Cenozoic era: periods, climate. Life in the Cenozoic Era
Currently, the Cenozoic era continues on Earth. This stage of development of our planet is relatively short, if we compare it with previous ones, for example, the Proterozoic or Archean. While it is only 65.5 million years.
The geological processes that took place throughout the Cenozoic formed the modern appearance of the oceans and continents. The climate gradually changed and, as a result, the plant world in one or another part of the planet. The previous era - the Mesozoic - ended with the so-called Cretaceous catastrophe, which caused the extinction of many species of animals. The beginning of a new era was marked by the fact that empty ecological niches began to be filled again. The development of life in the Cenozoic era occurred rapidly both on land and in water and in the air. The dominant position occupied by mammals. Finally, the ancestors of man appeared. People turned out to be very “promising” creatures: despite repeated climate change, they not only survived, but also evolved, settling throughout the planet.Over time, human activity has become another factor in transforming Earth.
Cenozoic era: periods
Previously, Cenozoic (“the era of a new life”) was usually divided into two main periods: tertiary and quaternary. Now another classification is in progress. The very first stage of the Cenozoic is Paleogene (“ancient formation”). It began about 65.5 million years ago and lasted 42 million years. Paleogene is divided into three subperiods (Paleocene, Eocene, and Oligocene).
The next stage is Neogene (“new education”). This era began 23 million years ago, and its duration was approximately 21 million years. The Neogene period is divided into the Miocene and Pliocene. It is important to note that the end of the Pliocene dates back to the emergence of human ancestors (although at that time they didn’t even resemble modern people). Somewhere 2-1.8 million years ago, the anthropogenic, or quaternary, period began. He continues to this day. Throughout the anthropogenic, human development took place (and is happening). The sub-periods of this stage are the Pleistocene (the epoch of glaciation) and the Holocene (the post-glacial epoch).
Climatic conditions of the Paleogene
A long period of the Paleogene opens the Cenozoic era.ClimatePaleocene and Eocene was mild. In the equatorial area, the average temperature reached 28 ° C. In the North Sea region, the temperature was not much lower (22–26 ° C).
On the territory of Svalbard and Greenland, evidence was found that plants characteristic of modern subtropics felt quite comfortable there. Traces of subtropical vegetation found in Antarctica. There were no glaciers or icebergs in the Eocene. On Earth, there were areas that did not experience a lack of moisture, regions with a variable-humid climate and arid regions.
In the period of the Oligocene sharply colder. At the poles, the average temperature dropped to 5 ° C. The formation of glaciers began, which later formed the Antarctic ice sheet.
The Cenozoic era is a time of universal domination of the angiosperms and gymnosperms (conifers). The latter grew only in high latitudes. At the equator, rain forests dominated, the basis of which was palm trees, rubber plants and various sandalwood trees. The farther from the sea, the drier the climate became: in the depths of the continents savanna and light forest spread.
In the middle latitudes, moisture-loving tropical plants and plants of a temperate climate (tree ferns, bread trees, sandalwood, banana trees) were common. Closer to high latitudes, the species composition became quite different. Typical flora of subtropics is characteristic of these places: myrtle, chestnut, laurel, cypress, oak, thuja, sequoia, araucaria. The plant life in the Cenozoic era (in particular, in the era of the Paleogene) flourished even beyond the Arctic Circle: in the Arctic, Northern Europe and America, the predominance of coniferous-deciduous deciduous forests was noted. But met here and subtropical plants listed above. The polar night was not an obstacle to their growth and development.
The Cenozoic era gave a unique chance to the fauna. The fauna has changed dramatically: primitive small mammals that live mainly in forests and in swamps have replaced dinosaurs. Reptiles and amphibians became less. Various proboscid animals prevailed, indictomeric (similar to rhinoceroses), tapiro and pig-like.
As a rule, many of them were adapted to spend some time in the water.During the Paleogene period, the ancestors of horses, various rodents, later - predators (creodonts) also appear. Toothless birds nestle on treetops, predatory diatrims live in savannas - birds that cannot fly.
