The history of the Earth before the appearance of hominids

Main article: Earth (planet)

Aeons and eras

Precambrian: Catharchean, Archaean, Proterozoic

Eon (eonotema)		Era (eratema)	Period (system)	Epoch (department)	Beginning, years ago (September 2010, dates rounded)	Main events
Precambrian	Proterozoic	Neoproterozoic	Ediacaran Period		~ 635 million	First multicellular animals.
			Cryogenian Period		720 million	Vendian glaciation is one of the largest glaciation of the Earth
			Tonian Period		1.0 billion	The beginning of the collapse of the supercontinent Rodinia
		Mesoproterozoic	Steniy		1.2 billion	Supercontinent Rodinia, Superocean Mirovia
			Ectasius		1.4bn	First multicellular plants (red algae)
			Kalimius		1.6 billion
		Paleoproterozoic	Staterius		1.8 billion
			Orosirius		2.05 billion
			Rhyacian		2.3 billion
			Siderian		2.4 billion	Earth became aerobic about 2.4 billion years ago, when photosynthetic microbes and then plants began producing oxygen in large quantities.
	Archean	Neoarchean			2.8 billion
		Mesoarchean			3.2 billion
		Paleoarchean			3.6 billion
		Eoarchean			4 billion	The emergence of primitive unicellular organisms
	Hadean				~ 4.6 billion	~ 4.6 billion years ago - the formation of the Earth.

4.6 billion hp: Catharcheus: Earth formation and asteroid bombing

Main article: Catharcheus (Gadey, Prearchean)

3.5 billion hp: Minerals became part of a living cell

Main article: The body's need for minerals

Minerals became part of a living cell at the very beginning of biological evolution - about 3.5 billion years ago, and the lack of any of them causes disorders in the work of the entire human body until now.

2.4 billion hp: Oxygen disaster due to cyanobacteria emissions and Huron glaciation

The oldest glacial era falls on the early proterosis and is associated with an oxygen catastrophe. Photosynthetic organisms, the lion's share of which were cyanobacteria, were the first to learn to pollute the atmosphere, throwing toxic waste products into it. Such a product was oxygen. The main greenhouse gas of the primary atmosphere, methane, turned out to be oxidized a little less than completely, and about 2.4 billion years ago the temperature on Earth fell from + 54 ° C to -40 ° C. The advancing Huron glaciation is considered the largest in history: the whole Earth was covered with an ice shell, and even in the tropics the thickness of the glaciers was several hundred meters.

Anaerobic organisms that fed on methane almost died out, and photosynthetics did not have to sweetly.

2.1 billion hp: The greenhouse effect of carbon dioxide from volcanoes completed the Huron glaciation

Carbon dioxide entering the atmosphere through volcanoes gradually accumulated until the greenhouse effect worked, ending the Huron glaciation 2.1 billion years ago.

1.9 billion hp: Proterozoic - the era of the emergence of multicellular organisms - sponges, jellyfish, mollusks, sea urchins and stars

Proterozoic (1.9 billion - 570 million years ago) is the era of the emergence of multicellular organisms. The cells combined, grew in size, and membranes and nuclei formed. In her marine laboratory, life created various variants of the structure of living organisms. Some resembled living filters that passed through their bodies huge volumes of water - sponges.

The body of others resembled a translucent bag in which food caught by poisonous tentacles, jellyfish polyps, hydras were digested. Their scientific name is intestinal.

The soft tissues of the third were covered with strong shell armor - mollusks.

Worms, divided into segments, crawled along the bottom. And spikes grew on others, echinoderms appeared - sea urchins, stars.

The world of the great ocean of the Proterozoic era was bizarre and diverse. But life was constantly changing, and soon more developed organisms entered the arena of life.

1.27 billion hp: Formation of the supercontinent Rodinia

It is believed that the supercontinent Rodinia (from the Russian word "Homeland") was formed between 1.3 and 1.23 billion years ago.

Unlike later supercontinents, Rodinia was completely lifeless. It existed before the difficult life appeared on land. Based on sedimentary rock analysis, Rodinia's formation occurred when the ozone layer was not as extensive as it is now. Ultraviolet light prevented organisms from inhabiting the continent. Nevertheless, its existence significantly affected the marine flora and fauna of that time.

717 million hp: Stertskoe and Marinoan glaciation - Snowball Earth

As of January 2023, it is believed that the Sturt glaciation lasted from about 717 million years ago to 660 million years ago, that is, approximately 57 million years.

