It may not have been just one asteroid that wiped out the dinosaurs but two, a new breakthrough discovery suggests.
An Edinburgh scientist has identified a six mile-wide crater just off the coast of West Africa thought to have been created by a vast rock which hit the Earth around 66 million years ago.
The crater is thought to have been created at a similar time as the crater in the Gulf of Mexico caused by a larger eight mile-wide asteroid that smashed into the Earth and caused horrific conditions that killed off the dinosaurs.
The new crater, nicknamed Nadir, appears to have been caused by a 400-metre wide asteroid that would have caused a huge tsunami.
Dr Uisdean Nicholson, of Heriot-Watt University in Edinburgh, spotted the crater feature in surveys used by the oil and gas industry.
“It definitely fits the bill for an impact crater,” he said.
“These surveys are kind of like an ultrasound of Earth. I’ve spent probably the last 20 years interpreting them, but I’ve never seen anything like this.
“Nadir’s shape is diagnostic of an asteroid impact. It’s got a raised rim surrounding a central uplift area, and then layers of debris that extend outwards.”
Nadir sits more than 300 metres below the seabed some 250 miles off the coast of Guinea.
Dr Nicholson had been analysing seismic survey data frequently obtained by oil and gas prospectors.
They record the different layers of rock and sediment underground often to a depth of several kilometres.
It has triggered speculation that the asteroid that caused it may have broken off from the larger asteroid known to have caused hellish conditions on Earth leading to mass extinctions.
Dr Nicholson suggests that gravity could have broken the asteroid apart during an earlier orbit that passed closer to Earth, leading to two impacts within a few days of each other.
Dr Veronica Bray, of the University of Arizona, said: “Our simulations suggest this crater was caused by the collision of a 400m-wide asteroid in 500-800m of water.
“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.”
The crater in the Gulf of Mexico, called Chicxulub, is estimated to have been caused by a collision 10 million times greater.
However some experts are not convinced both rocks came from the same parent asteroid.
Prof Gareth Collins at Imperial College London, told the New Scientist: “This is an exciting discovery.
“It certainly has lots of features consistent with an impact origin.”
But he added: “I think that the two events are more likely to be unrelated,”
The discovery is reported in the journal Science Advances.