4th period of the Paleozoic. Paleozoic era: periods, climate. Flora and fauna of the Paleozoic era. Periods of the Paleozoic era
Eon - Phanerozoic Beginning of the era 541 million years ago End of the era 298.9 million years ago Duration 242.1 million years ago
Periods Paleozoic Cambrian Ordovician Silurian Devonian Carboniferous Permian (D) (С) (P) (S) (О) (€) 541485.4443.4419.2358.9298.9 Duration (million years) 55.6 42 42 24, 2 60, 3 60
TECTONICS The Cambrian began about 542 million years ago, ended 488 million years ago, the Cambrian continued for about 54 million years. 180°, were united into a single supercontinent called Gondwana.
Ordovician Ordovician, the second from the bottom system of the Paleozoic group, corresponding to the second period Paleozoic era geological history Earth. It is underlain by the Cambrian and overlain by the Silurian systems. It began 485.4 ± 1.9 million years ago and ended 443.4 ± 1.5 million years ago. It continued in this way for about 42 million years. In the Ordovician, Gondwana, moving south, entered the region of the South Geographic Pole (now it is the northwestern part of Africa). There was an upthrust of the ocean lithospheric plate Proto-Farallon (and probably Proto. Pacific Plate) beneath the northern margin of the Gondwana Plate. The reduction of the Proto-Atlantic basin, located between the Baltic Shield, on the one hand, and the single Canadian-Grenland Shield, on the other hand, began, as well as the reduction of the ocean space. During the entire Ordovician, there is a reduction in oceanic spaces and the closure of the marginal seas between the continental fragments: Siberian, Proto-Kazakhstan and China.
Silurian period (Silurian, also Silurian system) - geological period, the third period of the Paleozoic, after the Ordovician, before the Devonian. It began 443.4 ± 1.5 million years ago and ended 419.2 ± 3.2 million years ago. It continued in this way for about 24 million years. resulting relief earth's surface at the end of the Silurian period, it became elevated and contrasting, especially on the continents located in the northern hemisphere. the Caledonian folding continued.
Devon Devo n (Devonian period, Devonian system) - the fourth geological period of the Paleozoic era. It began 419.2 ± 3.2 Ma ago and ended 358.9 ± 0.4 Ma ago. It continued in this way for about 60 million years. In the Early Devonian, the Proto-Atlantic Basin closes and the Euro is formed. The American mainland, as a result of the collision Pro. European mainland with Pro. North American in the area of \u200b\u200bpresent-day Scandinavia and Western Greenland. In the Devonian, the displacement of Gondwana continues, as a result, the South Pole is in southern region modern Africa, and possibly present-day South America.
The Carboniferous Kamennou Goal period, abbreviated Carboniferous (C) is the penultimate (fifth) geological period of the Paleozoic era. It began 358.9 ± 0.4 Ma ago and ended 298.9 ± 0.15 Ma ago. It continued in this way for about 60 million years. In the Middle Carboniferous, Gondwana and Euro-America collided. As a result, a new supercontinent Pangea was formed. In the Late Carboniferous - Early Permian, the Euro collided. The American mainland with the Siberian, and the Siberian mainland with the Kazakhstan continent.
Perm Permian period (Perm) - the last geological period of the Paleozoic era. Started 298.9 ± 0.15 Ma ago, ended 252.17 ± 0.06 Ma ago. It continued in this way for about 47 million years. The sediments of this period are underlain by Carboniferous and overlain by Triassic. By the end of the Paleozoic, in the Permian period, Pangea stretched from south pole to the North.
Cambrian On land there was intense prosia, a large number of rainfall was washed into the sea. The oxygen content in the atmosphere gradually increased. Toward the end of the period, glaciation began, which led to a decrease in sea level.
Ordovician Large land masses concentrated closer to the equator. Throughout the period, the land masses moved further and further south. The old Cambrian ice sheets melted and sea levels rose. Most of the land was concentrated in warm latitudes. At the end of the period, a new glaciation began.
Silurian Period of violent volcanic activity and intense mountain building. Started with the Ice Age. As the ice melted, sea levels rose and the climate became milder.
Devonian Rivers carried mountains of sediment into the sea. Vast swampy deltas formed. Sea levels dropped towards the end of the period. The climate warmed over time and became harsher with alternating periods of heavy rains and severe drought. Vast areas of the continents became waterless.
Carboniferous In the Early Carboniferous, small coastal seas and swamps spread over vast areas, and almost tropical climate. Huge forests with lush vegetation have significantly increased the oxygen content in the atmosphere. Subsequently, it became colder, and at least two major glaciations occurred on Earth.
The Permian Period began with a glaciation that caused sea levels to drop. As Gondswana moved north, the land warmed up and the ice gradually melted. It became very hot and dry in Laurasia, vast deserts spread across it.
