Mass extinctions: what are, causes and what are

To start, we must first know that The extinction of a species It occurs when there are no copies capable of reproducing and leaving offspring anywhere on planet Earth. Now, mass extinctions are one of the three Types of extinctions that exist. Let’s see how they are called and what are your differences:

• Background extinctions: They occur randomly in all groups of organisms and the loss of them is gradually produced.
• Mass extinctions: They cause a sharp decrease in the number of species that inhabit a certain geographical region and occurs in a certain period of time.
• Massive catastrophic extinctions: They happen instantly and global scale, as a result it drastically decreases the biodiversity of species.

In this other article you can learn more about the basic concept of species extinction: what is, causes and consequences.

After reading the previous section, you may ask yourself Why are mass extinctions or what are the causes of the mass extinction of the species. There are multiple causes that lead to the disappearance of species, but then we will tell you some of them.

Biological causes

Here the characteristics of the species and also the endemism and competition that may exist between them come into play. In this way, some species, especially invasive species in a territory, can displace other species, condemning them to extinction. In general, background extinctions occur due to these types of causes.

Environmental causes

Among the environmental causes are: changes in temperature, changes in sea level, changes in biogeochemical cycles, tectonic plaque movements, among others. On this occasion, if the species fails to adapt to the new living conditions, it is intended for extinction. For its part, volcanic activity is also part of environmental causes and, usually, these causes give rise to mass extinctions.

Extraterrestrial causes

We do not refer to Martians or UFOs, but rather the impact of asteroids and meteorites on the surface of the Earth. In this particular case, extinctions occur during and after the impact since after the impact can cause changes in the composition of the atmosphere, among other effects. Massive catastrophic extinctions, as it is believed that was the extinction of dinosaurs, happen by this type of causes.

Anthropogenic causes

They are those causes originated exclusively by the action of the human being. As an example, agricultural, mining, oil and forestry exploitation, environmental pollution, the introduction of exotic species, hunting and trafficking of wild species and also global warming are some of the environmental problems that the human being introduced into ecosystems and that, undoubtedly, leads to the extinction of species.

Can you imagine How many mass extinctions have occurred Through the history of the earth? With certainty there were five mass extinctions. Even many scientists say that we are going through the Sixth mass extinction. In this section we will tell you in which geological period each of the mass extinctions, its duration and their causes happened.

Ordovico – Siluric Extinctions

The first of the mass extinctions occurred approximately 444 million years ago. It is estimated that it lasted between 500 thousand to 1 million years and as a result more than 60% of the species were extinguished. There are several theories about the causes that produced this extinction, the most forceful states that it was because of the explosion of a supernova that produced changes at sea level and in the ozone layer.

Extinctions of the Devonic – Carboniferous

Approximately 360 million years occurred and more than 70% of the species were extinguished. This extinction event lasted 3 million years and it is believed that it began with the eruption of a mantélica pen or mantle pen, which are, deep columns that come from under the earth’s crust and that originate hot points and volcanic areas.

Permian – Triassic extinctions

This event happened around 250 million years ago and lasted for a million years. As a balance, 95% of marine species and 70% of terrestrial species disappeared. The causes are not known exactly, but it is estimated that it may have been due to volcanic activity, gase release from the land core and impact of an asteroid.

Triassic – Jurassic Extinctions

260 million years ago, this mass extinction event occurred that extended for one million years and ended 70% of the species. Among the theories that explain its causes are the fragmentation of the great Pangea continent and also successive volcanic eruptions.

Cretaceous – Tertiary Extinctions

It happened 66 million years ago and perhaps it is the most known species mass extinction event, because in it the species of dinosaurs that inhabited the Earth were extinguished. There are multiple theories that explain the causes, the main ones are based on high volcanic activity and the impact of a large asteroid. The curious thing about this event is that it not only ended the dinosaurs but also with more than 70% of the species and it is estimated that it lasted only 30 days.

We recommend you read this other Ecology post about why dinosaurs were extinguished. You can also know them a little better reading these articles about herbivorous dinosaurs: names, types, characteristics and images and carnivorous dinosaurs: names, types, characteristics and images.

Holocene extinctions or the sixth mass extinction

This particular event generates numerous controversies, not only because it would be happening right now but also because its causes are merely anthropogenic. The truth is that since the development of human activities, the species extinction rate is largely increased and, for example, the mammalian extinction rate is 280 times higher than normal rates. In addition, it is estimated that extinct species in the last two centuries (200 years) should have been extinct in 28,000 years. Given this, it is more clear that we are facing the sixth mass extinction of species.

To finish knowing these mass extinctions in the history of the planet, we leave you here a Mass extinction timeline.

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