctuation of the eccentricity of the earth's orbit (the ratio of the focal distance from the Sun to the Earth to the length of the main axis of the earth's orbit). The periodicity of approximately 40-43 thousand years is associated with periodic changes in the angle of inclination of the equatorial plane to the plane of the Earth's orbit. The third period of about 19-23 thousand years is associated with the precession of the earth's orbit.
Thus, fluctuations in glacial-interglacial periods during the Pleistocene era were largely due to changes in solar radiation coming to the Earth as a result of fluctuations in the parameters of the Earth's orbit. Below we will look at other factors responsible for climate change.
The periods of the geological history of the Earth are epochs, the successive changes of which shaped it as a planet. At this time, mountains were formed and destroyed, seas appeared and dried up, ice ages succeeded each other, and the evolution of the animal world took place. The study of the geological history of the Earth is carried out through sections of rocks that have preserved the mineral composition of the period that formed them.
Cenozoic period
The current period of Earth's geological history is the Cenozoic. It began sixty-six million years ago and is still going on. The conventional boundary was drawn by geologists at the end of the Cretaceous period, when mass extinction of species was observed.
The term was proposed by the English geologist Phillips back in the mid-nineteenth century. Its literal translation sounds like “new life.” The era is divided into three periods, each of which, in turn, is divided into eras.
Geological periods
Any geological era is divided into periods. There are three periods in the Cenozoic era:
Paleogene;
The Quaternary period of the Cenozoic era, or Anthropocene.
In earlier terminology, the first two periods were combined under the name "Tertiary period".
On land, which had not yet completely divided into separate continents, mammals reigned. Rodents and insectivores, early primates, appeared. In the seas, reptiles were replaced by predatory fish and sharks, and new species of mollusks and algae appeared. Thirty-eight million years ago, the diversity of species on Earth was amazing, and the evolutionary process affected representatives of all kingdoms.
Just five million years ago, the first apes began to walk on land. Another three million years later, in the territory belonging to modern Africa, Homo erectus began to gather in tribes, collecting roots and mushrooms. Ten thousand years ago, modern man appeared and began to reshape the Earth to suit his needs.
Paleography
The Paleogene lasted forty-three million years. The continents in their modern form were still part of Gondwana, which was beginning to split into separate fragments. South America was the first to float freely, becoming a reservoir for unique plants and animals. In the Eocene era, the continents gradually occupied their current position. Antarctica separates from South America, and India moves closer to Asia. A body of water appeared between North America and Eurasia.
During the Oligocene epoch, the climate becomes cool, India finally consolidates below the equator, and Australia drifts between Asia and Antarctica, moving away from both. Due to temperature changes, ice caps form at the South Pole, causing sea levels to drop.
During the Neogene period, the continents begin to collide with each other. Africa “rams” Europe, as a result of which the Alps appear, India and Asia form the Himalayan mountains. The Andes and rocky mountains appear in the same way. In the Pliocene era, the world becomes even colder, forests die out, giving way to steppes.
Two million years ago, a period of glaciation begins, sea levels fluctuate, the white caps at the poles either grow or melt again. The flora and fauna are being tested. Today, humanity is experiencing one of the stages of warming, but on a global scale the Ice Age continues to last.
Life in the Cenozoic
The Cenozoic periods cover a relatively short period of time. If you put the entire geological history of the earth on a dial, then the last two minutes will be reserved for the Cenozoic.
The extinction event, which marked the end of the Cretaceous period and the beginning of the new era, wiped out all animals larger than the crocodile from the face of the Earth. Those who managed to survive were able to adapt to new conditions or evolved. The drift of the continents continued until the advent of people, and on those of them that were isolated, a unique animal and plant world was able to survive.
The Cenozoic era was distinguished by a large species diversity of flora and fauna. It is called the time of mammals and angiosperms. In addition, this era can be called the era of steppes, savannas, insects and flowering plants. The emergence of Homo sapiens can be considered the crown of the evolutionary process on Earth.
