NEOGEN PERIOD

The Neogene period (translated as newborn) is subdivided into two sections, the Miocene and Pliocene. During this period, Europe is connected with Asia. Two deep bays that emerged on the territory of Atlantis subsequently separated Europe from North America. Africa was fully formed, the formation of Asia continued.

On the site of the modern Bering Strait, an isthmus continues to exist, connecting Northeast Asia with North America. From time to time this isthmus was flooded with a shallow sea. The oceans have taken on a modern shape. Thanks to mountain-building movements, the Alps, Himalayas, Cordillera, East Asian ridges are formed. Depressions are formed at their foot, in which thick strata of sedimentary and volcanic rocks are deposited. Twice the sea flooded vast areas of the continents, depositing clay, sand, limestone, gypsum, and salt. At the end of the Neogene, most of the continents are freed from the sea. Climate neogene period was quite warm and humid, but somewhat cooler than the climate of the Paleogene period. At the end of the Neogene, it gradually acquires modern features.

It becomes similar to the modern and organic world... Primitive creodonts are being driven out by bears, hyenas, martens, dogs, badgers. Being more mobile and having a more complex organization, they adapted to various living conditions, intercepted prey from creodonts and marsupial predators, and sometimes fed on them.

Along with the species that, having slightly changed, have survived to our time, there were also species of predators that became extinct in the Neogene. These primarily include the saber-toothed tiger. It is so named because its upper canines were 15 cm long and slightly curved. They protruded from the closed mouth of the animal. In order to use them, the saber-toothed tiger had to open its mouth wide. Tigers hunted horses, gazelles, antelopes.

The descendants of the Paleogeonic Merikhippus, the Hipparions, already had such teeth as the modern horse. Their small side hooves did not touch the ground. The hooves on the middle toes became larger and wider. They kept the animals well on solid ground, gave them the opportunity to break the snow in order to extract food from under it, to protect themselves from predators.

Along with the North American horse development center, there was also a European one. However, in Europe, ancient horses died out at the beginning of the Oligocene, leaving no descendants. Most likely they were exterminated by numerous predators. In America, the ancient horses continued to evolve. Subsequently, they gave real horses, which penetrated Europe and Asia through the Bering Isthmus. In America, horses became extinct at the beginning of the Pleistocene, and large herds of modern mustangs, freely grazing on the American prairies, are distant descendants of horses brought by the Spanish colonialists. Thus, there was a kind of exchange of horses between the New World and the Old World.

Giant sloths - megateria (up to 8 m in length) lived in South America. Standing on their hind legs, they ate the leaves of the trees. Megatheria had a thick tail, a low skull with a small brain. Their front legs were much shorter than their hind legs. Being clumsy, they became easy prey for predators and therefore completely died out, leaving no descendants.

Changing climatic conditions led to the formation of vast steppes, which favored the development of ungulates. Numerous artiodactyls - antelopes, goats, bison, rams, gazelles, whose strong hooves were well adapted to fast running in the steppes, evolved from small hornless deer that lived on marshy soil. When so many artiodactyls bred that there was a shortage of food, some of them mastered new habitats: rocks, forest-steppe, deserts. From the humpless giraffe-shaped camels that lived in Africa, real camels originated, inhabiting the deserts and semi-deserts of Europe and Asia. The hump with nutrients allowed the camels to go without food and water for a long time.

The forests were inhabited by real deer, of which some species are still found today, while others, for example, mega-pilot, which were one and a half times larger than ordinary deer, completely died out.

Giraffes lived in the forest-steppe zones, hippos, pigs, tapirs lived near lakes and swamps. Rhinoceroses and anteaters lived in dense shrub thickets.

Among the proboscis, mastodons with straight long tusks and real elephants appear.

Lemurs, monkeys, great apes live in the trees. Some lemurs have adopted a terrestrial lifestyle. They moved on their hind legs. Reached 1.5 m in height. They ate mainly fruits and insects.

The dinornis, a giant bird living in New Zealand, reached 3.5 m in height. Dinornis's head and wings were small, and the beak was underdeveloped. He walked on the ground on long strong legs. Dinornis survived to the Quaternary period and, apparently, was exterminated by man.

It has adapted to new ecological niches that have opened up as a result of global cooling, and some mammals, birds and reptiles have evolved to truly impressive sizes. The Neogene is the second period (66 million years ago - to the present), which was preceded (66-23 million years ago) and replaced.

Neogene consisted of two eras:

• the Miocene era, or Miocene (23-5 million years ago);
• Pliocene epoch, or Pliocene (5-2.6 million years ago).