The Cambrian Animal Kingdom During the grandiose evolutionary explosion, most modern types animals, including microscopic foraminifera, sponges, starfish, sea urchins, sea lilies and various worms. In the tropics, archaeocyates. erected huge reef structures. The first hard-covered animals appeared; trilobites and brachiopods dominated the seas. The first chordates appeared. Later appeared cephalopods and primitive fish.
Ordovician Animal Life: A sharp increase in the number of filter-feeding animals, including bryozoans (sea mats), sea lilies, brachiopods, bivalves and graptolites, which flourished just in the Ordovician. Archaeocyates have already died out, but the baton of reef building was picked up from them by stromatoporoids and the first corals. The number of nautiloids and jawless armored fish increased.
Vegetable world: There were different kinds algae. In the Late Ordovician, the first true land plants.
Silurian Animal Kingdom: Nautiloids, brachiopods, trilobites and echinoderms thrive in the seas. The first jawed acanthode fish appeared. Scorpions, centipedes, and possibly eurypterids have begun to make their way onto land. The formation of the main classes of invertebrate organisms, the first primitive vertebrates (jawless and fish) appeared.
Devonian Animal Kingdom: Rapid evolution of fish, including sharks and rays, lobe-finned and ray-finned fish. The land was invaded by many arthropods, including ticks, spiders and primitive wingless insects. The first amphibians appeared in the late Devonian.
Flora: Plants managed to move away from the water's edge and soon vast areas of land were overgrown with dense primeval forests. The number of diverse vascular plants has increased. Spore-bearing lycophytes (mosquitoes) and horsetails appeared, some of them developed into real trees 38 m high.
Carboniferous Animals: Ammonites appeared in the seas, the number of brachiopods increased. Rugoses, graptolites, trilobites, as well as some bryozoans, sea lilies and mollusks have become extinct. This was the age of amphibians, as well as insects - grasshoppers, cockroaches, silverfish, termites, beetles and giant dragonflies. The first reptiles appeared.
Flora: River deltas and banks of vast swamps are overgrown with dense forests of giant club mosses, horsetails, tree ferns and seed plants up to 45 m high. The undecomposed remains of this vegetation eventually turned into coal.
Permian Animal World: Rapidly Evolved bivalves. Ammonites abounded in the seas. Amphibians predominated in fresh water bodies. Appeared and aquatic reptiles, including mesosaurs. During the great extinction, over 50% of animal families disappeared. On land, the reptiles took over the amphibians.
Flora: On the southern land masses, forests of large seed ferns, lossopteris, have spread. The first conifers appeared, quickly populating the inland regions and highlands. Among terrestrial plants, arthropod ferns and gymnosperms predominated.
Conclusion: The Paleozoic era (Greek "palaios" - ancient, "zoe" - life) - the era ancient life Its age is 570 million years. Divided into 6 periods (Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian) The plant world developed from algae to the first seed plants (seed ferns). The animal world developed from primitive marine skullless chordates to terrestrial reptiles. In the Silurian period, the first inhabitants of the land appeared - psilophyte plants and invertebrate arachnids. They were the first animals to breathe atmospheric oxygen.
The beginning of the Paleozoic era is marked by the Cambrian explosion. During this relatively rapid period of evolution and development of species, many new and more complex organisms appeared than the Earth has ever seen. During the Cambrian, many ancestors of today's species appeared, including and.
The Paleozoic era is divided into six main periods, as shown below:
Cambrian period, or Cambrian (542 - 485 million years ago)
The first period of the Paleozoic era is known as. Some species of the ancestors of living animals first appeared during the Cambrian explosion, in the early Cambrian. Despite the fact that this "explosion" took millions of years, this is a relatively short period of time compared to the entire history of the Earth. At that time, there were several continents that were different from those that exist today. All the land that made up the continents was concentrated in the southern hemisphere of the Earth. This allowed the oceans to occupy vast territories, and marine life flourish and differentiate at a rapid pace. Rapid speciation has resulted in a level of genetic diversity in species that has never before existed in the history of life on our planet.
Almost all life in the Cambrian period was concentrated in the ocean. If there was any life on land, it was most likely single-celled microorganisms. In Canada, Greenland and China, scientists have discovered fossils from this time period, among which many large shrimp and crab-like carnivores have been identified.
Ordovician period, or Ordovician (485 - 444 million years ago)
After the Cambrian period came. This second period of the Paleozoic era lasted about 41 million years and increasingly diversified aquatic life. large predators, similar to, hunted small animals at the bottom of the ocean. Many changes took place during the Ordovician environment. Glaciers began to move to the continents, and ocean levels dropped significantly. The combination of temperature change and the loss of ocean water resulted in , which marked the end of the period. About 75% of all living things died out at that time.
