Sixty-six million years ago, an enormous asteroid hurtled into Earth, creating an explosion with the force of about 100 trillion tons of TNT. Soot from the ensuing fires, dust and greenhouse gasses spewed into the atmosphere, blocking out the sun and leading to a widespread ecosystem collapse. Some 75 percent of the planet’s species died off, including all non-avian dinosaurs.
But had circumstances been different, the impact may not have been quite so devastating. As Mary Beth Griggs reports for Popular Science, a new study suggests that the asteroid hit just the right spot—or the wrong one, if you were a dinosaur—to cause a mass extinction.
The study, published in Scientific Reports, proposes that the asteroid strike was particularly catastrophic because it occurred in an area—now located on the Yucatán Peninsula in Mexico—that was rich in hydrocarbons. Blistering temperatures at the site of the impact ignited these materials, sending massive quantities of soot and into the air.
As Nicholas St. Fleur of the New York Times reports, researchers used modern-day measurements of sedimentary rock and organic compounds to create a model of the distribution of hydrocarbons 66 million years ago. And they found that just 13 percent of the Earth’s surface contained enough hydrocarbons to obscure the sun and trigger the global cooling event that caused dinosaurs to die out.
In other words, had the asteroid landed in almost any other location on the planet, dinosaurs “could still be alive today,” Kunio Kaiho, a paleontologist at Tohoku University in Japan and lead author of the study, tells St. Fleur.
But some experts have cast doubt on the study’s findings. Sean P.S. Gulick, a marine geophysicist at the University of Texas at Austin, tells St. Fleur that he agrees “location, location, location” was important in determining the outcome of the asteroid strike. But his research has shown that only small amounts of hydrocarbons would have been present at the impact site 66 million years ago. Instead, Gulick believes that soot released by firestorms that raged after the crash—and not burning fossil fuels—led to the mass extinction.
Additionally, as Ian Sample of the Guardian points out, the asteroid may have only been part of the dinosaurs’ problem. Previous research has suggested that the prehistoric creatures were already weakened by a loss of biodiversity when the space rock hit, and may have survived the strike had it occurred at a time when they were more robust.
But whether it was the timing or the location of the asteroid strike that did them in, the dinosaurs seem to have been rather unlucky. But had they not had this streak of bad luck, the world would have looked very different than the one we know today. Dinosaurs’ extinction cleared the way for the ascendance of mammals—including, eventually, humans.