For decades, the story of the dinosaurs’ demise has centered on a single event: an asteroid smashing into the Earth, creating the Chicxulub crater off the coast of Mexico. The massive impact unleashed chaos across the planet, sparking wildfires, blocking sunlight, and ultimately wiping out 75% of Earth’s species, including nearly all of the dinosaurs.

But it turns out, Chicxulub may not have acted alone.

The Nadir Crater

Buried beneath the Atlantic Ocean, deep off the coast of West Africa, lies the remains of another catastrophic event — a 9-kilometer-wide crater left behind by a second asteroid impact. This crater, named the Nadir Crater, has only recently been fully revealed thanks to high-tech imaging that peels back the layers of Earth’s seabed.

Dr. Uisdean Nicholson of Heriot-Watt University in Scotland first discovered hints of the Nadir Crater in 2022. But it wasn’t until now, with the help of detailed 3D seismic data, that the full extent of this ancient scar on the planet has come to light. And what it tells us is astonishing: around the same time that Chicxulub smashed into what is now Mexico’s coast, another asteroid, about 450 meters wide, hurtled into Earth at a blistering 72,000 kilometers per hour.

The asteroid’s impact would have sent shockwaves across the ocean, shaking the seabed violently. The seabed was liquefied, landslides tumbled, and towering tsunami waves — at least 800 meters high — raced across the Atlantic.

The discovery of the Nadir Crater comes as a huge surprise for everyone. For decades, Chicxulub has been the singular focus, the main culprit in the extinction that ended the Cretaceous period. But Nadir suggests an even more gruesome story: a terrifying double-strike that sealed the fate of dinosaurs and countless other lineages for good.

Could it be that Earth was hit by a barrage of asteroids around the same time? Was Nadir a fragment of the Chicxulub asteroid, breaking off in space before smashing into Earth? Or was this just an eerie coincidence, two separate asteroids colliding with Earth in the worst cosmic bad luck imaginable?

The Smoking Gun

In 3D seismic images shared by TGS, a global geophysical company, researchers have been able to peer inside the Nadir Crater with an unprecedented level of detail. It’s a rare opportunity. While most craters on Earth have been eroded away by time, and craters on the moon only show surface features, Nadir has remained remarkably well-preserved under layers of sediment.

“There are around 20 confirmed marine craters worldwide, and none of them has been captured in anything close to this level of detail. It’s exquisite,” Nicholson said.

“We’ve gone from a fuzzy blob to a crystal-clear image of the crater,” he added. “It’s like going from a grainy ultrasound to a full 3D scan.”

With such good data, scientists have been able to reconstruct the aftermath of the impact, down to the minute. After the asteroid struck, a bowl-shaped crater formed instantly. This was followed by a central peak that pushed up from the seabed as if the Earth itself was rebounding. Seismic waves rippled through the surrounding rock, triggering landslides and liquefying the seabed across a vast area. Tsunamis surged outward, their power rippling across the ocean before rebounding back toward the crater in a chaotic, resurgent flood.

But, as terrifying as this may sound, Nadir paled in comparison to Chicxulub’s destruction. The latter was nearly 10,000 meters wide, compared with Nadir’s 450 meters. However, the energy unleashed by Chicxulub would have been thousands of times greater than its smaller armageddon companion.

Could It Happen Again?

The prospect of something like this happening again in the near future is extremely unlikely, but the dangers shouldn’t be ignored. Another asteroid, Bennu, which measures around 400 meters in diameter, is currently considered one of the most dangerous near-Earth objects in the solar system. Its odds of hitting Earth are slim — NASA estimates a 1 in 2,700 chance of impact in 2182 — but Bennu is still large enough to make us pay attention.

Fortunately, NASA’s planetary defense program is becoming increasingly sophisticated. In 2022, NASA slammed the DART spacecraft into Dimorphos, a potato-shaped moonlet orbiting the larger asteroid Didymos, millions of miles away from Earth. This asteroid was no threat to us, but proved to be a good training target. The kinetic impact was powerful enough to sway Didymos off course, showing that we wouldn’t be entirely helpless were an asteroid to threaten Earth. However, this method requires years of advance warning. More recently, scientists have proposed using X-rays from nuclear blasts as a last-ditch effort to eliminate an asteroid threat.

For now, the Nadir Crater adds to our understanding of the dangers Earth faced during the end of the Cretaceous period. Researchers are hoping to drill into the crater’s seabed and extract cores to better understand the immense pressures involved during the impact and to pinpoint the exact timing of the event.

Dr. Sean Gulick, a geophysicist at the University of Texas at Austin, said the Nadir Crater provides a unique opportunity. “It allow us to consider how impact processes and craters scale with the size of the impactor both for understanding the evolution of the Earth and other worlds,” he noted.

For Dr. Nicholson and his team, the work is just beginning

The findings appeared in the journal Communications Earth & Environment.