Supernova Killed Off Ancient Megalodon Shark, Study Says

Posted: Dec 15 2018, 1:20pm CST | by , Updated: Dec 15 2018, 1:27pm CST, in Latest Science News

 

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Supernova Killed off Ancient Megalodon Shark, Study Says
Credit: j.palaeo

New study suggests that supernova energy caused cancers and mutations especially to larger animals in coastal waters.

A supernova that exploded about 2.6 million years ago has likely shaped the world we live in. The particular supernova is thought to have occurred some 150 light years away from Earth. It caused catastrophic disturbances to our planet’s climate and triggered widespread extinction of marine life including a bus-sized shark called Megalodon.

Megalodon shark lived approximately 2.6 million years ago and grew to over 50 feet long. But why the massive shark suddenly disappeared remains a mystery.

Given the incredible amounts of energy in a supernova explosion, researchers suggest that any such event in nearby space can wreak havoc on life of Earth. In the latest effort, they have investigated cosmic energy from the supernova as it propagated through our atmosphere to the surface to understand its effect on living organisms.

“I've been doing research like this for about 15 years, and always in the past it's been based on what we know generally about the universe – that these supernovae should have affected Earth at some time or another," said lead author Adrian Melott from University of Kansas. "This time, it's different. We have evidence of nearby events at a specific time. We know about how far away they were, so we can actually compute how that would have affected the Earth and compare it to what we know about what happened at that time – it's much more specific.”

When researchers look at ancient seabed deposits of the Pliocene–Pleistocene boundary, they find a dramatic rise in iron-60, which is a radioactive isotope produced during a supernova. Evidence suggest that a series of supernova explosions has spread layers of iron-60 all over the world 2.5 million years ago.

"We have the Local Bubble in the interstellar medium. The best way to manufacture a bubble like that is a whole bunch of supernovae blows it bigger and bigger, and that seems to fit well with idea of a chain,” said Melott. “When we do calculations, they're based on the idea that one supernova that goes off, and its energy sweeps by Earth, and it's over. But with the Local Bubble, the cosmic rays kind of bounce off the sides, and the cosmic-ray bath would last 10,000 to 100,000 years. This way, you could imagine a whole series of these things feeding more and more cosmic rays into the Local Bubble and giving us cosmic rays for millions of years."

The nearby supernova that released iron-60 isotopes also caused particles called muons to shower Earth and triggered mutations especially in larger animals. According to the study, larger organisms in coastal waters received a greater radiation dose from the muons and the elevated radiation wiped out around 36 percent of the genera in the world.

"One of the extinctions that happened 2.6 million years ago was Megalodon. Imagine the Great White Shark in 'Jaws,' which was enormous—and that's Megalodon, but it was about the size of a school bus. They just disappeared about that time. So, we can speculate it might have something to do with the muons. Basically, the bigger the creature is the bigger the increase in radiation would have been,” said Melott.

“We know something happened and when it happened, so for the first time we can really dig in and look for things in a definite way. We now can get really definite about what the effects of radiation would be in a way that wasn't possible before."

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.

 

 

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