Dino-killing asteroid sparked global fires, scientists believe

Computer-generated image of the Chicxulub impact crater

(CNN) -- A giant space rock that hit the Earth eons ago scattered high-velocity rubble over the planet, setting off wildfires that quickly spread over much of the equatorial region, North America and the Indian subcontinent, scientists announced this week.

The instant inferno, thought to have hastened the end of the dinosaurs, could have spared Europe, northern Asia, Antarctica and much of Australia, according to David Kring of the University of Arizona and Daniel Durda of the Southwest Research Institute.

The duo, who speculated that the mega-blazes needed only several days to spread around the world, said the horrific scenario followed the impact of a big space boulder in Chicxulub, Mexico.

"The fires were generated after debris ejected from the crater was lofted far above the Earth's atmosphere and rained back down over a period of about four days," Kring said.

HOT PLANET Animated world map shows spread of dino-killing wildfires  (Courtesy Kring/UofA/ Durda/SWRI)   EXTRA INFORMATION Impact-Generated Wildfires Full report from Kring and Durda

"Like countless trillions of meteors, the debris heated the atmosphere and surface temperatures so intensely that ground vegetation spontaneously ignited."

An immense impact crater lies beneath the site in the Yucatan Peninsula. The blast, which took place 65 million years ago, heralded the end of the Cretaceous Period.

More than three-quarters of the plant and animal species on the planet did not survive the transition to the Tertiary Period, when mammals replaced dinosaurs as the dominant species.

The collision unleashed an estimated 10 billion times more energy than did the atomic bombs dropped on Japan, the scientists sadi.

Some debris concentrated around the impact site and more drifted westward over the spinning Earth and concentrated on the opposite side around India, the researchers said.

"The material was launched around Earth," Kring said. "Then, because the Earth rotates, it turned beneath [the] plume of debris and the fires migrated westward. That's what caused the wildfire pattern."

The study, published in the Journal of Geophysical Research, elaborates on rudimentary climate wildfire models developed by University of Arizona planetary scientist Jay Melosh and others.

"We've added more detail in re-evaluating the extent of the wildfires. Our new calculations show that the fires were not ignited in a single pulse, but in multiple pulses at different times around the world," Kring said.

Planetary scientist Frank Kyte of the University of California, Los Angeles, said the wildfire models make sense.

"It all sounds reasonable. I certainly believe that there were wildfires. I'm revising a paper now that reports significant amounts of soot in KT sediments [which mark the geologic boundary between the Cretaceous and Tertiary Periods] from the central north Pacific, so fires must have been very widespread."