Great variety of insects. As for the marine fauna, then there is a flowering of cephalopods and bivalves, corals; primitive crayfish, cetaceans appear. The ocean at this time belongs to the bony fish.
The Cenozoic era continues. The climate in the Neogene epoch remains relatively warm and rather humid. But the cooling that began in the Oligocene makes its own adjustments: the glaciers no longer melt, the humidity drops, the continental climate increases. By the end of the Neogene, the zonality approached the modern (the same can be said about the outlines of the oceans and continents, as well as the relief of the earth's surface). Pliocene marked the beginning of the next cold snap.
Neogene, Cenozoic era: plants
At the equator and in tropical zones, either savannah or wet forests still prevail. The temperate and high latitudes could boast the greatest diversity of the plant world: broad-leaved forests, mostly evergreen, were common here.As the air became drier, new species emerged, of which the modern Mediterranean flora gradually developed (olive, platan, walnut, boxwood, southern pine and cedar). In the north, evergreens no longer survived. But coniferous-deciduous forests showed a wealth of species - from redwood to chestnut. At the end of the Neogene, such forms of the landscape as taiga, tundra and forest-steppe appeared. This again was due to cooling. North America and North Eurasia have become taiga regions. Steppe was formed in temperate latitudes with arid climate. Where there were savanna earlier, semi-deserts and deserts appeared.
It would seem that the Cenozoic era is not so long (in comparison with the others): the flora and fauna, however, managed to change greatly from the beginning of the Paleogene. Placental became the dominant mammals. Initially, the development of anchiterian, and then - hipparion fauna. Both are named after characteristic representatives. Anchitherium is the ancestor of a horse, a small animal with three fingers on each limb. Hipparion is, in fact, a horse, but still three-fingered.No need to think that only relatives of horses and just ungulates (deer, giraffes, camels, pigs) belonged to these faunas. In fact, among their representatives were predators (hyenas, lions), rodents, and even ostriches: life in the Cenozoic era was characterized by fantastic diversity.
The spread of these animals contributed to an increase in the area of savannas and steppes.
At the end of the Neogene in the forests appeared the ancestors of man.
This period is characterized by alternation of glaciations and warming. When the glaciers were advancing, their lower boundaries reached 40 degrees north latitude. The largest glaciers of that time were concentrated in Scandinavia, the Alps, North America, Eastern Siberia, the Subpolar and Northern Urals.
In parallel with the glaciations, an offensive of the sea occurred on land, although not as powerful as in the Paleogene. Interglacial periods were characterized by a mild climate and regression (drainage of the seas). Now is the next interglacial period, which should end no later than 1000 years. After it, another glaciation will occur, which will last about 20 thousand years.But it is not known whether this will actually happen, since human intervention in natural processes provoked a warming of the climate. It’s time to wonder if the Cenozoic era will end.global environmental catastrophe?
Flora and fauna of anthropogen
The onset of the glaciers forced the thermophilic plants to move to the south. True, this prevented the mountain ranges. As a result, many species have not survived to our days. During the glaciations, there were three main types of landscapes: taiga, tundra and forest-steppe with their characteristic plants. Tropical and subtropical belts strongly narrowed and shifted, but still remained. In the interglacial periods on Earth dominated by deciduous forests.
As for the fauna, the primacy still belonged (and belongs) to mammals. Massive, woolly animals (mammoths, woolly rhinos, megaloceros) became the hallmark of glacial eras. Along with them there were bears, wolves, deer, lynxes. All animals as a result of cooling and warming were forced to migrate. Primitive and maladjusted died out.
Primates continued their development.Improving the hunting skills of human ancestors can explain the extinction of a number of game animals: giant sloths, horses of North America, mammoths.
It is not known when the Cenozoic era will end, the periods of which we have examined above. Sixty-five million years by the standards of the Universe is quite a bit. However, during this time, continents, oceans and mountain ranges have been formed. Many species of plants and animals became extinct or evolved under the pressure of circumstances. Mammals took the place of dinosaurs. And the most promising of mammals turned out to be man, and the last period of Cenozoic, the anthropogen, is associated mainly with human activity. It is possible that it depends on us how and when the Cenozoic era will end - the most dynamic and short of the epochal periods.