Study offers new explanation for demise of dinosaurs after asteroid impact

A new study indicates that the Everest-sized asteroid that slammed into a shallow sea near current-day Yucatan 66 million years ago propelled many tons of fine dust into the atmosphere, dust small enough to stay aloft for years, which some scientists believe to be the best explanation for why the dinosaurs and three-quarters of all other life on Earth quickly died.

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The reason for the mass extinction caused by what is now called the Chicxulub asteroid has long been a subject of scientific debate, CNN reported.

The most recent theories blamed a massive release of sulfur and soot from wildfires for a cataclysmic global winter, dropping temperatures so low that only about 25% of all life survived. Dinosaurs were unable to live in the new, cold environment, according to a report on the new findings in the scientific journal Phys.org.

The new study, published last Monday in the journal Nature Geoscience, found that the impact produced fine silicate dust that was pulverized into such tiny particles that it was able to float in the atmosphere for 15 years, darkening the sky for about two years — long enough to stop the process of photosynthesis. As the plants died off, the plant-eating animals that fed on them starved, and the animals who fed on the plant-eaters died soon after, leading to the catastrophic extinction event.

The fine silicate from pulverized rock would, along with the sulfur and soot, have dropped global temperatures by 15 degrees Celsius, the researchers said.

“Photosynthesis shutting down for almost two years after impact caused severe challenges (for life),” said lead study author and planetary scientist Cem Berk Senel, a postdoctoral researcher at the Royal Observatory of Belgium, according to CNN. “It collapsed the food web, creating a chain reaction of extinction.”

The study also suggested that the dinosaurs who evolved into birds, crocodilians and small mammals survived because they were generally much smaller than most animals on Earth and didn’t require as much nutrition while the plant life slowly recovered.