The mystery of the 11 mass extinctions on Earth and the prediction of the 12th event

Up to the present time, doomsday events still contain countless mysteries that humans have not been able to fully discover, followed by signs of a "possibly" great danger in the middle of the world. modern world.

Massive extinctions appeared on Earth

Earth has witnessed a series of terrifying doom events throughout its history. Experts estimate that of the 4 billion species of organisms that have evolved on the 'blue planet', about 1% can still maintain the species until now.

However, the above estimate is still too 'vague' and somewhat 'optimistic'. Because fossilization is a unique and rare process, "less than 1/10 of 1%" of all species that have ever existed have become fossils.

Through studying the fossil source found, scientists can determine the origin and evolution of different species of organisms. Although part of the natural cycle, mass extinction events still cause terror to all living things because they can lead to biodiversity loss, or worse, the extinction of all life on Earth. soil.

1. Oxygen disaster

While oxygen is an essential part of human life, the birth of this 'life source' was in fact the cause of the first mass extinction in Earth's history known as the Oxidation Event. Large Mass (GOE), also known as Catastrophe Oxygen, a simple chemical element that has drastically changed the course of life on our planet.

After the GOE takes place, excess free oxygen begins to accumulate in the atmosphere.

About 3 billion years ago, Earth's atmosphere had only 0.03% oxygen content of what it is today. Anoxic bacteria do not need oxygen to survive, in fact, oxygen with them is extremely toxic. This turned out to be detrimental when cyanobacteria (Cyanobacteria) appeared.

In the beginning, any free oxygen produced is chemically captured by dissolved iron or organic matter (i.e. oxidizing those substances). When these substances are exhausted, free oxygen begins to accumulate in the environment, and this is the beginning of GOE.

After the GOE takes place, excess free oxygen begins to accumulate in the atmosphere. Free oxygen is harmful to anaerobic organisms and, when concentrations were high, may have wiped out most of the anaerobic 'inhabitants' of the Earth at the time. These cyanobacteria are therefore responsible for one of the largest extinction events in Earth's history.

Eventually, aerobic organisms begin to grow, consuming oxygen and leading to an equilibrium of atmospheric oxygen. Since then free oxygen has been an important component of the atmosphere. Today, cyanobacteria only exist in low-oxygen places like the ocean floor.

2. 50% of life on Earth disappeared in the Cambrian period

Between the last phase of the Cambrian, which lasted from 541 million years to 485 million years ago, Earth witnessed two extinction events known as the last Botomian mass extinction events.

The Cambrian is considered an important timeline in Earth's biological history because of the transition from unicellular organisms to multicellular organisms, including shellfish such as trilobites. . However, about 510 million years ago, experts estimate that 83% of all hard-shelled genera around the world went extinct.

The Cambrian is considered an important timeline in the biological history of the Earth.

After the mass extinction event, global biodiversity is thought to have dropped to as low as 35%. Organisms such as trilobites and archaeocyathids (Ancient Grail animals) were "severely affected".

To some scientists, the last Botomian mass extinction event is considered even more severe than the extinction at the end of the Permian period, some 250 years later.

However, scientists are still not entirely sure what caused the last Botomian mass extinction event. According to the University of Leeds, there are several theories, including volcanism, rising sea levels, oxygen-depleting oceans, and more.

3. Ordovician Great Extinction

The Late Ordovician mass extinction includes two extinction events during the Hirnantian period, the last of the Ordovician about 444 million years ago, and is considered one of the largest extinction events in the biological history of the Earth. soil. During the "two pulses of extinction", 85% of all marine species became extinct, along with 85% of all species, 60% of all genera, and 25% of all families.

During the "two pulses of extinction", 85% of all marine species became extinct.

The first mass extinction on Earth occurred at a time when organisms such as corals and shellfish arthropods filled the world's shallow waters but had yet to venture to land. Life itself has begun to spread and diversify, first appearing around 3.7 billion years ago. But about 440 million years ago, a climate change caused sea temperatures to shift, and much of the life in the ocean died out. At the end of the Ordovician, mass glaciations covered the southern supercontinent, Gondwana.

Freezing on this scale has stripped away high proportions of the world's water and dramatically lowered global sea levels, depriving them of vital habitat, according to a study published in the journal Oceanology. species, destroying the food chain and reducing fertility, according to a study published in the journal Oceanology.

However, not all scientists agree with this. According to National Geographic, other theories suggest that the toxic metal may have dissolved into seawater during periods of oxygen depletion, wiping out marine life.

Other scientists suggest that a gamma-ray burst from a supernova ripped a giant hole in the ozone layer, allowing deadly ultraviolet radiation to kill life below. According to APS News, there is another theory that volcanoes are to blame.

4. Lau event

About 420 million years ago, the Lau event (Kozlowskii), was the last of three extinction events that occurred during the Silurian period, after the "brothers" Ireviken and Mulde. other series - having "closely linked" with factors such as volcanic eruptions, experts have many difficulties to determine the cause of Lau.

