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2 months ago
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It's well known that the reign of the dinosaurs came to an end when a giant asteroid smashed into Earth 66 million years ago.
But a new study suggests that this huge asteroid wasn't alone.
Scientists from Heriot Watt University have discovered evidence that a second devastating space rock smashed into Earth in the same year.
This second asteroid measured around 1,640ft (500 metres) wide, and struck Earth just off the coast of the Republic of Guinea in West Africa.
'The closest humans have come to seeing something like this is the 1908 Tunguska event, when a 50-metre asteroid entered Earth's atmosphere and exploded in the skies above Siberia,' said Dr Uisdean Nicholson, who led the study.
It's well known that the reign of the dinosaurs came to an end when a giant asteroid smashed into Earth 66 million years ago. But a new study suggests that this huge asteroid wasn't alone (stock image)
The first evidence of this second asteroid was uncovered in 2022, while Dr Nicholson and his team were studying seismic reflection data of the Atlantic Ocean's seabed.
The data revealed a depression measuring almost five miles (9km) deep, which the team suspected could be an asteroid impact crater.
Now, the researchers have taken new high-resolution, 3D seismic images of the depression, which have confirmed their suspicions.
The crater has been dubbed the Nadir Crater, and was carved out when an asteroid struck Earth around 66 million years ago – the same age as the dinosaur-killing asteroid.
'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,' Dr Nicholson said.
Now, the researchers have taken new high-resolution, 3D seismic images of the depression, which have confirmed their suspicions
Scientists from Heriot Watt University have discovered evidence that a second devastating space rock smashed into Earth in the same year as the one that wiped out the dinosaurs
'Craters on the surface are usually heavily eroded and we can only see what is exposed, whereas craters on other planetary bodies usually only show the surface expression.
'These data allow us to image this fully in three dimensions and peel back the layers of sedimentary rock to look at the crater at all levels.'
Back in 2022, the researchers suggested that the asteroid would have been around 400 metres wide.
However, the new images confirm that it was even bigger than this.
Dr Nicholson said: 'We now think it was 450-500m wide, because of the larger crater size as shown by the 3D data.
'We can tell it came from about 20-40 degrees to the northeast, because of spiralling thrust-generated ridges surrounding the crater's central peak - those are only formed following a low-angle oblique impact.
'And we think it would have hit Earth at about 20 km per second, or 72,000 km per hour, although we still need to confirm this with a new set of impact models.'
This second asteroid measured around 1,640ft (500 metres) wide, and struck Earth just off the coast of the Republic of Guinea in West Africa (Nadir Crater, pictured)
Based on the data, the scientists have created a timeline of what they think happened – from the initial collision to an 800-metre-plus high tsunami that would have travelled across the Atlantic ocean.
'After the impact and the central uplift forming, the soft sediments surrounding the crater flowed inwards towards the evacuated crater floor, creating a visible "brim",' Dr Nicholson explained.
'The earthquake shaking caused by the impact appears to have liquefied the sediments below the seabed across the entire plateau, causing faults to form below the seabed.
'The impact was also associated with large landslides as the plateau margin collapsed below the ocean.
'As well as this, we see evidence for a train of tsunami waves going away from, then back towards the crater, with large resurge scars preserving evidence of this catastrophic event.'
While it's been 116 years since an asteroid like this has been seen, it likely won't be long before another huge space rock strikes our planet, according to NASA.
The US space agency predicts that asteroid Bennu has a one in 2,700 chance of smashing into Earth on 24 September 2182.
HOW THE DINOSAURS BECAME EXTINCT AROUND 66MILLION YEARS AGO
Dinosaurs ruled the Earth around 66million years ago, but suddenly disappeared in what is known as the Cretaceous-Tertiary extinction.
It was believed for many years that the changing climate destroyed the food chain of the huge reptiles.
However, in the 1980s paleontologists discovered a layer of iridium - an element that is rare on Earth but found in vast quantities in space.
When this was dated, it coincided precisely with when the dinosaurs disappeared from the fossil record.
A decade later, scientists uncovered the massive Chicxulub Crater at the tip of Mexico’s Yucatán Peninsula, which dates to the period in question.
Scientific consensus now says that these two factors are linked and they were both probably caused by an enormous asteroid crashing to Earth.
With the projected size and impact velocity, the collision would have caused an enormous shock wave and is likely to have triggered seismic activity.
The fallout would have created plumes of ash thought to have covered the whole planet, making it impossible for dinosaurs to survive.
Other animals and plant species had a shorter time-span between generations which allowed them to survive.
There are several other theories as to what caused the demise of the dinos.
One early theory was that small mammals ate dinosaur eggs and another proposes that toxic angiosperms (flowering plants) killed them off.
