Scientists announced Monday that it was not the asteroid impact that killed off the dinosaurs 66 million years ago, but debris ejected played a critical role.

The statement comes from a team led by the Royal Observatory of Belgium, which determined dust from pulverized rock was thrown into Earth’s atmosphere, blocking the sun and hindering the photosynthesis of plants.

New modeling showed that the amount of dust was about 2,000 gigatonnes – exceeding 11 times the weight of Mt. Everest – and lingered in the atmosphere for up to 15 years, causing a worldwide nuclear winter. 

Consequently, vegetation would have died off, resulting in the starvation of many herbivorous species, including some dinosaurs – kicking off the catastrophic mass extinction event that saw 75 percent of living creatures disappear from Earth.

Scientists announced Monday that it was not the asteroid impact that killed off the dinosaurs 66 million years ago, but debris ejected played a critical role

Scientists have been tirelessly working to unravel the mystery of the dinosaur extinction since the Chicxulub Crater was discovered in 1978.

However, the geological formation is not enough to conclude that the massive asteroid was enough to drive the dinosaurs to extinction.

The leading theory recently has been that sulfur from the asteroid’s impact—or soot from global wildfires it sparked—blocked out the sky and plunged the world into a long, dark winter, killing all but the lucky few.

However, research published Monday based on particles found at a critical fossil site reasserted an earlier hypothesis: that dust kicked up by the asteroid caused the impact winter.

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The particles were found at the Tanis fossil site in the US state of North Dakota.

Though 1,865 miles away from the crater, the site has preserved several remarkable finds believed to be dated from directly after the asteroid impact in sediment layers of an ancient lake.

The researchers said the dust particles were around 0.8 to 8.0 micrometers—just the right size to stick around in the atmosphere for up to 15 years.

Entering this data into climate models similar to those used for current-day Earth, the researchers determined that dust likely played a far more significant role in the mass extinction than previously thought.

Out of all the material shot into the atmosphere by the asteroid, they estimated that it was 75 percent, 24 percent sulfur and one percent soot.

Sean Gulick, a geophysicist at the University of Texas at Austin and not involved in the research, told AFP that the study was another interesting effort to answer the ‘hot question’—what drove the impact of winter—but did not provide the definitive answer.

He emphasized that discovering what happened during the world’s last mass extinction event was important for understanding the past and future.

‘Maybe we can better predict our own mass extinction that we’re probably in the middle of,’ Gulick said.