The Paleozoic era spans a huge time span of about 542 to 250 million years ago. Its first period was the "Cambrian", which lasted about 50 -70 (according to various estimates) million years, the second - "Ordovician", the third - "Silurian", 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, whose climate at the beginning was temperate, with a predominance of seas and low-lying land, contributed to the prosperity of algae.

They are believed to have created the atmosphere

They came from worms

The Paleozoic era was the time of the birth and ancestors of modern cephalopods - squids, octopuses, cuttlefish. Then they were small creatures with horny shells, through which a siphon passed, allowing the animal to fill parts of the shells with water or gases, changing its buoyancy. Scientists believe that ancient cephalopods and molluscs evolved from ancient worms, the remains of which have survived a little, since they consisted mainly of soft tissues.

The Paleozoic era, whose plants and animals either replaced each other, or coexisted side by side for millions of years, gave life to cystoids as well. These creatures, attached to the bottom with a limestone cup, already had tentacle arms, which pressed the particles of food passing by to the cystoid feeding organs. That is, the animal has moved from passive waiting, as in archaeocyates, to the production of food. Scientists also attributed the discovered fish-like creature, which had a spine (chord), to the early Paleozoic.

Three-meter shellfish ... with a poisonous sting

But the development of primitive fish got in the Silurian and Ordovician, where they were jawless, shell-covered creatures, with organs that emit electrical discharges for protection. In the same period, you can find giant nautiloids with three-meter shells and no less large crustaceans, up to three meters long.

The Paleozoic era was rich in climate change. So, in the Late Ordovician it got significantly colder, then it got warmer again, in the Early Devonian the sea receded significantly, there was an active volcanic mountain building. But it is the Devonian that is called the era of fish, since cartilaginous fish were very common in the water - sharks, rays, cross-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, the table of the development of life forms during which is presented above, has left many mysteries that have yet to be solved by scientists.

Eon - Phanerozoic The beginning of the era 541 million years ago The end of the era 298, 9 million years ago Duration 242, 1 million years ago

Periods Paleozoic Cambrian Ordovician Silurian Devonian Carboniferous Permian (D) (C) (P) (S) (O) (€) 541 485, 4 443, 4 419, 2 358, 9 298, 9 Duration (Ma) 55, 6 42 42 24, 2 60, 3 60

TECTONICS Cambrian Began about 542 million years ago, ended 488 million years ago, the Cambrian lasted for about 54 million years. By the beginning of the era and throughout the Cambrian, ancient platforms (South American, African, Arabian, Australian, Antarctic, Hindustan), 180 °, were combined into a single supercontinent called Gondwana.

Ordovician Ordovician, the second from the bottom system of the Paleozoic group, corresponding to the second period of the Paleozoic era of the geological history of the Earth. It is underlain by the Cambrian and overlapped by the Silurian systems. It began 485.4 ± 1.9 million years ago, ended 443.4 ± 1.5 million years ago. Thus, it lasted for about 42 million years. In the Ordovician, Gondwana, moving south, reached the region of the South Geographic Pole (now it is the northwestern part of Africa). The oceanic lithospheric plate Proto-Farallon (and probably the Proto. Pacific plate) under the northern margin of the Gondwana plate was underway. A contraction of the Proto-Atlantic Basin, located between the Baltic Shield, on the one hand, and the united Canada-Greenland Shield, on the other hand, began, as well as a shrinkage of oceanic space. Throughout 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 Chinese.

Silurian 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, ended 419, 2 ± 3, 2 million years ago. Thus, it lasted for about 24 million years. As a result, the relief of the earth's surface at the end of the Silurian period became elevated and contrasting, especially on the continents located in the northern hemisphere. the Caledonian folding continued.

Devonian Devonian (Devonian period, Devonian system) - the fourth geological period of the Paleozoic era. It began 419.2 ± 3.2 million years ago, ended 358.9 ± 0.4 million years ago. Thus, it lasted for about 60 million years. In the Early Devonian, the Proto-Atlantic Basin closes and the Euro is formed. American mainland as a result of the Pro collision. European mainland with Pro. North American in the area of ​​what is now Scandinavia and West Greenland. In the Devonian, the displacement of Gondwana continues, as a result of which the South Pole is in the southern region of modern Africa, and possibly present-day South America.

