5 terrifying mass extinctions in Earth's history

Go back in history to learn about the 5 Great Extinctions on Earth and find the answer to the 6th Great Extinction.

Throughout its 4 billion year history, the Earth has undergone countless changes, and all of these changes have contributed to creating the wonderful living planet we have today.

There was a time when the Earth seemed to have reached the end of the world when it went through many “unpleasant changes” of nature. But in the end, the Blue Planet still proved its strong vitality when it still stood firm after 5 Great Extinctions…

1. Ordovician-Silurian extinction

This was the first mass extinction, occurring 440 - 450 million years ago. During this period, many consecutive extinctions occurred, destroying 17% of families, 50% of genera and is considered the second largest extinction in history in terms of the number of species destroyed.

By the time the Ordovician period ended, about 49% of marine animal genera had disappeared completely, and other animal phyla were also in decline. To date, the most widely accepted hypothesis for the cause of the extinction is that a gamma-ray burst from a star near Earth caused a sharp drop in atmospheric carbon dioxide. This affected the Earth, creating an ice age that lasted 0.5 - 1.5 million years.

The periodic rise and fall of sea levels through successive ice ages created many ecological niches on the continent. Biodiversity gradually declined, especially species with restricted habitats on the continental shelf and in the tropics were also greatly affected.

At the end of the era, the melting glaciers caused sea levels to rise. From here, the surviving families and orders began to recover, and with it, biodiversity increased, opening a new era.

2. Devonian extinction

There is archaeological evidence that this was a mass extinction that may have lasted for 20 million years. The extinction began about 360 million years ago, just before the transition from the Devonian to the Carboniferous period.

Before the extinction, the continents were home to lower plants and the first insects, while the oceans were dominated by giant coral reefs and a dramatic evolution of fish was taking place.

According to paleontologist McLaren, a large meteorite collided with Earth, causing tsunamis, devastating coastal ecosystems, and disrupting deep-sea floors.

Another reason is that the strong growth of plants has reduced CO2, making the climate colder, many creatures that could not adapt were destroyed.

Marine life was the main victim: coral reefs - home to marine life - died off en masse, leading to the extinction of many species. An estimated 19% of families, 50% of genera and 70% of species were lost in this extinction.

3. Permian - Triassic extinction

This was the most terrible extinction event in history, wiping out most of the creatures on Earth, resetting almost the entire ecosystem. Paleontologists say that more than 90% of marine life and 70% of terrestrial life were completely wiped out.

Archaeological evidence shows that the main cause of the above phenomenon is the strong tectonic movement of the Earth's crust, causing cracking and compression of continental plates.

The eruption of magma on the surface of the Earth engulfed everything in a sea of ​​fire. In addition, dust and carbon dioxide filled the air, causing a greenhouse effect that made the Earth hotter than ever. Under the ocean, changing ocean currents caused many ecosystems to disappear, making life extremely fragile.

Another cause believed to have contributed to this bloody mass extinction was the collision of a 500km-radius asteroid with the Earth. Traces of this collision were found in Antarctica in 2006 by scientists from Ohio State University, USA.

It took a long time for life to gradually return from the lucky survivors, including some groups of reptiles.

4. Triassic - Jurassic extinction

This extinction marked the boundary between the Triassic and Jurassic periods, occurring 199.6 million years ago. This mass extinction had a profound impact on life on land and in the oceans.

Many marine vertebrates and marine reptiles disappeared, with the exception of ichthyosaurs and copepods. Invertebrates such as brachiopods, molluscs, amphibians and especially the archosaurs (excluding dinosaurs) on land were also severely affected. About 23% of families and 48% of genera became extinct.

It is still uncertain what caused the end-Triassic extinction event. Scientists speculate that a major volcanic eruption occurred. However, recent studies have pinpointed the exact time of the extinction and the meteor impact that created Lake Manicouagan (Canada). This evidence suggests that the impact may have been the direct cause of the extinction.

The extinction event wiped out many of the Earth's large animals, allowing dinosaurs to dominate the planet throughout the Jurassic and Cretaceous periods. Dinosaurs ruled the land, while freshwaters were the domain of the ancestors of today's crocodiles (a subclass of lizards), plesiosaurs, and ichthyosaurs, which became the kings of the sea.

The extinction ushered in the heyday of reptiles with the dominance of dinosaurs.

However, when the age of reptiles was extremely prosperous, the Earth encountered the next disaster - the Cretaceous - Paleogene mass extinction.

5. Cretaceous - Paleogene extinction

This extinction event occurred at the end of the Cretaceous period about 66.5 million years ago, marking the end of the Mesozoic Era and the beginning of the Cenozoic Era with the Paleogene period. About 17% of families, 50% of genera, and 75% of species became extinct after this event.

Based on archaeological evidence accumulated through research, scientists hypothesize that this extinction event was caused by one or more simultaneous disasters, such as the strong impact of a meteorite (creating the Chicxulub craters in Mexico, Boltysh in Ukraine) or by falling sea levels, strong volcanic eruptions creating the phenomenon of "Deccan traps" seriously destroying the Earth's biosphere.

These geological events reduced the amount of sunlight and the rate of photosynthesis, leading to the destruction of the Earth's ecosystem on a large scale. The climate became drier, and the food chain was also disrupted.

Dinosaurs were the first vertebrates to be affected by environmental change, species diversity decreased significantly. Along with that, some plants and invertebrates also disappeared from Earth, creating conditions for mammals to develop and gradually dominate.

The Cretaceous-Paleogene extinction was uneven. Some organisms went extinct completely, others were severely affected, and others were barely affected.

6. Will there be a 6th Mass Extinction?

All extinctions in history are caused by nature, occurring in cycles. Each collapse simultaneously opens a new era, creating conditions for the development of many creatures with strong vitality. The question that scientists ask is, will the 6th mass extinction appear?

And in fact, it is showing signs of beginning… This time it is not nature anymore, but humans who are committing “suicide”. It will not be volcanic eruptions, meteorite collisions, sudden changes in sea levels, but environmental pollution, habitat degradation, ecological imbalance, climate change…

The current rate of extinction is 4,000 times faster than that of the dinosaurs. All human impacts have left serious consequences for nature, which are difficult to recover. Overexploitation of resources without conservation and preservation has gradually destroyed the life of all living things.

Scientists predict that if the situation continues, in less than a century, a mass extinction will officially begin, and humans will suffer the same fate as the dinosaurs. But after that extinction, will humans be lucky enough to survive and life be restored?

According to khoahoc.tv