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¿Por qué desaparecieron el 75 % de las especies que habitaban la Tierra después de la caída de un asteroide?

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


24 dic 2021 13:57 GMT

An investigation analyzed about 300 species belonging to the Cretaceous period, which were exposed to a period of artificial darkness in a simulation.

A group of researchers from the USA conducted a study in which a new hypothesis was proposed to explain the reasons that contributed to the mass extinction of animals. 75% of Earth-dwelling species (including plants and non-avian dinosaurs) After the impact of an asteroid impact 66 million yearsAnd publicly Live Science Specialist Broker.

The catastrophic event led to a period of complete darkness that lasted nearly two years. This was due to the formation of clouds that contained rock dust that was expelled into the atmosphere at the time of the asteroid’s collision with the Earth’s surface, causing the complete collapse of the ecosystem due to lower temperatures, which led to the cooling of the planet. Very quickly.

The model proposed by scientists indicates that the clouds were also composed of sulfuric acid, which caused acid rain around the world, which caused a large number of wildfires. “The common thinking now is that global wildfires would have been the main source of fine soot that would have been suspended in the upper atmosphere,” explained California Academy of Sciences paleontologist Peter Rubinaren.

“The soot concentration in the first days or weeks of fires was high enough to reduce the amount of incoming sunlight to a low enough level to prevent photosynthesis,” Rupnarin commented. The research team studied the long-term impact of this period of terrestrial darkness by reconstructing ecosystems that may have existed before the asteroid impact.

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For this they used 300 species from an area of ​​land rich in fossils and elements belonging to the Cretaceous period, the so-called Hell Creek Formation (known as Arroyo del Infierno in Spanish), which stretches across the states of Montana, Wyoming. North Dakota and South Dakota.

After a series of simulations by the researchers, they exposed this group of species to long periods of darkness ranging from 100 to 700 days in order to discover which period of darkness their extinction would occur. Fossil records show that 73% of vertebrates became extinct result of the catastrophic event.

The period of darkness after the effect began quickly after a few weeks, Robbenarin said. Scientists have found that ecosystems can recover if only darkness lasts 150 days, but if it is extended to 200 days, that would cause extinction Some species and the dominance of those that have managed to survive, causing massive damage to the ecosystem.

When the interval stretched from darkness to 700 daysextinction levels increased from 65% to 81%. According to the simulations, this was the fate of the Hell Stream species after two years in complete darkness, after conditions around the world changed due to the influx of the atmosphere and there was a strong contrast in temperature levels.

Similarly, the study concluded that the group of species from the Hell Creek Formation that survived in the absence of light during 700 days took around 40 years to recover After this anomaly dissipated, mentioned Scientists at the fall meeting of the American Geophysical Society (AGU).

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