Climate and geography

As in the previous Paleogene, there was a trend towards global cooling during the Neogene, especially at higher latitudes (it is known that immediately after the end of the Neogene in the Pleistocene, the Earth underwent a series of ice ages mixed with warmer "interglacial eras"). Geographically, the Neogene was important for land bridges that opened between different continents: it was during the late Neogene that the North and South America were joined by the Central American isthmus; Africa was in direct contact with southern Europe through the dry Mediterranean basin; Eastern Eurasia and Western North America joined Siberia land bridges; the slow collision of the Indian subcontinent with Asia led to the formation of the Himalayan mountains.

Fauna of the Neogene

Mammals

Global climatic trends, combined with the spread of various grasses, made the Neogene period the golden age of the open prairie and.

These vast pastures have spurred the evolution of artiodactyls and equids, including prehistoric horses and (which originated in North America) as well as pigs, etc. During the later Neogene, the interconnections between Eurasia, Africa, and North and South America created a tangled web of species that led to the near extinction of the South American and Australian megafauna.

From a human point of view, the most important stage in the Neogene period was the continuing evolution of apes and hominids. During the Miocene era, a huge number of hominid species lived in Africa and Eurasia; during the subsequent Pliocene, most of these hominids (including direct ancestors modern people) were grouped in Africa. It was after the Neogene period, in the Pleistocene epoch, that the first human beings appeared (genus Homo) on the planet.

Birds

Some of the flying and flightless bird species of the Neogene were truly huge (for example, argentavis and osteodontornis exceeded 20 kg). The end of the Neogene meant the disappearance of most flightless birds of prey from South America and Australia. Bird evolution continued at a rapid pace, with most modern species well represented in the late Neogene.

Reptiles

For most of the Neogene period, giant crocodiles dominated, the size of which did not match the size of their Cretaceous ancestors.

This 20 Ma period also witnessed the continued evolution of prehistoric snakes and (especially) prehistoric turtles, the latter group of which began to reach truly impressive sizes by the beginning of the Pleistocene era.

Marine fauna

Although prehistoric whales began to evolve in the previous Paleogene period, they did not become exclusively marine creatures until the Neogene, which also indicated the continued evolution of the early pinnipeds (a family of mammals including seals and walruses), as well as prehistoric dolphins with which whales are closely related. Prehistoric sharks have retained their status at the top of the sea; for example, it already appeared at the end of the Paleogene and continued its dominance throughout the Neogene.

Plant world of the neogene

During the Neogene period, there were two main trends in plant life. First, falling global temperatures have spurred the growth of massive deciduous forests, which have replaced jungle and rainforests in the high northern and southern latitudes. Second, the worldwide spread of grasses goes hand in hand with the evolution of herbivorous mammals, culminating in today's horses, cows, sheep, deer and other grazing and ruminants.

Neogene period (Neogene)

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Neogene period is the second period of the Cenozoic era. Neogene originates from 23.3 million liters. BC, lasts 20 million years, and ends at the turn of the current Quaternary period 2.5 million years. n. During the Neogene period, the ancient Tethys Ocean ceased to exist forever.

Subdivisions of the Neogene period, its geography and climatic features

In accordance with the decision of the International Union of Geological Sciences of 2016, it was adopted subdivide the Neogene into two sections- The Miocene, which includes the Aquitanian, Burdigal, Langa, Serraval, Tortonian and Messinian stages, and the Pliocene, which is subdivided into the Zankl and Piacenza stages.

During the Neogene, the American continents moved further away from the emerging Eurasian continent, and a series of faults occurred in northeastern Africa, resulting in the Red Sea and the Arabian Peninsula. Such mountain ranges and massifs as the Alpine-Himalayan, Cordillera and Andes mountains were formed and took on modern outlines. Moving further and further towards present-day Europe, the African continent became the reason for the appearance of the Pyrenean, Alpine, Crimean and Carpathian mountain ranges, mountain systems of Iran and Turkey. The drifting continent of Hindustan, which was connected back in the Paleogene with the Middle Eastern part of the future Eurasian continent, continued to move in a northern direction, and therefore caused the growth of the Himalayan mountain range.

The South American continent, which continued to move farther and farther from the African continent, finally, in the Neogene, came across the ancient oceanic Pacific plate of Nazca, which became the reason for the formation of the current Andes mountain range. In this regard, mining transformation processes in these regions continue to this day. Also, to this day, tectonic processes that began in the Neogene are continuing in the zone of the East Asian belt. There is an alternating uplift, subsidence and change of island arcs, accompanied by strong seismic activity and volcanic eruptions. An accelerated process of accumulation of strata of debris is underway. Exactly at neogene era the Baikal graben was also formed, the continuation of the bend of which is the present-day Lake Baikal.

