Two Asteroids, One Dinosaur Extinction: Second Crater Bolsters Double Impact Theory

Sharp, three-dimensional seismic information of a seafloor crater disconnected Guinea seems to corroborate that a 2nd asteroid deed Earth astatine astir the aforesaid clip arsenic the behemoth that deed North America 66 cardinal years ago, ending the reign of the dinosaurs.

A squad of researchers precocious imaged the 5.28-mile-wide (8.5-kilometer-wide) slump disconnected the African coast, giving the squad a overmuch amended characterization of the crater’s features. Based connected its analysis, the squad confirmed the crater’s property and ruminated connected the contiguous aftermath of the impact.

The dinosaurs—besides the ancestors of modern birds, of course—went extinct 66 cardinal years ago, aft a monolithic asteroid slammed into what is present Mexico’s Yucatán Peninsula astatine the “deadliest imaginable angle,” according to a 2020 paper. Research published successful 2021 indicated the asteroid astir apt deed successful springtime, but the effect would’ve been catastrophic successful immoderate weather: 100 cardinal megatons of force threw Earth’s systems retired of whack.

Part of the trouble that dinosaurs and astir different walks of past beingness faced was that the asteroid kicked up tsunami waves champion measured successful miles, arsenic good arsenic dust, soot, sulfur, and much dust that caused the extinction of astir 75% of life. In different words, it wasn’t conscionable the cataclysmic interaction of a elephantine stone from space—it was besides the aftermath caused by that impact.

But the Chicxulub asteroid evidently didn’t enactment alone. In 2022, a squad including respective members of the caller squad revealed the bowl-shaped feature and dubbed it the Nadir Crater. The crater is buried nether astir 1,300 feet (400 meters) of sediment connected the Guinea Plateau, a swath of continental crust that juts retired astir 250 miles (400 km) from the coasts of Guinea and Guinea Bissau.

In the caller paper, the probe squad published images of the asteroid interaction crater, confirmed its property astatine 66 cardinal years old, and projected what happened successful the contiguous aftermath of the impact. The team’s probe was published contiguous successful Communications Earth & Environment.

In its 2022 paper, the squad suggested 3 imaginable origins of the crater. One possibility, the researchers said, is that a ample asteroid broke disconnected from the aforesaid genitor assemblage arsenic the Chicxulub asteroid successful the Yucatán arsenic it approached Earth. Another enactment is that immoderate collision successful the asteroid loop sent a barrage of asteroids towards Earth successful the same, astir million-year timeframe. A last enactment is that the timing of the 2 impacts was axenic coincidence: that 2 elephantine abstraction rocks deed Earth astatine astir the aforesaid time, successful what was conscionable other rotten luck for the dinosaurs.

“The asteroid liable for Chicxulub is acold bigger than that which we suggest for Nadir,” Uisdean Nicholson, a geoscientist astatine Heriot-Watt University successful Scotland and pb writer of some papers, told Gizmodo successful 2022. “We would expect astir 10,000 times much vigor to beryllium released from Chicxulub. So the Nadir interaction would person been dwarfed by Chicxulub.”

Just past month, a antithetic squad of researchers published enactment successful Science positing that the genitor assemblage of the Chicxulub and Nadir asteroids came from good beyond Jupiter, lending credence to the asteroid-belt root hypothesis.

The squad estimated that the Nadir asteroid deed the Earth traveling astatine astir 12.43 miles per 2nd (20 kilometers per second), oregon astir 45,000 miles per hr (72,000 km/hr). In a Heriot-Watt University release, Nicholson said that earthquakes caused by the interaction “liquified the sediments beneath the seabed crossed the full plateau” and caused ample underwater landslides. Based connected the crisp images of the crater, the squad besides projects that the interaction caused a half-mile-high (800 meters) tsunami, if not taller.

66 cardinal years agone was already known to beryllium a beauteous crappy clip to beryllium a surviving happening connected Earth. But confirmation of the Nadir Crater’s property doubles down connected that idea. The squad has applied to drill into the seabed to retrieve sediment cores from the crater itself, which volition further clarify the unit with which the past asteroid deed the seafloor and however the contiguous aftermath of the lawsuit whitethorn person unfolded.