The Marinoan glaciation occurred no earlier than 654.5 million years ago and ended approximately 632.3 ± 5.9 million years ago during the Cryogenian period.

The beginning of "Snowball Earth" could be caused by many possible reasons, such as

• reducing the concentration of greenhouse gases in the atmosphere, including methane and/or carbon dioxide,
• the eruption of the supervolcano,
• changes in solar power generation or
• disturbances of Earth's orbit.

Tropical locations of continents reflected more sunlight, led to increased precipitation and reduced greenhouse gases

The tropical location of the continents, perhaps contrary to common sense, is necessary for the Earth to become a "snow ball." Tropical continents reflect more solar heat than the open ocean, and therefore absorb less solar energy: most of the solar energy absorbed by the Earth today falls on tropical oceans.

In addition, tropical continents receive more rainfall, resulting in increased river flow and erosion. Upon contact with air, silicate rocks enter weathering reactions, as a result of which carbon dioxide, which is a gas greenhouse gas, is removed from the atmosphere. Geologically, this compensates for carbon dioxide emissions from volcanoes into the atmosphere.

Typically, when the Earth cools due to natural climatic fluctuations and changes in incoming solar radiation, cooling slows down these weathering reactions. As a result, less carbon dioxide is removed from the atmosphere and the Earth heats up as this greenhouse gas accumulates - this negative feedback process limits the degree of cooling. However, during cryogeny, all Earth's continents were likely in tropical latitudes, making the process less efficient as high weathering rates continued on land even as the Earth cooled. This led to the fact that the ice spread beyond the polar regions.

The collapse of Rodinia led to a rise in world ocean levels, an increase in precipitation and a decrease in greenhouse gases

The Rodinia supercontinent fault produced new oceans and seafloor expansions, resulting in warmer and less dense oceanic crust. The lower density hot oceanic crust is not as deep as the older, cooler oceanic lithosphere. During periods with relatively large areas of the new lithosphere, the oceanic floor rises, causing sea level rise. The result was a larger number of shallower seas.

An increase in the surface area of ​ ​ the oceans from which water evaporates could lead to an increase in precipitation, which, in turn, increased the weathering of exposed rocks and, again, a decrease in greenhouse gas levels.

Additional factors that may have contributed to the onset of the Neoproterozoic "snowball" include the appearance of free oxygen in the atmosphere, which could reach enough to react with methane in the atmosphere, oxidizing it to carbon dioxide, a much less potent greenhouse gas.

Regardless of the cause, initial cooling leads to an increase in the surface area of ​ ​ the Earth covered with ice and snow, and additional ice and snow reflect more solar energy back into space, which leads to further cooling of the Earth and an even greater increase in the surface area of ​ ​ the Earth covered with ice and snow. This positive feedback cycle can eventually cause the equator to freeze and become as cold as modern Antarctica.

It is assumed that during the cryogenic period, the release of carbon dioxide was unusually low, which contributed to the preservation of global glaciation.

While the presence of glaciers is not disputed, the idea that the entire planet was covered in ice is more controversial. Some scientists suggest that a strip of non-freezing water or water with moving ice remained around the equator, which allowed the hydrological cycle to continue. This hypothesis attracts scientists who observe certain features of sedimentary rocks that could only form under open water or fast-moving ice (for which it was necessary to move somewhere where there was no ice). Studies have revealed geochemical cyclicity in clastic rocks, showing that periods of "snowball" alternated with warming periods similar to ice age cycles in recent Earth history.

The Snowball Earth hypothesis does not explain the alternation of ice and interglacial periods, as well as fluctuations in the boundaries of ice sheets.

Attempts to create computer models of the Earth in the form of a "snowball" hardly explain the global ice sheet without fundamental changes in the laws and constants governing the planet.

The less extreme Earth-Snowball hypothesis suggests a constant change in the configuration of continents and ocean circulation. Based on the generalized data, the Earth-Snowman models were created, in which the stratigraphic record does not suggest complete global glaciation. Kirschwink's original hypothesis assumed that warm tropical puddles should have existed on Snowball Earth.

A more radical hypothesis of the Earth-Water Belt suggests that ice-free sections of the ocean continued to exist even during glaciation of tropical continents.

