The event had to be something truly extraordinary. It had to be so devastating that all the large vertebrates on land, at sea, and in the air died at once.
What killed the dinosaurs? It’s a debate that has been raging in for decades, if not centuries. Many believe that 66 million years ago a giant, six-mile wide asteroid crash-landed on Earth and completely wiped out many of the creatures living at that time. However, new research suggests that the asteroid was just the start.
A recent paper published in the journal Science submits that the asteroid set off a chain reaction of cataclysmic events, the sum of which drove the dinosaurs to extinction.
Around 66 million years ago, at the close of the Cretaceous period, many living species disappeared at once. This moment is called the Cretaceous-Tertiary boundary, or K-T boundary.
“It’s one of the great mysteries of the history of the planet,” said study lead author and geologist Paul Renne. “How do you just wipe out such a large, diverse, and dominant kind of animal forever in the blink of an eye? It is an amazing thing.”
Prior to this paper, there were two main theories about the disappearance. The first is that a giant asteroid or comet struck the Earth in the Gulf of Mexico. The second theory argues that an influx of volcanic activity, occurring around the same time frame, produced massive lava flows that wiped out multiple life forms.
9,000 miles away from Chicxulub, the impact crater in Mexico, one can find the Deccan Traps in India, one of the largest volcanic formations to be found on Earth.
The new paper dates both of these geological features more precisely than ever before. The events must have occurred relatively soon after one another.
“An impact the size of the one that happened at the K-T boundary, according to what we know, probably happens only once every billion years or so on Earth. It’s really improbable,” said Renne. “The notion that it should coincide with an outburst of volcanism – which is certainly not as rare, but also relatively infrequent – by chance, is really, really small.”
“When you’re dealing with coincidences that are highly improbable, you have to think about the idea that there may be a relationship between them.”
The event that occurred at the K-T boundary had to be something truly extraordinary. It had to be so devastating that all the large vertebrates on land, at sea, and in the air died at once.
“Major transitions in life on our planet are probably not caused by really simple events. They’re really complicated events. It’s all of these different phenomena acting together with all their feedback,” said Renne.
The impact from the asteroid theoretically produced huge shock waves that reverberated around the planet. Earthquakes frequently cause volcanic activity. The disturbance as great as the asteroid strike caused underground chambers of magma to become wildly unstable, leading to extraordinary volcanic activity.
“If you just extrapolate the scale of volcanism and the scale of the seismic energy, it looks like that would work,” said Renne.
If an asteroid six miles wide really struck the Earth, it would have produced an earthquake that would register as a magnitude 11 on the Richter scale. The destructive earthquake that struck Chile last year was a magnitude of 8.2.
A earthquake that violent would have shock the Earth to its very core, creating a tidal wave of molten lava that rose from the core, through the mantle, and finally, out through already active volcanoes- such as the Deccan Traps in India.
The volcanoes would have released massive amounts of lava flows. In India, the Deccan Traps spewed enough lava to cover an area the size of Utah and Nevada with a mile-thick layer of volcanic rock.
In addition, colossal ash and gas clouds would have been shot into the air. Much like the clouds that blanketed Pompeii, this ash cloud would have buried numerous beings alive.
The gases released in the air would have been carbon dioxide and methane- greenhouse gases. The amount of gas released into the atmosphere raised the global temperature by several degrees.
This combined catastrophe would force anything living on earth to adapt or perish.
“If our high-precision dates continue to pin these three events – the impact, the extinction and the major pulse of volcanism – closer and closer together, people are going to have to accept the likelihood of a connection among them. The scenario we are suggesting – that the impact triggered the volcanism – does in fact reconcile what had previously appeared to be an unimaginable coincidence,” said co-author Mark Richards of UC Berkeley.
“Is this going to lay to rest the long-standing controversy about what happened? I don’t think it will,” said Renne. He hopes, however, that future research will challenge or support or even augment his claims.
The extinction of the dinosaurs will still capture the imaginations of generations to come.
“Prior to the extinction, mammals were just tiny little rat-like things that wandered around and tried to avoid getting crushed or eaten,” said Renne. “When the dinosaurs went away, opportunities in the ecosystem were opened up and mammals took off.”
“One could say, we are mammals and we would not exist – that humans would not have evolved had it not been for the dinosaurs’ disappearance.”
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