Carboniferous Kamennougol period, abbreviated as carbon (C), is the penultimate (fifth) geological period of the Paleozoic era. It began 358.9 ± 0.4 million years ago, ended 298.9 ± 0.15 million years ago. Thus, it lasted for about 60 million years. In the Middle Carboniferous, there was a collision between Gondwana and Euro-America. As a result, a new supercontinent Pangea was formed. In the Late Carboniferous - Early Permian, the Euro collided. The American continent with the Siberian, and the Siberian continent with the Kazakhstan continent.

Perm The Permian period (Perm) is the last geological period of the Paleozoic era. It began 298, 9 ± 0, 15 million years ago, ended 252, 17 ± 0, 06 million years ago. Thus, it lasted for about 47 million years. The deposits of this period are underlain by Carboniferous and overlapped by Triassic ones. By the end of the Paleozoic, in the Permian period, Pangea stretched from the South Pole to the North.

Cambrian Onshore, intense prospecting took place, a large amount of precipitation was washed away into the seas. The oxygen content in the atmosphere gradually increased. Towards the end of the period, glaciation began, leading to a decrease in sea level.

Ordovician Large land masses are concentrated closer to the equator. Throughout the period, land masses shifted farther and farther south. The old Cambrian ice sheets have melted and sea levels have risen. 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. Began with the era of glaciation. As the ice melted, the sea level rose and the climate became milder.

Devonian Rivers carried mountains of precipitation into the seas. Vast swampy deltas were formed. By the end of the period, the sea level had dropped. The climate has warmed over time and became harsher with alternating periods of heavy rains and severe droughts. Large areas of the continents have become waterless.

Carboniferous In the early Carboniferous, shallow coastal seas and marshes were spread over vast areas, and an almost tropical climate was established. Enormous forests with lush vegetation have significantly increased the oxygen content of the atmosphere. Later it got colder, and at least two large glaciations occurred on Earth.

The Permian Period began with glaciation, which caused a drop in sea levels. As Gondswana moved northward, the land warmed up and the ice gradually melted. It became very hot and dry in Laurasia, and vast deserts spread across it.

Cambrian Fauna In the course of a grandiose evolutionary explosion, most modern animal types arose, including microscopic foraminifera, sponges, sea stars, sea urchins, sea lilies and various worms. In the tropics, archaeocyates. erected huge reef structures. The first hard-skinned animals appeared; the seas were dominated by trilobites and brachiopods. The first chordates arose. Later, cephalopods and primitive fish appeared.

Ordovician Fauna: A sharp increase in the number of animal filters, including bryozoans (sea mats), sea lilies, brachiopods, bivalve molluscs and graptolites, which flourished in the Ordovician. Archaeocyates have already become extinct, but stromatoporoids and the first corals picked up the reef-building baton from them. The number of nautiloids and jawless armored fish increased.

Plant kingdom: There were various types of algae. In the late Ordovician, the first true terrestrial plants appeared.

Silurian Fauna: Nautiloids, brachiopods, trilobites and echinoderms thrive in the seas. The first jawed acanthodes appeared. Scorpions, centipedes, and possibly eurypterids have begun to make their way onto land. Formation of the main classes of invertebrates, the first primitive vertebrates (jawless and fish) appeared.

Devonian Fauna: Rapid evolution of fish, including sharks and rays, cross-finned and ray-finned fish. The land has been invaded by many arthropods, including ticks, spiders and primitive wingless insects. The first amphibians also appeared in the Late Devonian.

Plant life: 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 various vascular plants has increased. Spore lycophytes (lycophytes) and horsetails appeared, some of them developed into true trees 38 m high.

Carboniferous Fauna: Ammonites appeared in the seas, the number of brachiopods increased. Rugos, graptolites, trilobites, as well as some bryozoans, sea lilies and molluscs became 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 the shores of vast swamps are overgrown with dense forests of giant ploons, horsetails, tree ferns and seed plants up to 45 m high. The undecomposed remains of this vegetation have over time turned into coal.

Permian Fauna: Bivalve molluscs evolved rapidly. Ammonites were abundant in the seas. Amphibians prevailed in fresh water bodies. Aquatic reptiles also appeared, including mesosaurs. During the great extinction, over 50% of animal families disappeared. On land, reptiles took over the amphibians.