632 million hp: Methane from volcanoes, permafrost and microbes leads to the end of glaciation and the flow of valuable elements into the ocean, which supports the complication of life forms

The level of carbon dioxide required to thaw the Earth was 350 times higher than the modern one and amounted to about 13% of the atmosphere. Since the Earth was almost completely covered with ice, carbon dioxide could not be removed from the atmosphere due to the release of alkali metal ions as a result of weathering of siliceous rocks. Within 4 to 30 million years, sufficient CO2 and methane, mainly released by volcanoes, but also produced by microbes that convert organic carbon, located under the ice, into gas, would accumulate in sufficient quantity, to eventually produce a greenhouse effect sufficient to, so that surface ice in the tropics melts, and a strip of land and water constantly free from ice is formed; it would be darker than ice and therefore absorb more solar energy, triggering "positive feedback."

Strontium isotope data were found to contradict proposed "Snowball Earth" models, in which silicate weathering ceased during glaciation and accelerated immediately thereafter. It has therefore been suggested that the source of the large amount of carbon recorded immediately after glaciation was methane released from permafrost during marine transgression.

On continents, melting glaciers have resulted in the release of vast amounts of glacial deposits, including volcanism products, which have been eroded and weathered. The resulting sediments that entered the ocean contained many nutrients, such as phosphorus, which, combined with excess CO2, led to an explosive increase in the cyanobacteria population, which caused a relatively rapid saturation of the atmosphere with oxygen and possibly contributed to the heyday of the Ediacaran biota and the subsequent Cambrian explosion - a higher concentration of oxygen allowed large multicellular life forms to develop.

Although positive feedback led to melting of ice in a geologically short time, possibly in less than 1000 years, replenishing oxygen reserves in the atmosphere and reducing CO2 levels took several more millennia.

Perhaps the level of carbon dioxide has decreased so much that the Earth froze again. This cycle could be repeated until the continents moved to more polar latitudes.

Phanerozoic: Paleozoic, Mesozoic and Cenozoic

Phanerozoic Aeon, Phanerozoic (ancient Greek phaneros "explicit, open, visible" and the "life" call) - the fourth and current geological eon in the history of the Earth, which began 538.8 ±0,6 million years ago, the time of the ubiquitous and pronounced presence on the planet of developed plant and animal life.

Eon (eonotema)		Era (eratema)	Period (system)	Epoch (department)	Beginning, years ago (September 2010, dates rounded)	Main events
Phanerozoic		Cenozoic	Quaternary (Anthropogenic)	Holocene	11.7 thousand	End of the Ice Age. The Emergence of Civilizations
				Pleistocene	2.588 million	The extinction of many large mammals. The emergence of modern man
			Neogene	Pliocene	5.33 million
				Miocene	23.0 million
			Paleogene	Oligocene	33.9 ± 0.1 mln	The emergence of the first great apes.
				Eocene	55.8 ± 0.2 million	The emergence of the first "modern" mammals.
				Paleocene	65.5 ± 0.3 million
		Mesozoic	Cretaceous		145.5 ± 0.4 mln	First placental mammals. Extinction. dinosaurs
			Jurassic		199.6 ± 0.6 million	The emergence of marsupial mammals and first birds. The heyday of dinosaurs.
			Triassic		251.0 ± 0.4 mln	First dinosaurs and oviparous mammals.
		Paleozoic	Perm		299.0 ± 0.8 mln	About 95% of all existing species died out (Mass Permian extinction).
			Coal		359.2 ± 2.8 million	Appearance of trees and reptiles.
			Devonian		416.0 ± 2.5 mln	The emergence of amphibians and spore plants.
			Silurian		443.7 ± 1.5 million	Landfall: scorpions; the appearance of maxillary
			Ordovician		488.3 ± 1.7 million	Racoscorpions, the first vascular plants.
			Cambrian		542.0 ± 1.0 mln	The emergence of a large number of new groups of organisms ("Cambrian explosion").

560 million years of evolution in a few seconds in the video below.

541 million hp: The beginning of the Paleozoic era and its first period - Cambrian - skeletal revolution

Paleozoic (541-251 million years ago) is a geological era in the history of planet Earth, known as the era of ancient life. First era of the Phanerozoic eon. Divided into 6 periods:

• Cambrian,
• Ordovik,
• Silurus,
• Devonian,
• carbon and
• Perm.

It was in this era that land development began. At the beginning of the era, the southern continents were united into a single supercontinent Gondwana, and by its end other continents joined it and the supercontinent Pangea was formed.

Cambrian (540-485 Ma). One of the most important events of the "skeletal revolution."

