Asteroid that killed the dinosaurs ignited massive wildfires

At the end of the Cretaceous Period, about 66 million years ago, a massive asteroid struck the Yucatan Peninsula in what is now Mexico, and triggered a mass extinction that wiped out the dinosaurs, along with over 75 percent of all living species. While scientists have long known that this catastrophic impact caused devastating wildfire that contributed to this mass extinction, how and when these wildfires started remained a mystery.

Now, an international team of researchers from Mexico, Brazil, and the United Kingdom has found that the asteroid that hit the Earth almost instantly ignited wildfires up to thousands of kilometers from its impact zone.

“Until now it has not been clear whether the fires were caused as a direct result of the impact or subsequently, as vegetation killed by the post-impact darkness caused by the debris thrown up into the atmosphere was set ablaze by things such as lightning strikes,” said study co-author Ben Kneller, an expert in Geosciences at the University of Aberdeen.

By analyzing rocks dating to the time of the asteroid strike, Dr. Kneller and his colleagues discovered that some of the wildfires broke out within minutes from the impact, in areas stretching up to 2,500 kilometers from the impact crater. The wildfires that were ignited in coastal areas were short-lived, since the backwash from the mega-tsunami caused by the impact swept charred trees offshore.

An analysis of the fossilized tree barks showed that the fires had already begun by the time the trees were washed away soon after the initial impact. According to the scientists, this was either due to an enormous fireball caused by the asteroid strike, or by the heat from droplets of melted rock falling back through the atmosphere in the immediate aftermath of the impact.

“Ultimately our research confirms how and when these devastating fires were begun and paints a vivid and quite terrifying picture of what happened in the immediate aftermath of the meteorite strike,” Dr. Kneller concluded.

The study is published in the journal Nature Scientific Reports.

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By Andrei Ionescu, Earth.com Staff Writer