The huge asteroid that hit Earth and wiped out the dinosaurs 66 million years ago was not alone, scientists have confirmed.
A second, smaller space rock smashed into the sea off the coast of West Africa creating a large crater during the same era. It would have been a “catastrophic event”, the scientists say, causing a tsunami at least 800m high to tear across the Atlantic ocean.
Dr Uisdean Nicholson from Heriot-Watt University first found the Nadir crater in 2022, but a cloud of uncertainty hung over how it was really formed. Now Dr Nicholson and his colleagues are sure that the 9km depression was caused by an asteroid hurtling into the seabed.
They cannot date the event exactly, or say whether it came before or after the asteroid which left the 180km-wide Chicxulub crater in Mexico. That one ended the reign of the dinosaurs.
But they say the smaller rock also came at the end of the Cretaceous period when they went extinct. As it crashed into Earth's atmosphere, it would have formed a fireball.
The asteroid that created the Nadir crater measured around 450-500m wide, and scientists think it hit Earth at about 72,000km/h.
The findings are reported in Nature Communications Earth & Environment.
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