Organisms dressed in hard skeletons: outer and inner shells, houses, rigid spikes. This meant that there was about as much oxygen as there is now. The first soil invertebrates and millipedes appeared in the Cambrian. All living organisms formed a single complex - the biosphere.

Thousands of trilobite species in seas up to a meter long

Trilobites are the most interesting "three-bladed" creatures that appeared in the Cambrian. Thousands of their species lived in the seas. Some were giants up to a meter in length, others about a centimeter.

Trilobites have become distant relatives of all arthropods that now inhabit our planet - crustaceans, spiders, insects. All trilobites are extinct, none have survived to our time.

"Trilobite" means "tridole." You might think that such a name reflects the plan of the structure of the head, body, tail. In fact, the name is associated with those parts of the body that stretch along its axis, separated by longitudinal furrows, and not the transverse boundaries of the segments. These furrows divide each trilobite into an axial part running in the middle and two lateral on each side of it.

Throughout its history, trilobites have created an amazing variety of shapes, preserving the overall plan of the structure.

One of the neighbors of trilobites was a variety of molluscs, echinoderms (sea stars, hedgehogs, etc.), brachiopods. In general, in the Cambrian period, the main types of animal kingdoms appear.

Pikaya with chord - ancestor of fish

The earliest ancestors of fish were probably animals similar in structure to lancets - such as picaia, Haіkouіchthys and Myllokunmіngіa. These three genera appeared about 530 million years ago during the Cambrian explosion, when the number of taxa of the animal kingdom increased sharply. The pikaya had a primitive chord, which later modified into the spine. Unlike other representatives of the fauna that dominated Cambrian waters, the pikaya body consisted of a chord, embryonic vertebrae and a clearly defined head and tail.

485 million hp: Ordovik

Ordovik (485-443 million years ago). The Ordovician period is one of the least studied and investigated geological periods in the history of the Earth. He did not witness the same surge in evolutionary activity that characterized the preceding Cambrian period: rather, it was a time when the earliest arthropods and vertebrates expanded their presence in the oceans.

Racoscorpions

Racoscorpions became dangerous enemies of the oldest vertebrates, huge arthropods reached up to three meters in length. Some were armed not only with claws, but also with a poisonous spike on the tip of the tail. They were distant ancestors of modern poisonous spiders and scorpions, as well as harmless hayfields and phalanxes.

The only closest relatives of racoscorpions who have survived to our time are sword-tails. Like trilobites, they dig in the ground, catching edible fines with small claw legs.

Molluscs appeared that had "upright" rakavins, they got the name - orthoceratids are so translated from the Greek appearance of their shells, but crawling with such shells was inconvenient.

In their descendants, the shells began to twist. Such molluscs were called ammonites, after the Egyptian god Ammon, who was depicted with the head and horns of a ram. Their dimensions sometimes reached up to 5 meters.

Sea lilies or crinoids

Sea lilies, or crinoids, are the most developed group of fine stalked echinoderms. During the Paleozoic era, they were the most numerous, most widespread, and most successful. Crinoids appeared in the Early Ordovician. Although many crinoids became extinct by the end of the Paleozoic, some continue to exist today. The area of ​ ​ their distribution of the sea and the ocean, it extends from sunlit shallow waters and reefs to dark, cold waters about 4,000 meters or more deep.

Some crinoids reach 15-18 m in length, and the arms of the Cretaceous genus are 1.2 m in length. Numerous communities lived in the shallow seas of the Devonian and Carboniferous, where their remains were part of carbonate sediments.

More than 6,000 species of fossil crinoids are known. In modern seas, there are 25 genera of stalked and 19 genera of stemless sea lilies. Most often there are segments of various shapes and pieces of stems, many less often - calyx.

443 million hp: Silur. The first lamellar fish are placoderms. Algae made landfall

Silurus (443-419 million years ago) was marked by the appearance of the first fish. They had no swimming bubbles. Their gills gradually transformed and created a jaw.

Fossil remains of vertebrates - well-protected lamellar fish - were found in Silurian rocks about 500-430 million years.

Placoderms, or lamellar fish (outdated. shell fish) - a class of maxillary (Gnathostomata) living in the Paleozoic. The heyday of lamellar fish fell on the Devonian.

The term "placoderms" suggests that the shell that protected their body was rigid plates covered on top with skin rather than a stratum corneum.