Flora: Forests of large seed ferns-lossopteris have spread over the southern land masses. The first conifers appeared, quickly settling inland areas and high mountains. Among terrestrial plants, arthropod ferns and gymnosperms predominated.

Conclusion: The Paleozoic era (Greek "palayos" - ancient, "zoe" - life) - the era of ancient life. Its age is 570 million years. It is subdivided into 6 periods (Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian). The plant world developed from algae to the first seed plants (seed parorotniks). The animal world developed from primitive sea cranial chordates to terrestrial reptiles. In the Silurian period, the first inhabitants of the land appeared - psilophyte plants and arachnid invertebrates. These were the first animals to breathe atmospheric oxygen.

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Palaeozoic occupies a time interval of 289 million years. The third era of the development of the Earth lasted from 540-252 million years ago and followed the Proterozoic (Proterozoic era). The Paleozoic era is divided into 6 geological periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous (Carboniferous) and Permian (Permian).

Let's take a closer look at periods of the Paleozoic era.

Cambrian... The first period of the Paleozoic era lasts 56 million years. At this time, there is an active formation of mountain ranges. Only bacteria and algae can still live on earth. But in the depths of the sea, a variety of living organisms reign. Trilobites appear - invertebrate arthropods, similar to modern representatives of the crayfish family. In reservoirs, the amount of magnesium and calcium increases. Mineral salts contained in the earth begin to flow into the seas in large quantities. This makes it possible for animals living in water to evolve - to create a solid skeleton.

Ordovician... The second eratema of the Paleozoic era covers a time interval of 42 million years. This period is characterized by the flourishing of life on the planet. The main types of marine inhabitants are formed. The first armored jawless fish, starfish and lilies, huge scorpions appear. At the end of the Ordovician period, the first representatives of vertebrates appear.

Silurian... The Silurian, following the Ordovician, lasts 24 million years. This is the era of the conquest of land by the ancient ancestors of spiders, centipedes and scorpions. Armored jaw fishes appear. At the beginning of the Silurian, more than half of the existing living organisms die out. In the northern part of the Earth, the continent of Lawrence is being formed. Gondwana is divided into 2 parts by the newly formed sea bay. The land gradually goes under water - this leads to the formation of sedimentary rocks. At the end of the Silurian period, the stage of the Caledonian development ends. The mountain ranges of Scotland and Greenland are beginning to form, a small part of the Cordillera is formed. In the place of modern Siberia, the Angarida continent is formed.

Devonian... The Devonian period lasts 61 million years. The first sharks, insects and amphibians appear. The land is becoming more and more green. Now ferns and psilophytes live on it. The remains of dying plants form coal seams. The first rocks are formed on the territory of modern England. The continents of Lawrence, Baltic and Avalonia collide and form a single continent. Gondwana is shifting from south to north. Huge deserts are forming within the continents. In the mid-Devonian, the polar glaciers begin to melt. As a result, the ocean level rises - this contributes to the formation of coral reefs off the coast of Laurentia.

Carboniferous period (Carboniferous)... The fifth period of the Paleozoic era bears another name - Carboniferous. Its duration is 60 million years. This is the time of the formation of the main deposits of coal. At the beginning of the Carboniferous, the Earth is covered with ferns, lepidodendrons, moons, cordaites. By the end of the erathema, coniferous forests appear. Higher insects are born - cockroaches and dragonflies. The first reptiles and the ancestors of squid, the belemnites, appear. The main continents of that time are Laurasia and Gondwana. Insects begin to master the air. The dragonflies are the first to take off. Then butterflies, beetles and grasshoppers rise into the air. The first mushrooms, moss and lichens appear in the forests. Studying the carbonic flora, one can observe the evolutionary process of plants.

Permian period (Perm)... The final period of the Paleozoic era lasts about 46 million years. It begins with another glaciation in the south of the planet. As the mainland of Gondwana moves from south to north, the ice caps begin to melt. A very hot climate is established in Laurasia, which leads to the formation of giant desert zones. At the border of the Carboniferous and the Permian period, bacteria begin to process wood. Thanks to this significant event, the next oxygen catastrophe threatening all living things never happened. The dominance of vertebrates arises on earth. The ancestors of mammals appear - the animal-like lizards therapsids. Bony fish predominate in the seas. By the end of the era, the extinction of trilobites, crustaceans and some coral species occurs. There are fewer lepidodendrons and sigillaria. Lingual ferns, conifers and gingko trees, cycads (ancestors of palms), and kordaites (ancestors of pines) develop. Living organisms begin to colonize in arid regions. The best acclimatization occurs in reptiles.

