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dinosaur extinction head

Sixty-six million years agone, an asteroid roughly 9 kilometers in diameter slammed into the Gulf of Mexico virtually the Yucatán Peninsula. The massive bear on created the Chicxulub crater (named for a nearby town) and wiped out the dinosaurs. It's one of the most-studied mass extinction events. A new analysis of the impact suggests that we, by which I mean mammals and other modern species, were extremely lucky. If the impact had happened a few minutes later, we might never take existed at all.

Here's why: In 1980, a team led by Luis Alvarez discovered evidence of a thin layer of iridium deposited across the Earth. That was a noteworthy discovery because iridium is comparatively rare on the planet's surface–finding a thin layer of it distributed across huge amounts of the planet at a specific moment in geologic fourth dimension suggested a massive impact past an asteroid comparatively rich in iridium. This boundary layer is referred to as the K-T or K-Pg boundary.

But that's not all we've found. There'due south a layer of soot distributed across the world as well. One of the coolest things about the K-PG purlieus is that you can actually see information technology in diverse rock formations with no prior geological training:

Cretaceous_Paleogene_clay_at_Geulhemmergroeve

Image courtesy of Wikipedia

A recent paper by Kunio Kaiho and Naga Oshima investigated why the K-Pg touch on was and so destructive and came to a startling conclusion: If the impact had happened just a few minutes afterwards, it might not have kicked off a mass extinction at all. According to their written report, the Chicxulub bear upon happened in an surface area of the Earth that was unusually rich in hydrocarbons and decayed organic matter, as shown below:

ImpactEvent

The Chicxulub impact smashed into one of the few spots on Earth where at that place were huge concentrations of hydrocarbons laid downwards past the decay of animals and plants over millions of years. Just 13 percent of the planet held those deposits at the time. A huge volume of soot from the burned material was ejected into the air, leading to a catastrophic drib in global temperatures, possibly aided past loftier levels of sulfur.

While Kaiho and Oshima fence that this global layer of soot drove the mass extinction issue, other scientists aren't and so certain. "The xiii percent number they're quoting has a lot of assumptions based around it," Sean Gulick, a geophysicist at the University of Texas at Austin, told the Washington Post. The asteroid churned upwards soot, he said, simply soot was "not the driver" that killed the dinosaurs.

In truth, there are multiple potential drivers that could have collectively contributed to the event. The asteroid struck a relatively shallow trunk of h2o, increasing the amount of ejected material flung back into the atmosphere. The impact upshot could have fed the ongoing eruption of the Deccan Traps, a massive volcanic germination in India that may take played a office in multiple extinction events. If the Chicxulub impact event had occurred over the deepest part of the Pacific, the asteroid would take had to vaporize vii miles of water before hitting the bottom of the body of water. While that'due south still a tremendous impact, it would have bled off a not-little amount of the asteroid's bear upon energy and limited the amount of textile released into the atmosphere.

In curt, this is an interesting argument for the uniqueness of the Chicxulub impact and the evolution of mammals leading to the existence of our ain species. But it'll be difficult to ever come up with a single unified explanation that admittedly answers our questions almost what led to the extinction of the dinosaurs and our own existence.