Early placoderms lived exclusively in seawater, but later moved to brackish water bodies. During the Devonian, placoderms continued to inhabit and dominate almost all known aquatic ecosystems, both freshwater and saline.

During this period, algae made landfall. A completely new stage in the development of life has begun. Lifeless rocks began to be covered with the first vegetation.

419 million hp: Devon - the kingdom of fish

Devon (419-359 million years ago) - this period became a real kingdom of fish. By level of development, taxonomic groups - this was the most advanced class of living organisms in the Devonian.

The first jaw fish appeared at the end of the Ordovician and became widespread in the Devonian, which is why the period is called the "era of fish."

Bony fish - ancestors of all land animals - make attempts to make landfall

In the Devonian, fish have a real bone skeleton. A lung formed from the outgrowth of the intestine. Such fish were called "lungfish." They became the ancestors of all terrestrial animals.

For the known Green River Formation in the United States with numerous finds of fossil bony fish, see Wyoming.

The bone fins of the fish made a revolution - the fish made an attempt to reach land. The ichthyostega is the first amphibian whose ancestors were fish. In turn, the ichthyostega gave life to real amphibians - stegocephalous. Translated from Greek, "stege" is the roof, "cephale" is the head: "roof-headed."

Psylophytes are plants without leaves. Insects and arachnids emerge on land

Plants increasingly successfully conquered land, nature helped them in this by creating a root. The first plants were called psilophytes, which means "holoros" - they had no leaves.

Following the plants, insects and arachnids moved to land. For life on land, they acquired trachea.

390 million hp: Three plates - Lawrence, Baltic and Sibiria - connect to a large continent - Laurasia

About 390 million years ago, three plates - Lawrence, Baltic and Sibiria - successively collided with each other, connecting to a large continent - Laurasia.

380 million hp: The heart of shell fish is the oldest discovered in the world

In mid-September 2022, scientists from Curtin University discovered in Western Australia a perfectly preserved heart of ancient fish along with a fossilized stomach, as well as intestines and liver. The heart is 380 million years old and this is a record, and the find itself will help in the study of the evolution of jaw vertebrates. Scientists noted that the soft tissues of ancient species are rarely preserved.

According to a study published in the journal Science, the arrangement of organs in the body of arthrodirs, an extinct class of shell fish that flourished during the Devonian period from 419.2 million years ago to 358.9 million years ago, is similar to the anatomy of modern sharks, providing new evolutionary clues.

Exceptional in finding fish is that their soft tissue is preserved in three dimensions. In most cases, soft tissue is preserved in flattened fossils, where soft anatomy is nothing more than a spot on the stone.

The researchers used neutron beams and synchrotron X-rays to scan samples still in limestone nodules and constructed 3D images of soft tissues inside them based on varying densities of minerals deposited by bacteria and surrounding rock.

As a paleontologist who has been studying fossils for more than 20 years, I was really amazed to find a three-dimensional and perfectly preserved heart in 380 million ancestors! For the first time, we can see all the organs together in primitive jawfish, and we were especially surprised to learn that they are not so different from us, "said Kate Trinajstic, lead researcher and professor of paleontology at the University of Australia.

The results demonstrate for the first time a 3D model of a complex S-shaped arthrodir heart consisting of two chambers, with a smaller camera located on top. These features are considered advanced for such early vertebrates, offering a unique window into how the head and neck area began to change to accommodate the jaws, a critical step in the evolution of the human body.

The liver was large and allowed the fish to maintain buoyancy like modern sharks. However, scientists point to one critical difference. Some modern bony fish, such as lungfish and birch forests, have lungs that have evolved from swimming bubbles, but researchers have found no evidence of lungs in extinct shell fish. This suggests that modern lungs developed independently in bony fish at a later time.^[1]

374 and 359 million hp: Two stages of the Devonian extinction, the death of 50% of childbirth from radiation

About 374 and 359 million years ago, the so-called Devonian extinction occurred in two stages - the mass extinction of flora and fauna on Earth. It occurred at the end of the Devonian, one of the periods of the Paleozoic era. About half of all existing genera disappeared from the face of the Earth.

After the Devonian extinction, shell fish and jawless fish-like fish disappeared, with the exception of the mixin-like and lampreys.

and

After the Devonian extinction, when placoderms died out, bony and cartilaginous fish began to dominate the seas, which had no competitors.

Also at the end of the Devonian, the first labyrinthodonts appeared - a transitional form between fish and amphibians.