The Lau event is the last of three extinction events that occurred during the Silurian period.

According to Science Daily, 23% of marine life was wiped out during the extinction phase in Lau. Interestingly, coral reefs in shallow waters are mostly unaffected. Scientists believe that this is due to the deoxygenation of the ocean starting to happen to creatures living in the deep sea. It is also believed that "an increase in sulfur in the ocean" also contributed to this 'purge'.

Mass extinctions and "graves of large amounts of organic matter" are also thought to have led to a disruption of the carbon cycle, causing dramatic changes in the climate and environment of the time. However, because the carbon cycle disruption occurred more than 100,000 years after the Lau extinction event, it is difficult to prove whether there is indeed a link between them.

5. Late Devonian Extinction

Although scientists agree that the extinction event at the end of the Devonian era wiped out countless different species, there are still mixed opinions about how long the "conquest" lasted. The Devonian period itself spanned from 419 million years ago to 358 million years ago, and mass extinctions are thought to have lasted from 2-4 million years to 20-25 million years.

The main victims of this destructive event were marine life and coral reefs.

According to The Devonian Times, during 8 to 10 extinction events during the late Devonian mass extinction, 20% of all animal families and 70-80% of all official animal species 'evaporated' " from the surface of the Earth.

The main victims of this destructive event were marine life and coral reefs, leading to dramatic changes in coral reef ecosystems. The American Museum of Natural History once wrote: 'Corals in general have been so badly affected that it takes them almost 120 years to recover and regenerate'.

According to paleontologist McLaren, a large-diameter meteorite has collided with Earth, causing tsunamis, devastating coastal ecosystems, and disturbing the deep sea layers. Another reason is that the strong growth of plants has reduced CO2, causing the climate to become colder, many organisms that cannot adapt have been destroyed.

Discover magazine writes that scientists believe most extinctions during the late Devonian mass extinction were caused by low oxygen levels in the oceans, but they are still unsure exactly why there is oxygen present. was so low during that period.

6. The collapse of the carbon rainforest

While the history of mass extinctions has often focused on animal species, the mass extinction of once-forgotten flora was somewhat 'smaller' than that of other 'terminators'. Known as the 'Collapse of the Carboniferous Rainforest', the mass extinction of plant species about 307 million years ago is thought to have radically altered the landscape and ecology of The earth.

Vegetation during this period initially flourished due to its moisture-loving nature.

According to The Conversation, about 310 million years ago, the land of Pangea and Cathaysia was covered with vegetation similar to tropical rainforests. These forests are known as "coal forests" because when the plant matter from these forests decomposes, huge deposits of peat accumulate, which are later turned into coal.

Discover magazine reports that even the word "Carboniferous" (original name) means "contains coal" in Latin. Vegetation during this period initially flourished due to its moisture-loving nature, however, as the Earth's climate became increasingly arid, many plant species such as horsetail and ground pine gradually disappeared. . Until now, the extent and overall scale of this mass extinction remained a mystery.

7. Permian - Tam Diep: The bloodiest massacre in Earth's history

The Permian - Triassic extinction event, or more commonly known as the P - T event, is considered the most terrible Great Extinction in the biological history of the Earth. Also known as the 'Great Dying', many scientists believe that the P-T's destruction level is 'invincible', no mass extinction event can ' put on the scale" with it.

The main cause of this phenomenon is the strong tectonic movement of the Earth's crust

Taking place about 251.9 million years ago, this mass extinction wiped out 90% of marine life and 70% of terrestrial life, establishing almost the entire biological system. All life on Earth today is the source of only about 10% of the animals, plants, and microorganisms that survived the Permian mass extinction.

Archaeological evidence shows that the main cause of the above phenomenon is the strong tectonic movement of the Earth's crust, causing fractures and compaction of continental plates. The eruption of magma to the surface of the Earth engulfed them all in a sea of ​​fire. Besides, dust and carbon gas fill the air, causing a greenhouse effect that makes the Earth hotter than ever. Under the ocean, the changing ocean currents have disappeared many ecosystems, life becomes extremely fragile.

Another cause that is thought to contribute to this bloody mass extinction is the impact of a meteorite with a radius of 500 km with Earth. It is estimated that the process of recovery and regeneration after the sweep took up to 10 million years.

8. The End of the Triangle - Jurassic

After the terrible impact of P - T on Earth, life only had about 50 million years before another mass extinction event struck. The Triassic-Jurassic extinction, also known as the Late Triassic extinction, occurred about 201 million years ago and has been described as "about the same size as the Late Ordovician, Late Devonian events and the end of the Cretaceous".

Many species of marine vertebrates and marine reptiles have disappeared.

Experts estimate that up to 34% of marine genera have become extinct. Many species of marine vertebrates and marine reptiles have disappeared, with the exception of fish lizards and flippers. Invertebrates such as phylum, molluscs, amphibians and especially reptiles, subclass of ancient lizards (except dinosaurs) on land were also severely affected. About 23% of them, 48% of the genera are extinct.