As a result of the further advancement of the African continent to the north oldest ocean The Tethys split into two huge sea basins. And if south basin, located on the territory of the modern Middle East, had a connection with the main World Ocean, then the northern one (it is usually called Paratethys) was in complete isolation, as a result of which its salinity increased more and more over time. By the end of the Neogene period, as a result of the beginning of global mountain-building processes, Paratethys split into a number of even smaller basins, as a result of which the future Black and Caspian Sea as well as the Mediterranean.

As a result of the fact that the main basin of the Mediterranean Sea was isolated from the outer oceans, due to the absence of water tributaries of about 5 million liters. n. this pool of the former Paratethys has almost completely evaporated. Thus, on the site of the present Mediterranean Sea during the Neogene there existed a drying up gigantic "bath", that is, a lowland filled with water only partially, and sinking many hundreds of meters relative to the level of the World Ocean.

At some point in time, in one of the places, the Gibraltar ridge, connecting Africa with Europe and separating the waters of the Atlantic from the Mediterranean Basin, was disturbed, as a result of which the Mediterranean basin began to fill with water again and after several decades the waters of the Mediterranean and Atlantic were completely equalized.

Neogene climate

Neogene climate was colder than the previous Paleogene. The global cooling that occurred on the border of the Paleogene and Neogene led to the emergence of stable ice belt sheets, and the ubiquitous climate became even more continental. In the north of the European continent, as in the vast areas of Siberia, there was a strip of temperate climate, changing to the subtropics and tropics to the south, but still having pronounced seasonal temperature changes, from which it follows that these areas were characterized by more or less severe winter times years, depending on their proximity to the equator. On the territory of Greenland, already at that time, the climate became arctic.

Throughout the entire Neogene, the climate became more severe, its continentality became even more pronounced, but for all that it was even much warmer than today, when, finally, the sharp cooling that occurred in the Pliocene (4.5 million years ago) did not brought him to a level close to the present. At the turn of the Pliocene and Pleistocene, ice shells covered from the south - most of Antarctica, from the north - vast areas of the northern sea, including Greenland, Patagonia, Iceland, Scandinavia and northern parts of Siberia.

Neogene sedimentation

Accumulations of sedimentary rocks of the Neogene occur throughout the territory of the present continents, as well as along the bottom of the World Ocean. Since mining and other geological activity in this period was extremely widespread across all continents, the main deposits of this time are volcanic rocks and products of other tectonic activity. Molasse and sandy-argillaceous formations also prevailed within the continents.

The greatest sedimentation in the oceans in comparison with the previous periods led to silicon and carbonate accumulations of different thickness in the territories of the equator and in the southern and northern latitudes. The accumulation of silicon in the Neogene period was even more powerful than in the Cretaceous period, and was due to the extraordinary dawn of diatoms. Terrigenous deposits took place closer to the continental areas.

Neogene animals

In the seas and oceans of the Neogene the simplest foraminifera and various radiolarians flourished. Bivalves and gastropods were numerous, and various crustaceans such as ostracods, for example, multiplied unusually. All kinds of bryozoans and echinoderms were diverse. In the extreme northern and southern territories, due to the cold snap, they disappeared, and in the central regions, corals blossomed even more and in a new way, most of which belonged to the six-rayed. The species of chordates - bony and cartilaginous fishes - multiplied more and more, and the number of marine whale-like, dolphin-like and seal-like mammals grew more and more.

Was extremely diverse fauna of land mammals of the Neogene period... In the Miocene, when the structure of the Paleogene landscape was still preserved in some places, the Anchiterian fauna developed on most continents. The typical representative of this fauna was the Anchiterium, a small mammal closest to today's ponies in size and structure. This was the ancient ancestor of modern horses. Neogene animals(Fig. 1) had three-toed limbs, and the variety of species of the Anchiterian fauna was amazing. It included the ancestors, as already mentioned, of horses, bears, rhinos, pigs, antelopes, deer, rodents, turtles, primates, etc. These were both representatives of the forest fauna and inhabitants of the steppes, savannas and woodlands. They were ecologically heterogeneous in accordance with the climatic conditions in which they were forced to live, so, for example, for hotter climatic zones, monkeys, gazelles, antelopes, mastodons, etc. were more typical. those who managed to acquire a plentiful wool cover.

Closer to the middle of the Neogene, in the vast territories of the Eurasian continent, North America and the African continent, a rapidly progressive hipparion fauna... It consisted of the first ancient horses, rhinos, proboscis, rodents, hippos, giraffes, deer, turtles, camels, saber-toothed tigers, hyenas, the first humanoid apes and other predators.

The main representatives of that fauna are rightfully considered to be hipparions, horses of small size, still having three-toed limbs, which replaced the Anchiterias, and living in the open steppe and savannah spaces. Due to the structure of their limbs, these animals of the Neogene excellently moved both in tall steppe grasses and along bog bumps.