The hypothesis about the depletion of the Earth's ozone layer from star explosions

Such global extinctions are generally thought to be caused solely by terrestrial causes: for example, a volcanic eruption or an asteroid impact. But in 2020, scientists believe that the culprits of the Devonian extinction should not be sought on Earth, and not even in the solar system. Brian Fields, an astrophysicist at the University of Illinois, has conducted research with colleagues that suggests the exploding star^[2].

In their work, the researchers decided to consider a sharp decrease in ozone levels, coinciding in time with the Devonian extinction, as a consequence of astrophysical phenomena, and not a volcanic eruption or an episode of global warming. For example, radiation effects from a supernova explosion, or even several stars that were about 65 light-years away from Earth, may well have caused the ozone layer to deplete and eventually lead to disaster. And phenomena such as meteorite impacts, solar eruptions and gamma-ray bursts are short-term events and are unlikely to cause long-term destruction of the ozone layer, which caused the extinction.

Supernovae are a source of ultraviolet, X-ray and gamma radiation. After the explosion, the fragments collide with the surrounding gas, which causes the acceleration of photons. Thus, supernovae of stars after an explosion generate accelerated cosmic radiation, which is held for some time by a magnetic field inside the remains of the star. But it is able to reach the Earth and destroy its ozone layer, causing radiation damage to various life forms for about 100 thousand years.

Fossils found, for example, deformed spores of ancient plants, indicate a decrease in biodiversity in the Devonian period, which lasted about 300 thousand years and led to global extinction. This duration suggests the possibility of multiple supernova explosions, especially since giant stars usually form in clusters with other giants.

The authors of the study believe that the key to proving a supernova explosion will be the radioactive isotopes of plutonium-244 and samarium-146 (Pu-244 and Sm-146) in rocks and fossils formed during the Devonian extinction. They do not meet at all on Earth and could get here exclusively through space explosions. Now researchers have to find these isotopes in fossilized rocks formed at the junction of Devonian and Carboniferous.

Also in their work, scientists suggest that in the future, exploding stars could be life-threatening on Earth due to a possible combination of both instantaneous and delayed effects.

310 million hp: The connection of the continents of Laurasia and Gondwana forms the mainland of Pangea

About 310 million years ago, the connection of the continents of Laurasia in Gondwana forms the mainland of Pangea.

Pangea had unique climatic conditions. The interior of the continent was extremely arid due to mountain chains that prevent moisture from entering. However, coal deposits in the United States and Europe indicate that the equatorial regions of Pangaea were tropical forests resembling modern-day Amazonia. Coal deposits, in fact, indicate that there was a lot of life on land.

Climate models confirm that the central areas of Pangaea were dominated by drought, with occasional wet spells sometimes accompanied by flooding. The conditions Namibia resembled the modern or Lake Eyre basin in. Australia

The climate also influenced the distribution of animals. In the Late Triassic, reptile relatives - procolophonids - lived in temperate regions where it rained once a year, and synapsids (mammalian ancestors) lived in the tropics with seasonal monsoon rains. Restriction of movement of synapsids is due to their need in water-provided areas. In arid zones, reptiles had a competitive advantage due to metabolic features.

306 million hp: Ocean Paleo-Tethys

275 million hp

Various species of animals flourished in the vastness of Pangaea. In the Permian period, insects such as beetles and dragonflies, as well as the ancestors of mammals - synapsids - actively developed.

252 million hp: The largest Perm-Triassic extinction in history. Killed 96% of marine species and about 70% of terrestrial

The period of the existence of Pangea coincided with the largest mass extinction in history - Perm-Triassov. This event, known as the "Great Extinction," occurred about 252 Ma, destroying 96% of marine species and about 70% of terrestrial species.

251 million hp: The formation of Pangaea - the end of the Paleozoic and the beginning of the Mesozoic

Triassic

250 million hp: Mainland Siberia connects with Pangea to complete the formation of the supercontinent

About 250 million hp mainland Siberia connects with Pangea, completing the formation of supermaterics.

232 million hp

230 million hp: The appearance of the first dinosaurs

Main article: Dinosaurs

In the Triassic period between 243 million and 233.23 million years ago, the first dinosaurs appeared on Pangea, among which were theropods. These mainly predatory dinosaurs had hollow bones and feathers similar to those of modern birds.