Quaternary period
Modern humanity lives in the Quaternary epoch of the Cenozoic era. It began two and a half million years ago, when in Africa, great apes began to form tribes and obtain food by collecting berries and digging up roots.
The Quaternary period was marked by the formation of mountains and seas and the movement of continents. The earth acquired the appearance it has now. For geological researchers, this period is simply a stumbling block, since its duration is so short that radioisotope scanning methods of rocks are simply not sensitive enough and produce large errors.
The characteristics of the Quaternary period are based on materials obtained using radiocarbon dating. This method is based on measuring the amounts of rapidly decaying isotopes in soil and rock, as well as the bones and tissues of extinct animals. The entire period of time can be divided into two eras: the Pleistocene and the Holocene. Humanity is now in the second era. There are no exact estimates yet of when it will end, but scientists continue to build hypotheses.
Pleistocene era
The Quaternary period opens the Pleistocene. It began two and a half million years ago and ended only twelve thousand years ago. It was a time of glaciation. Long ice ages were interspersed with short warming periods.
One hundred thousand years ago, in the area of modern Northern Europe, a thick ice cap appeared, which began to spread in different directions, absorbing more and more new territories. Animals and plants were forced to either adapt to new conditions or die. The frozen desert stretches from Asia to North America. In some places the ice thickness reached two kilometers.
The beginning of the Quaternary period turned out to be too harsh for the creatures that inhabited the earth. They are accustomed to a warm, temperate climate. In addition, ancient people began to hunt animals, who had already invented the stone ax and other hand tools. Entire species of mammals, birds and marine fauna are disappearing from the face of the Earth. The Neanderthal man could not withstand the harsh conditions either. Cro-Magnons were more resilient, successful in hunting, and it was their genetic material that should have survived.
Holocene era
The second half of the Quaternary period began twelve thousand years ago and continues to this day. It is characterized by relative warming and climate stabilization. The beginning of the era was marked by the mass extinction of animals, and it continued with the development of human civilization and its technological flourishing.
Changes in animal and plant composition throughout the era were insignificant. Mammoths finally became extinct, and some species of birds and marine mammals ceased to exist. About seventy years ago the general temperature of the earth increased. Scientists attribute this to the fact that human industrial activity causes global warming. In this regard, glaciers in North America and Eurasia have melted, and the Arctic ice cover is disintegrating.
glacial period
An ice age is a stage in the geological history of the planet that lasts several million years, during which there is a decrease in temperature and an increase in the number of continental glaciers. As a rule, glaciations alternate with warming periods. Now the Earth is in a period of relative temperature rise, but this does not mean that in half a millennium the situation cannot change dramatically.
At the end of the nineteenth century, geologist Kropotkin visited the Lena gold mines with an expedition and discovered signs of ancient glaciation there. He was so interested in the findings that he began large-scale international work in this direction. First of all, he visited Finland and Sweden, as he assumed that it was from there that the ice caps spread to Eastern Europe and Asia. Kropotkin's reports and his hypotheses regarding the modern Ice Age formed the basis of modern ideas about this time period.
History of the Earth
The ice age the Earth is currently in is far from the first in our history. Cooling of the climate has happened before. It was accompanied by significant changes in the relief of continents and their movement, and also influenced the species composition of flora and fauna. There could be gaps of hundreds of thousands or millions of years between glaciations. Each ice age is divided into glacial epochs or glacials, which during the period alternate with interglacials - interglacials.
There are four glacial eras in the history of the Earth:
Early Proterozoic.
Late Proterozoic.
Paleozoic.
Cenozoic.
Each of them lasted from 400 million to 2 billion years. This suggests that our ice age has not even reached its equator yet.
Cenozoic Ice Age
Animals of the Quaternary period were forced to grow additional fur or seek shelter from ice and snow. The climate on the planet has changed again.