Rice. 1 - Animals and plants of the Neogene

The predominant species in the hipparion fauna were those inhabiting the territories of steppe, forest-steppe, and other open landscapes. By the end of the Neogene, the hipparion fauna almost everywhere replaced the anchiterian fauna. Its composition has expanded even more due to the increase in the number of such species of savanna-light forest ancient animals as antelopes, various ostrich, camel-like, giraffes, and one-toed horses.

Since, back in the Paleogene, the connection between different continents was broken, and therefore representatives of the fauna could no longer migrate from continent to continent. This led to the manifestation of heterogeneous provincial differences. For example, the South American continent was abundantly inhabited by various ungulates, rodents and flat-nosed marsupial primates. This endemic fauna was also characteristic of the Australian continent.

Neogene plants

During the Neogene, under the influence of more severe climatic factors, the first taiga, forest-steppe, plain-steppe and mountain vegetation landscapes arose.

In the equatorial zones, hygrophilous plants predominated. These plants of the neogene period consisted of banana, ficus, palm, bamboo, laurel, tree-fern, evergreen oaks, etc. Closer to the northern and southern latitudes forests, due to lack of precipitation and seasonal changes climate, were replaced by savannas.

Closer to temperate latitudes, deciduous forests, consisting of evergreen tree forms, began to prevail. With the advent of the arid climate of the Neogene, vegetation of the Mediterranean type began to form here widely, which was expressed by the appearance among the total mass of laurel evergreen forests of such varieties of tree-like plants as boxwood, plane trees, various walnut, cypress, olive trees, as well as southern varieties of pine and cedar trees.

The relief of the area also played an important role in the distribution of plant species in the Neogene period. In the foothill areas there were yew, taxodium, and fern species. Above, the slopes of the mountains were covered with deciduous forests with a pronounced subtropical slope, then the slopes were covered with coniferous forests, consisting of pines, firs and spruces, later replaced by rare tundra shrubs and grassy growth, then turning into glaciers and year-round snow cover. This type of vegetation is called alpine zonation.

Closer to the polar regions, evergreen broadleaf forms disappear in the forests. In the woodlands, such holo- and angiosperms are beginning to dominate, such as sequoia, pine, spruce, willow, alder, beech, birch, maple, various walnut and chestnut. The arid regions of temperate latitudes were characterized by wide savanna and steppe areas. Forests here are more inclined towards river and coastal basins.

As a result of a sharp cooling that came at the end of the Neogene to replace the general short and insignificant warming, divisions into such zonal types of landscapes as taiga, forest-steppe, and tundra became pronounced. At the turn of the Neogene and the Quaternary period, vast areas of land were occupied by taiga forests, as scientists assume, as a result of a cold snap, descended from high-mountainous zones and settled over vast territories of the former taiga steppes.

Closer to the Quaternary period, the vast flat areas of the temperate zones were transformed into steppe ones. There were fewer and fewer forests, and more and more of the plains were covered with lush grassy steppe vegetation. In arid zones, savannahs and woodlands have been replaced by arid deserts and semi-deserts.

Mineral resources of the Neogene period

One of the significant minerals of the Neogene period is oil. The Neogene includes oil fields in the Caucasus, Sakhalin, Turkmenistan and Azerbaijan, as well as Romanian, Iraqi, Iranian, Arabian, Indonesian, Californian, Mexican, Colombian, Argentine and other oil basins.

There are also numerous ubiquitous deposits of combustible gases, brown coal, gypsum, sodium chloride and potassium salts. As a result of the intrusion of igneous rocks into the ridges of many mountain ranges, copper, arsenic, zinc, lead, molybdenum, antimony, mercury, bismuth, tungsten and other ores were soldered. Also Neogene include deposits of iron ores of the Kerch Peninsula and deposits of bauxite in the tropical zone on the islands of Guinea, Ghana, Suriname, Guyana, Jamaica, etc.

FAUNA

Significant changes have taken place in the composition of the fauna. The shelf zones were inhabited by bivalves and gastropods, corals, foraminifers, which reached a wide variety, and planktonic foraminifers and coccolithophorids in more remote areas.

In temperate and high latitudes, the composition of the marine fauna has changed. Corals and tropical forms of molluscs disappeared, and a huge number of radiolarians and especially diatoms appeared. Bony fishes, sea turtles and amphibians are widely developed.

The fauna of terrestrial vertebrates has reached a great variety. In the Miocene, when many landscapes retained the features of the Paleogene, the so-called Anchiterian fauna developed, which was named after its characteristic representative - Anchiteria. Anchiterium is a small animal, the size of a pony, and is one of the ancestors of horses with three-toed limbs. The Anchiterian fauna included many forms of horse ancestors, as well as rhinos, bears, deer, pigs, antelopes, turtles, rodents, and monkeys. This listing shows that the fauna included both forest and forest-steppe (savanna) forms. Ecological heterogeneity was observed depending on the landscape and climatic conditions. In the drier savannah regions, mastodons, gazelles, monkeys, antelopes, etc. were widespread.

