Why did 75% of the species that inhabited the Earth disappear after the fall of an asteroid?

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A group of researchers from the United States conducted a study in which a new hypothesis was proposed to explain the reasons that contributed to the mass extinction of the 75% of the species that inhabited the Earth (among them, plants and non-avian dinosaurs) after an asteroid impact made 66 million years, publicly the specialized medium Live Science.

The catastrophic event led to a period of total darkness that lasted for about two years. This was due to the formation of clouds that contained rock dust that was expelled into the atmosphere when the asteroid collided with the Earth’s surface, causing the ecosystem to completely collapse. due to the drop in temperatures, which has cooled the planet. at a drastic speed.

The model proposed by the scientists indicates that the clouds were also composed of sulfuric acid, which caused acid rain all over the world, causing a large number of forest fires. “The common thought is now that global wildfires would have been the main source of fine soot that would have been suspended in the upper atmosphere,” said California Academy of Sciences paleontologist Peter Roopnarine.

Roopnarine commented that “the soot concentration during the first days or weeks of the fires would have been high enough to reduce the amount of incoming sunlight to a level low enough to prevent photosynthesis.” The research team studied the long-term impact of this period of Earth’s darkness by reconstructing ecosystems that may have existed before the asteroid impact.

For this, they used 300 species from a region rich in fossils and elements belonging to the Cretaceous period, the so-called Hell Creek Formation (known as “Arroyo del Infierno” in Spanish), which extends to through the states of Montana, Wyoming. , North Dakota and South Dakota.

After a series of simulations carried out by the researchers, in which they exposed this group of species to long periods of darkness of between 100 and 700 days in order to find out in which interval of darkness their extinction would occur. Fossil records show that the 73% of vertebrates have disappeared following the catastrophic event.

The post-impact darkness period began quickly after a few weeks, Roopnarine said. Scientists have discovered that ecosystems could recover if the period of darkness only lasted 150 days, but if it was extended to 200 days, it would cause extinction of certain species and the predominance of those that managed to survive, causing serious damage to the ecosystem.

When the dark interval is prolonged until the 700 days, extinction levels increased from 65% to 81%. According to the simulation, this was the fate of the species “Hell Stream” after two years in total darkness, after conditions in the world changed due to atmospheric flux and there was a large variation in temperature levels.

Likewise, the study concluded that the Hell Creek Formation species group that survived in the absence of light for 700 days it took about 40 years to recover once this anomaly has been resolved, reported scientists at the American Geophysical Association (AGU) Fall Meeting.

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