Paleozoic climate

Paleozoic climate most of all similar to the climate of the modern world. At the beginning of the era, a warm climate with low climatic zoning prevails. At the end of the Paleozoic, aridity develops and a sharp zoning is formed.

In the first half of the Cambrian period, nitrogen content predominated in the atmosphere, the level of carbon dioxide was no higher than 0.3%, and the amount of oxygen gradually increased. The weather was humid and hot on the continents.

In the second half of the Ordovician, the planet became sharply colder. During the same period, zones with tropical, subtropical, temperate and equatorial climates were formed. In the subtropics, the average air temperature dropped by 15 degrees, in the tropics - by 5 degrees. The mountain ranges of Gondwana, located at the South Pole, are covered with glaciers.

By the beginning of the Carboniferous period, tropical and equatorial types of climate reigned on Earth.

The development of plant life on land contributed to the active process of photosynthesis with an increased decrease in the level of carbon dioxide in the atmosphere and an increase in the oxygen content. The formation of the Pangea continent led to the cessation of the formation of precipitation and the limitation of the connection of the equatorial seas with the polar ones. As a result of these events, there was a strong cooling with a pronounced temperature difference at the equator and poles.

During the Paleozoic era 2 tropical, 2 subtropical, 2 temperate and 1 equatorial climatic zones have formed on the planet. By the end of the Paleozoic era, the cool climate again changed to a warm one.

Paleozoic animals

In the Cambrian era of the Paleozoic era, trilobites - invertebrate arthropod cancer-like creatures - dominate in the oceans and seas. Their bodies were protected by strong chitinous shells, divided into about 40 parts. Some individuals reached a length of more than 50 cm. Trilobites ate marine plants and the remains of other animals. Another species of multicellular Cambrian animals that became extinct by the beginning of the Ordovician is archaeocyates. These creatures are similar to the coral reefs of our time.

The Silurian period was dominated by trilobites, molluscs, brachiopods, sea lilies, starfish and sea urchins. A distinctive feature of the Silurian bivalve molluscs was the bending of their valves in different directions. In most of the gastropods, the shells turned to the right side. Their cephalopods had smooth, horny shells. At the same time, the first vertebrates - fish - appear.

In the Carboniferous period, representatives of marine inhabitants - foraminifers and schwagerins - became widespread. Many limestone deposits are formed from their shells. Sea lilies and hedgehogs develop, and products are representatives of brachiopods. Their sizes reached 30 cm. Long branches ran along the edge, with the help of which the products were attached to underwater plants.

During the Devonian, the seas were dominated by placoderms - fish with strong jaws and a hard shell that protected the head and front of the body. These are the largest predatory fish of that time. Dunkleosteus, a type of placoderm, was up to 4 meters long and resembled the cladoselachia, the first sharks, in structure. In the reservoirs of this time period, shellless fish, similar to modern ones, were found. They are divided into 2 groups: cartilaginous and bone. Cartilaginous fish are the forerunners of the sharks and rays of our time. Their mouths were full of sharp teeth, and their bodies were covered with hard scales. Bony fish were small in size, with thin scales and mobile fins. According to scientists, four-legged vertebrates originated from lobe-finned bony fish. In the Devonian period, the first ammonites appear - predatory mollusks with a spiral shell. They had an upper shell with partitions. The ammonites filled the empty space between these partitions with water and gas. Due to this, their buoyancy properties changed for the better.

By the end of the Paleozoic era, reptiles begin to flourish. Reptiles have adapted to a changeable climate faster than all other living things. Found fossilized skeletons allow you to recreate the appearance of animals in full. One of the largest herbivores of that time was the Moschops. The reptile had a long tail, a large skull, and a barrel-like body. Its dimensions reach 4 meters in length. A predator similar in size to the Moschops is the Anthosaurus.