At the end of the Triassic period, the Earth warmed, likely due to the massive amounts of greenhouse gases being pushed into the atmosphere by the Mid-Atlantic Magma Zone, whose lava deposits could cover the United States. The increase in CO2 has acidified the oceans and made it harder for marine organisms to build shells from calcium carbonate (CaCO3).

This destructive event allowed dinosaurs to dominate the planet during the Jurassic and Cretaceous periods. Dinosaurs dominated the entire land, while the freshwater areas were the territory of the ancestors of today's crocodiles (under the lizard subclass), snake-necked lizards and fish lizards became kings of the sea. .

9. Meteorite 'fate' of Cretaceous - Ancient Near

The Cretaceous - Paleozoic extinction event, formerly known as the K-T extinction, may be considered the best known extinction event in Earth's history. The above extinction refers to the asteroid impact that occurred about 65 million years ago, which resulted in the evaporation of most life on Earth, including the dinosaur dynasty.

The above extinction refers to an asteroid impact that occurred about 65 million years ago.

The asteroid Chicxulub, about 12 km wide, crashed into Earth in the waters off the Yucatán peninsula of present-day Mexico at an estimated speed of 70,000 km/h. It not only left a crater more than 190 km wide, but also caused a huge tsunami and burned every forest on any land within nearly 1,500 km of the impact, creating the phenomenon 'Deccan trap' severely damaged the Earth's biosphere.

Those geological events sent dust and debris into the atmosphere, leading to global cooling and the near-instant collapse of ecosystems. The tragedy led to the eradication of about 76% of the world's biological species, marking the end of the Mesozoic and the beginning of the Cenozoic with the Paleogene.

10. Eocene – Oligocene 'cold shock'

About 34 million years ago, when the Eocene epoch ended, the Earth's climate cooled suddenly, impacting biological life with a mass extinction known as the Eocene extinction event – Oligocene. As temperatures plummet, forests turn to grasslands, sea levels drop and mark the formation of an ice sheet that covers the whole of Antarctica.

For some organisms, the Eocene - Oligocene extinction event was even more devastating.

Scientists estimate that in Europe and Asia, nearly 66% of all species have become extinct, and that 63% of mammal species in Africa and the Arabian Peninsula are completely extinct. disappear. For some organisms, the Eocene - Oligocene extinction event was even more devastating. Only 10% of the mollusk species in the coastal plains of the US flatter area survived in the Oligocene (Tien Tan)

The 'Annals of Botany' writes that the cooling of the Earth's climate is attributed to changes in ocean currents, changes in tectonic plates, and a decrease in atmospheric carbon dioxide. and "reduced insulation".

11. 'Farewell' to the 'giant monsters'

Until 3 or 4 million years ago, Megalodon - a giant super shark that once dominated the oceans, at the top of the food chain under the sea. However, after the extinction at the Pliocene-Pleistocene boundary, about 2.6 million years ago, animals of such enormous size were wiped out from the world's oceans, including Megalodon.

About 36% of marine species are estimated to be extinct. Some scientists have theorized that a supernova, which covered the Earth's surface with a rain of muons, causes cancer and mutations - especially in large animals and giant. It is suggested that the cause comes from sea level change and the narrowing of coastal habitats.

Megalodon super shark teeth.

12. The 12th genocide: Is there a chance for humanity?

Most scientists agree that the Earth is going through a mass extinction event, but there is some disagreement about the outcome and whether it is cause for concern. Called the Holocene extinction, this extinction is different from other 'forerunners' due to human impact.

A 2017 study claims the 'biological extinction' of wildlife in recent decades has caused a sixth mass extinction and says the Earth is headed for a 'crisis' Global'. Scientists warn that human consumption and indiscriminate destruction are the reasons for this event. This could be the first mass extinction since the time of the dinosaurs. Currently about 41% of amphibians and more than a quarter of mammal species are threatened with extinction.

There are an estimated 8.7 million plant and animal species on our planet, with about 86% of terrestrial species and 91% of marine species still undiscovered. Of the species we know, 1,204 species of mammals, 1,469 species of birds, 1,215 species of reptiles, 2,100 species of amphibians and 2,386 species of fish are endangered.

And yet, also under threat are 1,414 insects, 2,187 molluscs, 732 crustaceans, 237 corals, 12,505 plant species, 33 fungi and 6 brown algae. More than 25,000 species of the 91,523 species assessed in the 2017 'Red Book' update have been classified as 'threatened'. The number of endangered invertebrates has also peaked. Another study found that 70% of all vertebrates had disappeared within 50 years from 1970.

Scientists predict insect species could become extinct within 100 years as a result of crippling population decline. They fear that the dawn of the mass extinction coincides with the beginning of the Anthropocene - a geological age defined by human activity with dominant influences on climate and the environment. school.