Impact Crater May Be Dinosaur Killer's Baby Cousin

Researchers have discovered a second impact crater on the other side of the Atlantic that could have finished off what was left of the dinosaurs, after an asteroid known as Chicxulub slammed into what is now the Gulf of Mexico 66 million years ago. The BBC reports: Dubbed Nadir Crater, the new feature sits more than 300m below the seabed, some 400km off the coast of Guinea, west Africa. With a diameter of 8.5km, it's likely the asteroid that created it was a little under half a kilometre across. The hidden depression was identified by Dr Uisdean Nicholson from Heriot-Watt University, Edinburgh, UK. [...] "Our simulations suggest this crater was caused by the collision of a 400m-wide asteroid in 500-800m of water," explained Dr Veronica Bray from the University of Arizona, US. "This would have generated a tsunami over one kilometre high, as well as an earthquake of Magnitude 6.5 or so. "The energy released would have been around 1,000 times greater than that from the January 2022 eruption and tsunami in Tonga." Dr Nicholson's team has to be cautious about tying the two impacts together. Nadir has been given a very similar date to Chicxulub based on an analysis of fossils of known age that were drilled from a nearby borehole. But to make a definitive statement, rocks in the crater itself would need to be pulled up and examined. This would also confirm Nadir is indeed an asteroid impact structure and not some other, unrelated feature caused by, for example, ancient volcanism. [...] Prof Sean Gulick, who co-led the recent project to drill into the Chicxulub Crater, said Nadir might have fallen to Earth on the same day. Or it might have struck the planet a million or two years either side of the Mexican cataclysm. Scientists will only know for sure when rocks from the west African crater are inspected in the lab. "A much smaller cousin, or sister, doesn't necessarily add to what we know about the dinosaurs' extinction, but it does add to our understanding of the astronomical event that was Chicxulub," the University of Texas at Austin researcher told BBC News.

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