In the middle of the Neogene, a rapidly progressing hipparion fauna appeared in Eurasia, North America, and Africa. It included ancient (hipparions) and real horses, rhinos, proboscis, antelopes, camels, deer, giraffes, hippos, rodents, turtles, great apes, hyenas, saber-toothed tigers and other predators.

The most characteristic representative of this fauna was the hipparion, a small horse with three-toed limbs, which replaced the Anchiterium. They lived in open steppe areas and the structure of their limbs indicates the ability to move both in tall grasses and in hummocky bogs ..

In the hipparion fauna, representatives of open and forest-steppe landscapes were predominant. At the end of the Neogene, the role of the hipparin fauna increased. In its composition, the importance of the savanna-steppe representatives of the animal world increased - antelopes, camels, giraffe, ostriches, and one-toed horse.

During the Cenozoic, communication between the individual continents was periodically interrupted. This hindered the migrations of terrestrial fauna and at the same time caused large provincial differences. For example, the fauna of South America was very peculiar in the Neogene. It consisted of marsupials, ungulates, rodents, flat-nosed monkeys. Since the Paleogene, the endemic fauna has developed in Australia as well.

FLORA

Under the influence of many factors in the Neogene, the organic world experienced rapid evolution. The animal and plant kingdom has acquired modern features. At this time, landscapes of taiga, forest-steppe, mountain and plain steppes first appeared.

In equatorial and tropical areas, humid forests or savannas were common. Vast areas were covered with peculiar forests, reminiscent of the modern rain forests of the Kalimantan lowlands. The tropical forests included ficuses, banana trees, bamboo palms, tree ferns, laurels, evergreen oaks, etc. Savannahs were located in areas with a strong moisture deficit and seasonal distribution of precipitation.

In temperate and high latitudes, the differentiation of the vegetation cover was more significant. Forest vegetation at the beginning of the Neogene was characterized by a variety and richness of species. Broad-leaved forests, in which the leading role was played by evergreen forms, enjoyed a fairly large development. Due to increased aridity, xerophilic elements appeared here, giving rise to the Mediterranean type of vegetation. This vegetation was characterized by the appearance in the composition of evergreen laurel forests of olives, walnuts, plane trees, boxwoods, cypresses, southern species of pines and cedars.

The relief played an important role in the distribution of vegetation. On the piedmont, abundantly swampy lowlands, there were thickets of nissos, taxodiums and ferns. Deciduous forests grew on the slopes of the mountains, in which the leading role belonged to subtropical forms, higher they were replaced by coniferous forests consisting of pine, fir, hemlock, spruce.

When moving towards the polar regions, evergreen and broad-leaved forms disappeared in the forests. Coniferous-deciduous forests were represented by a rather large range of gymnosperms and angiosperms from spruce, pine and sequoia to willow, alder, birch, beech, maple, walnut, chestnut. In the arid region of temperate latitudes, there were boreal analogs of savannas - steppes. Forest vegetation was found along river valleys and on the shores of lakes.

In connection with the cooling, which intensified at the end of the Neogene, new zonal types of landscape appeared and became widespread - taiga, forest-steppe and tundra.

Until now, the question of the place of origin of the taiga has not yet been finally resolved. Hypotheses of the subpolar origin of the taiga associate the formation of taiga components in the subpolar regions with its gradual spread to the south as the temperature falls. Another group of hypotheses suggests that the birthplace of taiga landscapes was Beringia, a land area that includes modern Chukotka and vast areas of the shelf seas of the northeast of the USSR. humidity. There is also another hypothesis, according to which the taiga arose as a result of vertical climatic zoning. The taiga vegetation first developed in the highlands, and then, as it were, “descended” onto the surrounding plains during a cold snap. At the end of the Neogene, taiga landscapes already occupied vast areas of Northern Eurasia and northern regions of North America.

At the turn of the Neogene and Quaternary, due to cooling and increased aridity in the forest formation, herbaceous plant communities of the steppe type were especially distinguished. In the Neogene, the process of the “great steppe of the plains” began. Initially, the steppes occupied limited areas and often alternated with forest-steppes. Steppe landscapes were formed within the inland plains of the temperate zone with a variable-humid type of climate. In the arid climate, semi-deserts and deserts have formed, mainly due to the reduction of savanna landscapes.

The very name of the Cenozoic means " new life". Yes, indeed, the Cenozoic era is a new life, from its beginning more similar to modernity. In the previous geological era - the Mesozoic - there were more differences.

