(ORDO NEWS) — After the giant 12-kilometer asteroid that formed the famous Chicxulub crater fell to Earth at the end of the Cretan period, 66 million years ago, “dark times” began on our planet. As a result of numerous forest fires, huge amounts of soot rose into the air, and darkness came to the Earth.
To reconstruct the chronology of these events in a new study, scientists modeled the extinction of species from the Cretan period, changing the duration of the “dark age”.
Only in the last decade have scientists been able to develop computer models assessing the effect of the duration of the dark period on the Earth’s surface on the survival of organisms, said the lead author of the new study, Peter Roopnarine, curator of the geological direction of the Department of Invertebrate Zoology and Geology, California Academy of Sciences, USA.
“It is generally believed that global wildfires were the main source of soot in the atmosphere,” Rupnarin said. “The concentration of soot in the air in the first few days or weeks was high enough to suppress photosynthesis.”
In their study, Runarin and colleagues modeled the effects of long-term exposure to darkness on ecosystems that existed at the time of the impact. They used a set of 300 species from the late Cretan Hell Creek Formation in the United States.
In their work, the authors changed the duration of exposure to low light from 100 to 700 days and assessed the percentage of species survival.
According to the work, ecosystems were restored only if the duration of darkness on the planet did not exceed 150 days. After 200 days, irreversible extinctions and changes in the dominance of species began. If darkness persisted on the planet for 650 to 700 days, the proportion of extinct species ranged from 65 to 81 percent, which is close to the actual value of 73 percent for the Hell Creek Formation. This means that in this area of the planet’s surface, the “dark era” was about 2 years, the authors concluded.
The work was presented at the annual meeting of the American Geological Union in New Orleans.
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