The first epoch of the Quaternary period was characterized by cooling, and in the second there was relative warming, but even now, in the most extreme latitudes and at the poles, ice cover remains. It covers the Arctic, Antarctic and Greenland. The thickness of the ice varies from two thousand meters to five thousand.
The Pleistocene Ice Age is considered to be the strongest in the entire Cenozoic era, when the temperature dropped so much that three of the five oceans on the planet froze.
Chronology of Cenozoic glaciations
The glaciation of the Quaternary period began recently, if we consider this phenomenon in relation to the history of the Earth as a whole. It is possible to identify individual epochs during which the temperature dropped especially low.
- The end of the Eocene (38 million years ago) - glaciation of Antarctica.
- The entire Oligocene.
- Middle Miocene.
- Mid-Pliocene.
- Glacial Gilbert, freezing of the seas.
- Continental Pleistocene.
- Late Upper Pleistocene (about ten thousand years ago).
This was the last major period when, due to climate cooling, animals and humans had to adapt to new conditions in order to survive.
Paleozoic Ice Age
During the Paleozoic era, the Earth froze so much that ice caps reached as far south as Africa and South America, and also covered all of North America and Europe. Two glaciers almost converge along the equator. The peak is considered to be the moment when a three-kilometer layer of ice rose above the territory of northern and western Africa.
Scientists have discovered the remains and effects of glacial deposits in studies in Brazil, Africa (in Nigeria) and the mouth of the Amazon River. Thanks to radioisotope analysis, it was found that the age and chemical composition of these finds are the same. This means that it can be argued that the rock layers were formed as a result of one global process that affected several continents at once.
Planet Earth is still very young by cosmic standards. She is just beginning her journey in the Universe. It is unknown whether it will continue with us or whether humanity will simply become an insignificant episode in successive geological eras. If you look at the calendar, we have spent a negligible amount of time on this planet, and it is quite simple to destroy us with the help of another cold snap. People need to remember this and not exaggerate their role in the Earth's biological system.
The Quaternary period of the Cenozoic era was marked by large-scale glaciation, which had a huge impact on the development of life on the planet. As the glaciers advanced, the climatic barrier to life slowly moved south, and the lush vegetation of the Cenozoic also retreated south. During interglacial periods, it returned to its original territories. True, in some regions of the world the return of vegetation was often blocked by mountain ranges, which predetermined the extinction of many plants in the temperate zone. Some groups of animals, directly or indirectly dependent on certain types of vegetation, shared their fate.
Many representatives of the animal world have managed to adapt to the intensifying cold by acquiring thick fur. The Pleistocene era is characterized by a wide distribution of saber-toothed cats, marsupials and cave lions. In the Pleistocene, the first people appeared, and many large mammals, on the contrary, began to die out. Cold spells alternated with warming spells. During the Ice Age, three vegetation zones were clearly distinguished on the planet: tundra, steppe and taiga. They were located south of the advancing glaciers, in an area 200-320 km wide. Thus, repeated glaciations significantly devastated the flora of the planet, and the return of heat-loving plants from the south to the north was hampered by mountain ranges that acted as barriers to the spread of vegetation.
Nevertheless, during the warmest interglacial epochs of the Quaternary period, broad-leaved forests were widespread, dominated by oak, beech, linden, maple, ash, hornbeam, alder, walnut and hawthorn. During large-scale glaciation, water vapor condensed into the form of snow, but the melting of ice and snow annually produced less water than snowfall. The gradual accumulation of ice reserves on land contributed to a decrease in the level of the World Ocean. Therefore, in the Quaternary period, special land bridges arose between continental Europe and the British Isles, Asia and North America, the Amur region and Sakhalin, as well as between the Indochina Peninsula and the islands of the Sunda archipelago.