The Cenozoic era began more than 60 million years ago and is divided into two periods: the earlier - the Tertiary and the later - the Quaternary, in which you and I live.

The Cenozoic era comes immediately after the Mesozoic. Specifically, it originates at the border of the Cretaceous and Paleogene, when the second largest catastrophic extinction of species occurred on Earth. This era is significant in the development of mammals, which replaced dinosaurs and other reptiles, almost one hundred percent extinct at the turn of these eras. In the process of development of mammals, a genus of primates emerged, from which man later evolved.

Periods of the Cenozoic era

• Paleogene (ancient). Duration - 42 million years. Epochs - Paleocene (66 million - 56 million years ago), Eocene (56 million - 34 million years ago), Oligocene (34 million - 23 million years ago)
• Neogen (new). Duration - 21 million years. Epochs - Miocene (23 million - 5 million years ago), Pliocene (5 million - 2.6 million years ago)
• Quaternary (Anthropogenic). It lasts now. Epochs - Pleistocene (2.6 million - 12 thousand years ago), Holocene (12 thousand years ago to the present).

During the Cenozoic era, the geographic outlines of the continents acquired the form that exists today. The North American continent was increasingly moving away from the remaining Laurasian, and now the Eurasian part of the global northern continent, and the South American segment was increasingly moving away from the African segment of southern Gondwana. Australia and Antarctica retreated more and more to the south, while the Indian segment was more and more "squeezed" to the north, until, finally, it joined the South Asian part of the future Eurasia, causing the rise of the Caucasian mainland, and also largely contributing to the rise from the water and the rest of the present part of the European continent.

Cenozoic climate constantly harsh. The cooling was not absolutely sharp, but still not all groups of animals and plant species had time to get used to it. It was during the Cenozoic that the upper and southern ice caps were formed in the region of the poles, and the climatic map of the earth acquired the zonation that we have today. It represents a pronounced equatorial belt along the earth's equator, and then, in order of distance to the poles, subequatorial, tropical, subtropical, temperate, and beyond the polar circles, respectively, the Arctic and Antarctic climatic zones.

Let us consider in more detail the periods of the Cenozoic era.

It begins with the great Cretaceous extinction, dated 66 million years ago. n. and lasted 43 million years to a mark of 23 million liters. n. It is at this period that the formation and dawn of mammals, as the main terrestrial species, falls. Throughout the entire period, the continents continued to diverge to the sides, the young Atlantic Ocean was formed, and the first serious cooling ended the Paleogene.

In accordance with the decision of the International Union of Geological Sciences, the Paleogene is usually subdivided into three departments- Paleocene (Danish, Zealand and Thanet), Eocene (Ypresian, Lutetian, Bartonian and Priabonian stages) and Oligocene (Rupel and Hattian stages).

During the Paleogene period, Gondwana and Laurasia continued to disintegrate into components, and if at the beginning of the Paleogene in some places animals could still migrate from one future global continents to others, then by the end of the Paleogene this was completely impossible. South America completely separated from the African continent, North America moved away from the European part of the future Eurasia, and in the north of Gondwana finally disintegrated into Australia, Antarctica and the Indian subcontinent, heading swiftly towards the South Asian part of Eurasia. For 40 million years, having covered a distance of more than 8 thousand km, he safely reached the upper continent and reunited with it. North and South American and continents diverged from Europe and Africa at a rate of 2 to 6 cm per year, and by the end of the Paleogene the width Atlantic Ocean already ranged from 1,000 to 2,500 km.

Throughout almost all Paleogene period During the Cenozoic era, the climate was warm and humid, although a constant trend towards a cooling was traced throughout its entire length. Average temperatures in the North Sea region were between 22-26 ° C. But by the end of the Paleogene it began to get colder and colder, and at the boundary with the Neogene, northern and southern ice caps were already formed. And if in the case of the northern sea these were separate areas of alternately forming and melting wandering ice, then in the case of Antarctica, a persistent ice sheet began to form here, which still exists today. The average annual temperature in the area of ​​the present polar circles has dropped to 5 ° C.

Paleogene animals

Since the beginning of the Paleogene animal world(Fig. 1), in which the main dominant species of the Cretaceous period disappeared, began to be widely populated by new species. The extinct ammonites, belemnites, rudists, inocerami, ichthyosaurs, plesiosaurs, dinosaurs and other groups of Mesozoic reptiles were replaced by mammals, which received a huge impetus in development with the beginning of the Paleogene.

New varieties of gastropods and bivalve molluscs have developed in the seas, and bony fishes have also advanced in their development. Nimmulites were especially common. It was from the limestones of these unicellular foraminifera that the ancient Pyramids of Egypt... Along with them, such calcareous unicellular algae like coccolithophorids. Also, a significant role was assigned to radiolarians, diatoms, and microscopic silicon flagella.