225 million hp: The collapse of Pangea. Laurasia broke up into Eurasia and North America

As geologists know, supercontinents formations are unstable. Immediately after formation, the supercontinent tends to disintegrate. The reason for this is that the same mantle flows that bored the continents collided with them. Following the formation of the supercontinent, the lithosphere, which goes under it from all sides in the subduction zones, accumulates under it, and then floats up, splitting the supercontinent.

The Triassic period (250-200 million hp, this is the first period of the Mesozoic era) was just the time of the beginning of the split of Pangaea. The blocks of lithospheric plates that made up Pangea began to move away from each other. Africa and Eurasia began to move away from each other. The crushing of the continental bridge between Europe, Africa and America began.

When the continental blocks are separated from each other, the oceanic crust located between these blocks builds up (in fact, this is the extension). Growth occurs when a new crust is formed in the mid-ocean ridges.

Splits that occurred about 230 million years ago (between the Paleozoic and Mesozoic) formed new continents. Thus, Laurasia broke up into Eurasia and North America.

Yura

200 million hp: The beginning of the opening of the Atlantic Ocean

The discovery of the Atlantic Ocean began in the Early Jurassic (about 200 million years ago).

183 million hp: The beginning of the collapse of Gondwana in the southern hemisphere

183 million years ago (Mesozoic) Gondwana began to break up into two parts:

• west (Africa, Arabia and South America) and
• eastern (Australia, Antarctica, Madagascar and Hindustan), the border of which after 25 million years was the Strait of Mozambique.

179 million hp

175 mln hp: Formation of the Big Caucasus basin

Main article: Main Caucasian Range

The split of South America and Africa (with Arabia) led to an increase in the oceanic lithosphere between them and, which is very important for the Caucasus, to a reduction in the distance between Africa and Eurasia. The Tethys Ocean began to shrink in size.

Where the oceanic crust of the Tethys Ocean pushed hard under the edge of the Scythian Plate, this edge weakened. This is due to the fact that the ocean plate, going down, melts, and the excess of molten matter tries to break up.

Rifting began to occur on the weakened edge of the plate - the formation of rifts with the extension of the split fragments of the previous base. The new crust was expanding toward the ocean. The crust was generally continental, granite, but broken by outpourings of basalts. So (at the end of the Lower and beginning of the Middle Jurassic, something about 175 million hp) the so-called Big Caucasus basin was formed. It was a marginal sea. It was separated from the main ocean of Tethys by an island volcanic arc, the existence of which is also explained by the weakening of the lithosphere in the subduction zone, the sub-wave, and the breakthrough of magma to the surface with the formation of volcanoes. The Big Caucasus Basin was extended 1700-1800 km long and 300 km wide.

152 million hp

Chalk

137 million hp

125 million hp: East Gondwana split into Indigaskar and Australo-Antarctica. The emergence of the Indian Ocean

125 million years ago, East Gondwana split into Indigaskar and Australo-Antarctica, between which the Indian Ocean began to form.

100 million hp: South America separated from Africa. The emergence of the Atlantic Ocean

100 million years ago, South America separated from Africa, in the gap between which the Atlantic Ocean began to form.

94 million hp

90 million hp: The separation of Hindustan and Madagascar

90 million years ago there was a separation of Hindustan and Madagascar.

70 million hp

Mediterranean fold belt formed on the border of Gondwana and Laurasia

About 70 million years ago, the Mediterranean folded belt was formed in its modern form. It separates the southern group of ancient platforms, which constituted the supercontinent Gondwana until the middle of the Jurassic period, from the northern group, which formerly constituted the continent of Laurasia and the Siberian platform.

This belt includes the southern regions of Europe, Northwest Africa, Alps, Carpathians, Crimea, Caucasus, Persian mountain systems, Kopet Dag, Pamir, Himalayas, Tibet, Indochina and Indonesian islands.

An oceanic bottom has formed between Hindustan and Madagascar

India begins to move rapidly (according to geological ideas) to the north - 20 cm per year, while the usual speed of movement of plates is on average 1-2 cm per year.

Quetzalcoatli in North America

Quetzalcoatlus is one of the largest known members of the pterosaur order. The only species is Quetzalcoatlus northropi. Wingspan 10-11 meters.

Found in Late Cretaceous sediments of North America (habitat - about 70 million years ago).

66 million hp: Chicxuluba meteorite, which collided with the Earth in the area of ​ ​ the modern Gulf of Mexico, destroys 60% of biological species

There have been several mass extinctions on Earth. The last of them happened 66 million years ago at the boundary of the Cretaceous and Paleogene periods (K-Pg boundary) and led to the loss of about 60% of the planet's species, including non-avian dinosaurs.