Animals and plants were exchanged across these land bridges. At the same time, it was the absence of a connecting link between Asia and Australia that preserved the life of cloacal and marsupials, which, even in the Tertiary period, were completely replaced by placental mammals on other continents of the planet. In the Quaternary period, various groups of mammals and, in particular, elephants were found. The largest of them lived in forests and had a shoulder height of over 4 m. In the Siberian tundra, the dominant position was occupied by the cold-loving mammoth Mammuthus primigenius, covered with thick and long reddish hair. During one of the ice ages, mammoths probably crossed the ice of the Bering Strait and settled throughout North America. Skeletons of heavy mastodons are often found in this region of the world today.
Prominent representatives of the fauna of that time were large woolly rhinoceroses, which during the glaciation era lived in the tundra next to mammoths. There was also a resettlement of horses, whose homeland is North America. Moving through Asia and Europe, they gradually settled throughout the world. It is noteworthy that in North America itself, horses became extinct by the end of the Pleistocene and returned there only with European conquerors. It is a pity that we were never able to see them, since these animals had a delightful appearance. Today, many fans of the world of fauna like to put pictures of animals in photo frames and hang them on their walls. But it’s better, of course, to insert photographs of loved ones there.
Numerous subspecies of wild horses inhabited the savannas of the European continent already at the beginning of the Quaternary period. Among the ruminant artiodactyls, one can distinguish a huge large-mouthed deer, the distance between the horns of which reached 3 m. Muskox, primitive bison and aurochs, the ancestors of modern domestic bulls, bred in large numbers. During the Quaternary period, our planet was also inhabited by numerous predators, among them we can note the huge cave bears Ursus spelaeus, the saber-toothed tigers Machairodus, whose long fangs resembled curved Turkish scimitars, and the cave lions Pamhera spelaea. During the glacial stage, the well-known hyenas, wolves, foxes, raccoons and wolverines already lived.
The Holocene epoch of the Quaternary period is the time of formation of the modern appearance of the fauna and flora of our planet. The diversity of living organisms today is noticeably less than in past geological eras. This may have been facilitated by the intense human impact on the environment. The appearance of the first apes in the Tertiary period ensured their further evolution in the Quaternary period of the Cenozoic. The appearance of the ancient ancestors of modern humans - Dryopithecus and Australopithecus - became possible. The next stage in the evolutionary ladder is the emergence of Homo habilis, the first representative of the genus Homo, and, finally, the species to which people living today belong - Homo sapiens. From that moment on, a completely new life began on the planet. In connection with the emergence of modern humans and the development of human civilization during the Quaternary period, it was proposed to call this stage of the Cenozoic era the Anthropocene. During the Holocene era, human civilization spread throughout the world. It gradually became the most important global factor that changed the biosphere of our planet. In particular, the advent of agriculture destroyed a large number of wild plant species in order to clear crop areas and pastures. In many cases, human activities were ill-considered and destructive to their environment.
Thus, the Quaternary period of the Cenozoic already took place with the participation and significant influence of man on the world around him. As the ice melted, human civilization settled into the territories liberated from under the glaciers. During this period, mastodons, mammoths, saber-tooth tigers and big-horned deer gradually became extinct. Again, ancient people who were actively involved in hunting played a significant role in this process. They exterminated the mammoth and woolly rhinoceros in Eurasia, as well as mastodons, horses and sea cows in America. Plowing of land, widespread hunting, burning of forests for pastures and trampling of grass by domestic animals have reduced the habitats of many steppe fauna. Human activity has contributed to the expansion of desert areas and the appearance of shifting sands.
The separation and movement of individual continents, as well as the establishment of climatic zoning, led to the separation of representatives of the biosphere into regions. The development of life in the Cenozoic provided the biological diversity on Earth that we can observe today. The result of the long evolution of life on our planet was the appearance of Homo sapiens at the end of the Quaternary period of the Cenozoic. With the end of prehistoric times, man began to create his own history. If approximately 4 thousand years ago there were about 50 million people living in the world, then already in the first half of the 19th century the number of people on the planet exceeded a billion. It is human activity that largely predetermined the species composition of the biosphere that currently exists. Man has also influenced the modern geographical distribution of living organisms on Earth.