Silurian period, or Silurian (444 - 419 million years ago)
After the mass extinction at the end of the Ordovician period, the diversity of life on Earth was supposed to come back. One of the major changes in the layout of the planet's landmasses was that the continents began to connect. This has created an even more continuous space in the oceans for development and diversification. Animals could swim and feed close to the surface, something that had not happened before in the history of life on Earth.
A lot has spread different types jawless fish and even the first ray-finned fish appeared. While land life was still absent (with the exception of single cell bacteria), species diversity began to recover. Atmospheric oxygen levels were much the same as they are today, so by the end of the Silurian, some species of vascular plants were seen on the continents, as well as the first arthropods.
Devonian period, or Devonian (419 - 359 million years ago)
Diversification has been rapid and widespread over the course of . Ground flora became more common and included ferns, mosses, and even seed plants. Root systems These early terrestrial plants helped rid the soil of rocks, providing more opportunities for plants to take root and grow on land. Many insects also appeared during the Devonian period. Toward the end of the Devonian, amphibians moved to land. As the continents connected, this allowed new land animals to spread easily into different ecological niches.
Meanwhile, in the oceans, jawless fish adapted to the new environment by developing jaws and scales like modern fish. Unfortunately, the Devonian period ended when large asteroids. The impact of these meteorites is believed to have caused a mass extinction that wiped out almost 75% of aquatic life species.
Carboniferous period, or Carboniferous (359 - 299 million years ago)
Again, this was a time when species diversity had to recover from the previous mass extinction. Since the mass extinction of the Devonian period was mostly limited to the oceans, land plants and animals continued to thrive and develop at a rapid pace. further adapted and diverged from early reptile ancestors. The continents were still joined together, and the most southern regions were again covered by glaciers. However, there were also tropical climatic conditions, thanks to which a large lush vegetation developed, evolving into many unique species. These were marsh plants that formed the coal used in modern times for fuel and other purposes.
As for life in the oceans, the pace of evolution seems to have been noticeably slower than before. Species that managed to survive the last mass extinction continued to evolve and form new similar species.
Permian period, or Permian (299 - 252 million years ago)
Finally, all the continents on Earth came together completely to form the supercontinent known as Pangea. At the beginning of this period, life continued to evolve and new species emerged. Reptiles were fully formed, splitting off from the evolutionary branch that eventually gave rise to mammals in mesozoic era. Fish from the salty waters of the oceans adapted to life in freshwater bodies throughout the continent of Pangea, which led to the emergence of freshwater animals. Unfortunately, this time of species diversity has come to an end, partly due to the many volcanic explosions that have depleted oxygen and affected the planet's climate, blocking sunlight, which led to the emergence of many glaciers. All this led to the largest mass extinction in the history of the Earth. It is believed that at the end of the Paleozoic era, almost 96% of all species were destroyed.
The Paleozoic era covers a huge time span of approximately 542 - 250 million years ago. Its first period was "Cambrian", which lasted about 50-70 (according to various estimates) million years, the second - "Ordovician", the third - "Silur", the fourth - the sixth, respectively, "Devon", "Carbon", "Perm" . At the beginning of the Cambrian, the vegetation of our planet was represented mainly by red and blue-green algae. This species is more similar in structure to bacteria, since it does not have a nucleus in the cell (real algae have this nucleus, therefore they are eukaryotes). The Paleozoic era, the climate of which at the beginning was temperate, with the predominance of the seas and low land, contributed to the prosperity of algae.
It is believed that they created the atmosphere
They are descended from worms
The Paleozoic era was the time of the birth and ancestors of modern cephalopods - squid, octopus, cuttlefish. Then they were small creatures with horny shells, through which a siphon passed, enabling the animal to fill parts of the shells with water or gases, changing its buoyancy. Scientists believe that ancient cephalopods and mollusks descended from ancient worms, the remains of which are few, as they consisted mainly of soft tissues.
The Paleozoic era, the plants and animals of which either replaced each other or coexisted side by side for millions of years, also gave life to cystoids. These creatures, attached to the bottom with a limestone cup, already had tentacle arms that pressed the particles of food floating past to the feeding organs of the cystoids. That is, the animal has moved from passive waiting, as in archaeocyaths, to the extraction of food. Scientists also attributed the discovered fish-like creature, which had a spine (chord), to the early Paleozoic.
Three-meter rakoscorpions ... with a poisonous sting
But primitive fish developed in the Silurian and Ordovician, where they were jawless, shell-covered creatures with organs that emit electrical discharges for protection. During the same period, one can find giant nautiloids with three-meter shells and no less large crustacean scorpions, up to three meters long.
The Paleozoic era was rich in climate change. So, in the late Ordovician it became significantly colder, then it warmed up again, in the early Devonian the sea receded significantly, active volcanic mountain building took place. But it is the Devonian that is called the era of fish, since cartilaginous fish- sharks, rays, lobe-finned fish, which had nasal openings for breathing air from the atmosphere and could use fins for walking. They are considered the ancestors of amphibians.