The bottom of the oceans and seas was covered with new sponges. Their spicules in some places accumulated and formed thickets of rather large-scale area, which subsequently developed into peculiar rocks - spongoliths. There were also numerous corals, mainly belonging to the scleractinians. There were both shallow and deep-water varieties. Almost all reef coral massifs of the current tropical belt originated in the middle of the Paleogene - Eocene.

Along with such bony fishes as rays and sharks, the first species of cetaceans, sirens and dolphin-like arose in the oceanic depths of the Paleogene period. They became the first mammals to decide to master the oceanic and marine aquatic environment.

From the amphibians after the Cretaceous cataclysm, only frogs, toads and a few giant salamanders remained. Some species of reptiles such as turtles, snakes, crocodiles and lizards also survived the chalk shock.

Rice. 1 - Animals of the Paleogene

Basic variety Paleogene mammals was small in size, and was closely associated with lacustrine-bog and forest vegetation. Closer to the middle of the Paleocene, a pronounced division of the bulk of mammalian species into such systematized groups as carnivorous, proboscis, ungulates, insectivorous, primate-like, rodents, etc., began to take place. But in view of the fact that most of them were in no hurry with development and remained rather primitive, many of them will die out already in the future Neogene.

The divergence of the continents led to the formation of their own specific fauna on the continents. So, for example, in Australia to this day, species of ancient marsupial mammals have survived, which became extinct on other continents at the time of the end of the Paleogene and the beginning of the Neogene. For quite a long time, throughout the entire Paleogene, marsupials, like edentulous and the first primates, existed on the South American continent.

In the tropical forests closer to the Miocene, the giant mammals Indricotherium rhinoceros developed, and the Indricotherium fauna replaced the brontoterian fauna. The Brontoterium fauna was named due to the fact that it was composed mainly of representatives of a variety of herbivorous equid-hoofed brontoteria, widespread in the middle of the Paleogene on all continents and geographic areas... Basically, they ate lush marsh vegetation and could stay in the water for a long time.

Also, the brontotherium ecological group consisted of ancient aminodont rhinoceroses, large pig-like eptelodonts, primitive artiodactyl anthracotherium, tapir-like, etc. The habitat of these animals was wet swampy places, river silted floodplains, drainless shallow lakes and wet lowlands. The indricotherium ecological group, which got its name from the ancient giant rhinoceros indricotherium, which was part of it, had a greater number of species and varieties. It included all the inhabitants of savannas, swampy forests and other marshy landscapes.

Savannahs at that time were inhabited by the already mentioned 8-meter indricotherium and all kinds of small rodents. Along with them, freshwater turtles also lived in light forests. More humid and swampy places were full of representatives of the brontotherium fauna - eptelodonts, aminodonts and anthracotheria - pig-like animals that vaguely resembled hippos. Ancient swamp rhinoceroses aminodonts bred in silted and swampy river floodplains, and ancient pig-like eptelodonts thrived in various coastal thickets.

Rice. 1 - Animals and plants of the Neogene

The predominant species in the hipparion fauna were those inhabiting the territories of steppe, forest-steppe, and other open landscapes. By the end of the Neogene, the hipparion fauna almost everywhere replaced the anchiterian fauna. Its composition has expanded even more due to the increase in the number of such species of savanna-light forest ancient animals as antelopes, various ostrich, camel-like, giraffes, and one-toed horses.

Since, back in the Paleogene, the connection between different continents was broken, and therefore representatives of the fauna could no longer migrate from continent to continent. This led to the manifestation of heterogeneous provincial differences. For example, the South American continent was abundantly inhabited by various ungulates, rodents and flat-nosed marsupial primates. This endemic fauna was also characteristic of the Australian continent.

Vegetation

Due to the cold snap and the fact that the climate began to acquire an increasingly continental color, areas of ancient steppes, savannas and woodlands widened, where the ancestors of modern buffalo, giraffe-like, deer-like, pigs and other mammals were grazing in large numbers, on which the ancient Cenozoic predators. It was at the end of the Neogene in the forests that the first ancestors of humanoid primates began to appear.

Despite the winters of the polar latitudes, tropical vegetation was still rampant in the equatorial belt of the earth. Broad-leaved woody plants were distinguished by the greatest variety. Consisting of them, as a rule, evergreen forests interspersed and bordered with savannas and shrubs of other open forests, later they gave a variety of modern Mediterranean flora, namely olive, plane trees, walnuts, boxwood, southern pine and cedar trees.

