The asteroid that vaporized the dinosaurs may now be synonymous with mass annihilation, but it almost wasn’t.
If that same monster asteroid had crashed somewhere else (and almost anywhere else) on the planet on that doomsday 66 million years ago, giant lizards might have survived to stomp cities like Godzilla. It was the chemical makeup of its kill zone that sentenced so many species to extinction, which is why Japanese scientists Kunio Kaiho and Naga Oshima determined that the space rock pummeled Earth in just about the worst possible area.
“This significant event could [only] have occurred if the asteroid hit the hydrocarbon-rich areas occupying approximately 13% of the Earth’s surface,” they said in a study recently published in the journal Nature.
Nothing is going to look the same anytime soon after an asteroid impact, but it wasn’t the size of the rock nor the speed at which it zoomed through the atmosphere and toward the Yucatan Peninsula that decided the dinosaurs’ future. The chemical makeup of the land it hit at what is now Chicxulub crater was really what would end up obliterating them. Hydrocarbons and sulfur in the rocks it smashed were released into the air as sulfate aerosols and thick clouds of soot into the stratosphere, which brought on a severe drought and made global temperatures plummet. Think 300 gigatons of sulfur and 429 gigatons of carbon dioxide. This is one phenomenon even colossal reptiles couldn’t live through.
Some argue that dinosaurs were already on the decline and would have been eventually snuffed out even if there had been no catastrophe. Mammals were emerging, eager to compete with the lizards when it came to snatching up plant life and make a meal out of unguarded dinosaur eggs. Opponents of this theory argue that while some species of dinosaurs were disappearing, others were thriving. The dino-destroying asteroid had defied odds more enormous than its victims. Anything alive during the end of the Cretaceous era would have still been crawling around today had it hit a target on the 87% of Earth that doesn’t have high levels of hydrocarbons.
“The probability of mass extinction was quite low even with an asteroid as large as the [Chicxulub asteroid], because hydrocarbon-rich and sulfate-rich sites were rare,” said Kaiho and Oshima. If the asteroid had hit a low–medium hydrocarbon area, mass extinction could not have occurred.”
Had the impact happened somewhere with low to medium hydrocarbon saturation, temperatures on Earth would have not cooled the 8 to 11 degrees necessary for a mass extinction event.
While it may have been sort of awesome to encounter a dinosaur in the flesh, you probably wouldn’t think so if your head ended up in its jaws. They're safer as fossils.