The very first steceophages (amphibious giant snakes and lizards) left their traces in the late Paleozoic, where they coexisted with cotilomeres - ancient reptiles that were both predators and insectivorous and herbivorous animals. The Paleozoic era, during which the table of development of life forms is presented above, has left many mysteries that scientists have yet to unravel.
Paleozoic era: Cambrian period (from 540 to 488 million years ago)
This period began with an astonishing evolutionary explosion, during which representatives of most of the major groups of animals known for the first time appeared on Earth. modern science. The boundary between the Precambrian and Cambrian runs along rocks, which suddenly reveals a surprising variety of animal fossils with mineral skeletons - the result of the "Cambrian explosion" of life forms.
In the Cambrian period, large areas of land were occupied by water, and the first supercontinent Pangea was divided into two continents - northern (Laurasia) and southern (Gondwana). Significant erosion of the land is observed, volcanic activity was very intense, the continents either fell or rose, resulting in the formation of shoals and shallow seas, which sometimes dried up for several million years, and then were again filled with water. At this time, the oldest mountains appeared in Western Europe(Scandinavian) and in Central Asia(Sayans).
All animals and plants lived in the sea, however, the intertidal zone was already inhabited by microscopic algae, which formed terrestrial algal crusts. It is believed that the first lichens and terrestrial fungi began to appear at this time. The fauna of that time, first discovered in 1909 in the mountains of Canada by C. Walcott, was represented mainly by benthic organisms, such as archaeocyates (analogues of corals), sponges, various echinoderms (starfish, sea urchins, sea cucumbers, etc.), worms, arthropods (various trilobites, horseshoe crabs). The latter were the most common form of living creatures of that time (approximately 60% of all animal species were trilobites, which consisted of three parts - head, body and tail). All of them died out by the end of the Permian period, of horseshoe crabs, only representatives of one family have survived to this day. Approximately 30% of the Cambrian species were brachiopods - marine animals with a bivalve shell, similar to molluscs. From trilobites that switched to predation, crustaceans up to 2 m long appeared. At the end of the Cambrian period, cephalopods appeared, including the nautilus genus that has survived to this day, and from echinoderms, primitive chordates (tunicates and non-cranial). The appearance of a chord, which gave the body rigidity, was important event in the history of the development of life.
Paleozoic era: Ordovician and Silurian periods (from 488 to 416 million years ago)
At the beginning of the Ordovician period, most of the southern hemisphere was still occupied by the great continent of Gondwana, while other large land masses were concentrated closer to the equator. Europe and North America (Laurentia) were pushed further apart by the expanding Iapetus Ocean. First, this ocean reached a width of about 2000 km, then began to narrow again as the land masses that make up Europe, North America and Greenland began to gradually converge until they finally merged into a single whole. During the Silurian period, Siberia "sailed" to Europe (the Kazakh uplands formed), Africa collided with southern part North America, and as a result, a new giant supercontinent Laurasia was born.
After the Cambrian, evolution was characterized not by the emergence of completely new types of animals, but by the development of existing ones. In the Ordovician, the most severe land flooding in the history of the earth took place; as a result, most of it was covered with huge swamps; arthropods and cephalopods were common in the seas. The first jawless vertebrates appear (for example, the current cyclostomes - lampreys). These were benthic forms feeding on organic remains. Their body was covered with shields that protected them from crustaceans, but they did not yet have an internal skeleton.
Approximately 440 million years ago, two significant events occurred at once: the emergence of plants and invertebrates on land. In the Silurian, there was a significant uplift of land and a retreat of ocean waters. At this time, along the marshy shores of reservoirs, in the tidal zones, lichens and the first terrestrial plants appeared, resembling algae - psilophytes. As an adaptation to life on land, the epidermis with stomata, the central conducting system, and mechanical tissue appear. Spores are formed with a thick shell, protecting from drying out. Subsequently, the evolution of plants went in two directions: bryophytes and higher spores, as well as seed ones.
The emergence of invertebrates on land was due to the search for new habitats, the absence of competitors and predators. The first terrestrial invertebrates were tardigrades (which tolerate desiccation well), annelids, and then centipedes, scorpions and arachnids. These groups originated from trilobites often stranded on the shallows at low tide. On fig. 3 shows the main representatives of the early Paleozoic animals.
Rice. 3. Early Paleozoic: 1-archaeocyates, 2,3-intestinal (2-four-beam corals, 3-jellyfish), 4-trilobites, 5,6-molluscs (5-cephalopod, 6-gastropod), 7-brachiopods, 8, 9-echinoderms (9-sea lilies), 10-graptolites (semi-chordates), 11-jawless fish-like.
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