The massive Chicxuluba meteorite, which collided with Earth in the area of ​ ​ the modern Gulf of Mexico, is believed to have played a key role in this extinction. The evidence for this theory is the high levels of platinum group elements (PGEs) such as iridium, ruthenium, osmium, rhodium, platinum and palladium in the K-Pg boundary layers, which are rare on Earth but often in meteorites. These elevated levels of PGE have been found around the world, suggesting that the impact has blown debris across the planet.

While some scientists speculate that an alternative source of PGE may have been large-scale volcanic activity from the igneous province of Deccan Trapps, still the specific PGE ratios at the K-Pg boundary are more consistent with asteroid impacts than volcanic activity. However, much in the nature of the Chicxulubian meteorite, in particular its composition and extraterrestrial origin, is poorly understood.

Paleogene

64 million hp: The collision of the Indian and Eurasian plates begins to form the Himalayas

The movement of the continents breakaway from Gondwana and their collision with parts of Laurasia led to active mountain formation. Africa's pressure on Europe resulted in the Alps, and the clash between Hindustan and Laurasia created the Himalayas.

The Indian Plate and Laurasia began unification approximately 65-63 million years ago, when the edges of the future Hindustan Peninsula began to sink under the Earth's crust in the central part of the current Tibet, Chinese geologists say in an article published in the journal Science China: Earth Sciences in 2017 ^[3]

"The India-Asia clash seems to have been the most powerful and interesting geological event in the last 500 million years. There are many traces of this process at the bottom of the ocean, but how this process began and how Tibet arose remains unknown to us due to the great complexity of this process, "said Ding Lin from the Institute for the Study of Tibet KAN in Beijing (China).

The question of when exactly Hindustan faced Laurasia is hotly debated among scientists. According to Lin, until recently, most geologists believed that this happened about 55 million years ago, when the Indian Plate touched Laurasia off the western shores of present-day Pakistan. Such claims are acutely opposed by other scientists, who believe that India could not move so quickly, having covered more than 2,000 kilometers in just 40 million years after separating from Gondwana. Therefore, they believe that the collision occurred noticeably later, 35 million years ago.

Lin and his colleagues, in turn, claim that the first touch of the Indian and Eurasian plates occurred even earlier than the supporters of the "Pakistani" hypothesis - 65 or 63 million years ago, and it happened in the region of central Tibet, and not off the coast of Pakistan. Chinese geologists came to this conclusion by analyzing data on the age of rocks at the "seam" connecting the Indian Plate and Asia and passing along the Yalutsangpo River, the source of the Brahmaputra.

According to scientists, the "traces" of the Earth's magnetic field in the oldest rocks of this seam indicate that it formed not 55 million years ago, as its western part in Pakistan, but at least 7-10 million years earlier, in fact, even before the dinosaurs died out. At this time, Hindustan and Eurasia were not yet a single land mass - even after the collision of the plates, they were separated by almost 1.3 thousand kilometers of water covering the underwater part of the Indian plate. Its immersion under Tibet, according to scientists, not only caused the birth of this plateau and the Himalayan mountains, but also caused powerful deformations and geological shocks throughout Eurasia. These geological changes in turn caused major climatic realignments in the region, depriving future Tibet of precipitation and spawning a humid monsoon climate with record rainfall levels in the summer season that characterizes India and Bangladesh today.

43 million hp: The mid-ocean ridge in the Indian Ocean stops expanding. Indian and Australian Plates Join in One Plate

The Indo-Australian plate was formed as a result of the merger of the then Indian and then Australian plates about 43 million years ago. The merger occurred when the mid-ocean ridge in the Indian Ocean, which separated the two plates, stopped expanding.

40 million hp: Demarcation of Australia and Antarctica

40 million years ago (during the Cenozoic era), the demarcation of Australia and Antarctica occurred.

35 million hp: The appearance of giant sloths

Main article: Ground (giant) sloths

30 million hp: The beginning of the formation of the East African fault

Main article: East African Fault (rift valley)

The separation of the African tectonic plate from the Arabian plate is a continuation of the decay of the supercontinent Gondwana and began about 30 million years ago. The space of the rift began to fill the water and the Red Sea was formed.

See also

• History
• Timeline of the Universe before the advent of planet Earth