The northern forests were also diverse. There were no longer any evergreens here, but most of them grew and took root chestnut, redwood and other coniferous-broad-leaved and deciduous plants. Later, in connection with the second sharp cooling in the north, vast areas of tundra and forest-steppe were formed. The tundra has filled all the areas with the current temperate climate, and the places where tropical forests have recently grown violently have turned into deserts and semi-deserts.

Anthropogen (h quaternary period)

Quaternary period (anthropogen) originates from 2.6 million liters. n. and continues to this day. During the time that this time period lasts, three main things have happened:

• the planet entered a new ice age, during which sharp cold snaps alternated with warming;
• the continents assumed their final present outlines, the modern relief was formed;
• Homo sapiens appeared on the planet.

Subdivisions of the anthropogen, geological changes, climate

Almost the entire length of the anthropogen is occupied by the Pleistocene division, which, according to international stratigraphic standards, is usually divided into the Gelazian, Calabrian, Middle and Upper stages, and the Holocene, which originates a little more than 11 thousand years ago. n. and continuing to this day.

Basically, the continents in their present form were formed long before the beginning of the Quaternary period, but it was during this period of time that many young mountain ranges acquired their present appearance. The coastline of the continents took on the current outlines, and due to the alternately advancing and retreating glaciers, the extreme northern continental archipelagos were formed, such as the Canadian, Spitsbergen Islands, Iceland, New earth etc. In the course of alternating glaciations at some intervals of time, the level of the World Ocean dropped to 100 meters.

Retreating, the giant anthropogenic glaciers left a trail of deep moraines in their wake. During the periods of maximum glaciation, the total area of ​​glaciers exceeded the current ones by more than three times. Thus, it can be said that large parts of North America, Europe and present-day Russia were buried under ice strata.

It is worth saying that the current ice age is not the first in the history of the earth. For several billion years, the first historical ice age lasted, beginning with 1.5 billion years. n. in the early Proterozoic. After prolonged heat, a 270-million-year cold snap hit the planet again. It happened 900 million liters. n. in the late Proterozoic. Then another significant icing took place, lasting over 230 million liters. n. in the Paleozoic (460 - 230 million years ago). And now the planet is experiencing another cold snap, the beginning of which is usually attributed to 65 million years ago. It gradually gained strength and it is not yet known whether the Cenozoic global ice age survived its apogee of low temperatures.

Rice. 1 - Anthropogen (Quaternary)

During the current ice age, there has been a great many warming and cooling, and according to scientists, in this period of time the Earth is experiencing a warming stage. According to their calculations, the last cold snap was replaced by a warming from 15 to 10 thousand years ago. During the strongest glaciations of the Pleistocene, the line of glaciers dropped from 1500 to 1700 km south of the present line.

Anthropogen climate was subject to repeated fluctuations. In those days when the glaciers were advancing climatic zones narrowed and retreated closer to the equator, and, conversely, during periods of warming and massive melting of glaciers, the temperate zone spread to the northernmost continental margins and, as a result, other climatic zones also widened.

Climate

IN anthropogenic period unexpected warming alternated with equally sharp cold snaps. The boundaries of the anthropogenic glacial zone sometimes reached 40 ° northern latitudes. North America, Europe up to the Alps, the Scandinavian Peninsula, the Northern Urals, and Eastern Siberia were located under the northern ice cap. Also, due to glaciation and melting of ice caps, there was a decline, then a re-advance of the sea on land. The periods between glaciations were accompanied by marine regression and a mild climate. At the moment, there is one of such intervals, which should be replaced no later than in the next 1000 years by the next stage of icing. It will last for about 20 thousand years, until it is again replaced by another period of warming. It is worth noting here that the alternation of intervals can occur much faster, or it can be completely violated due to interference in the earth's natural processes of man. It is likely that the Cenozoic era could end with a global ecological catastrophy akin to the one that caused the death of many species in the Permian and Cretaceous.

Quaternary animals

Among invertebrates in the Pleistocene of the Quaternary period, all kinds of snails and other land mollusks developed extraordinarily. The underwater world was in many ways similar to the previous Neogene. The world of insects also began to acquire a resemblance to the present, but the world of mammals was subject to the most interesting metamorphoses.

Since the beginning of the anthropogen, varieties of elephants have become widespread. At the beginning of the Pleistocene, they inhabited vast territories of the Eurasian continent. Some of their species reached a height of 4 m at the withers. Increasingly in northern parts continents began to appear species of elephants covered with long hair. By the middle of the Pleistocene, mammoths were already the most common and most widespread representatives of the northern tundra latitudes. Having migrated across the ice of the Bering Strait in one of the next cold snap segments to Alaska, mammoths have multiplied throughout the entire North American continent. Mammoths are believed to have evolved from the trogontery elephants, on the border of the Neogene and Pleistocene, widespread in the steppe latitudes.