Plants of the Paleozoic era

The first plants to fill the land were psilophytes. Later, other types of vascular originated from them - lyes, horsetails, ferns. The humid climate of the Carboniferous gave the development of the prototypes of tropical forests. Lepidodendrons and sigillaria, calamites and cordaites, ferns grew in them.

By the middle of the Permian period, the climate becomes dry. In this regard, moisture-loving ferns, calamites and tree-like lymphoids disappear.

In the Ordovician, sea lilies develop. They were attached to the bottom with a stem consisting of ring-shaped parts. They had moving rays around their mouths, with which the lilies caught food in the water. Often, sea lilies formed dense thickets.

In the middle of the Paleozoic era, arthropod plants arose, which are divided into 2 groups - cuneiform and calamite. The first group consists of plants living in water. They had a long, uneven stem with leaves. Spores formed in the kidneys. On the surface of the water, wedge-leaved ones kept with the help of branched stems. Calamites are tree-like plants that form swamp forests. They reach a height of 30 meters.

Minerals of the Paleozoic era

The Paleozoic era is rich in minerals. During the Carboniferous, the remains of animals and dying plants formed huge deposits of coal. In the Paleozoic era, deposits of oil and gas, rock and mineral salt, copper, manganese and iron ores, limestone, phosphorite and gypsum were formed.

Paleozoic era and its periods will be discussed in more detail in the following lectures.

Paleozoic era: Cambrian period (from 540 to 488 million years ago)

The beginning of this period was laid by an amazingly powerful evolutionary explosion, during which representatives of most of the main groups of animals known to modern science first appeared on Earth. The boundary between the Precambrian and the Cambrian passes through rocks, which suddenly reveal an amazing 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 split into two continents - northern (Laurasia) and southern (Gondwana). There was a significant erosion of the land, volcanic activity was very intense, the continents either subsided or rose, resulting in the formation of shoals and shallow seas, which sometimes dried up for several million years, and then re-filled with water. At this time, the oldest mountains appeared in Western Europe (Scandinavian) and in Central Asia (Sayan).

All animals and plants lived in the sea, however, the tidal 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 Charles Walcott, was represented mainly by benthic organisms such as archaeocyates (coral analogs), 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 became extinct by the end of the Permian period; from horseshoe crabs, only representatives of one family have survived to this day. Approximately 30% of Cambrian species were brachiopods - marine animals with a bivalve shell, similar to molluscs. From trilobites that have gone over to predation, crustaceans up to 2 m long appear.At the end of the Cambrian period, cephalopods appear, including the genus Nautilius, which has survived to this day, and from echinoderms, primitive chordates (tunicates and cranials). The appearance of the chord, which gave the body rigidity, was an 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 mainland 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. At first, this ocean reached a width of about 2,000 km, then began to narrow again as the land masses that form Europe, North America and Greenland gradually began to converge, until finally they merged into a single whole. During the Silurian period, Siberia "swam" to Europe (the Kazakh Upland was formed), Africa collided with the southern part of 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 powerful land flooding in the history of the earth occurred, as a result, most of it was covered with huge swamps ‚arthropods and cephalopods were widespread in the seas. The first jawless vertebrates appear (for example, the present-day cyclostomes — lampreys). These were bottom forms feeding on organic debris. Their body was covered with shields that protected them from crustaceans, but there was not yet an internal skeleton.

Approximately 440 million years ago, two significant events took place at once: the emergence of plants and invertebrates on land. In the Silurian, a significant uplift of the land and the retreat of ocean waters were observed. At this time, lichens and the first terrestrial plants resembling algae - psilophytes - appear along the swampy shores of reservoirs, in tidal zones. 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, which prevents drying out. In the future, the evolution of plants went in two directions: bryophyte and higher spore, as well as seed.

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 drying well), annelids, and then millipedes, scorpions and arachnids. These groups originated from trilobites often found in the shallows at low tide. In fig. 3 shows the main representatives of animals of the early Paleozoic.

Rice. 3. Early Paleozoic: 1-archaeocyates, 2,3- intestinal stripes (2-four-beam corals, 3-jellyfish), 4-trilobite, 5,6-molluscs (5-cephalopods, 6-gastropods), 7-brachiopods, 8, 9-echinoderms (9-sea lilies), 10-graptolite (semi-chordate), 11-jawless fish-like.