About 66 million years ago, an asteroid impact wiped out three-quarters of all plant and animal species on Earth, most notably causing the extinction of the dinosaurs. Exactly how the impact triggered those extinctions, however, has been the subject of intense debate.

According to a new study published in the Journal of Geophysical Research: Biogeosciences, the collision may have generated an enormous dust cloud that superheated the upper atmosphere, scorching living organisms unable to find shelter and igniting widespread fires.

The most widely accepted explanation for the catastrophic mass extinction is known as the Alvarez hypothesis, named after the late physicist Luis Alvarez and his son Walter, a geologist. In 1980, they proposed that the extinction event may have been caused by a massive asteroid or comet striking Earth.

They based their conclusion on analyses of sediment layers around the world dating to the Cretaceous-Paleogene boundary, or K-Pg boundary, formerly known as the K-T boundary. These layers contained unusually high concentrations of iridium, a metal more common in asteroids than on Earth. That same year, Dutch geophysicist Jan Smit independently reached a similar conclusion.

Scientists have since identified the likely impact site: the vast Chicxulub crater on Mexico’s Yucatán Peninsula, first discovered by geophysicists in the late 1970s. The object that created it was large enough—between 11 and 81 kilometers, or 7 and 50 miles, across—to melt, fracture and eject granite from deep within the Earth. It probably also caused a megatsunami and hurled vaporized rock and sulfates into the atmosphere.

The impact is estimated to have released more than a billion times the energy of the atomic bombs dropped on Hiroshima and Nagasaki in 1945. As one researcher put it, the conditions may have been severe enough to kill virtually every exposed form of life within the first hour or two.