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from the supernovae-have-that-effect-on-planets dept.
Researchers consider whether supernovae killed off large ocean animals at dawn of Pleistocene
About 2.6 million years ago, an oddly bright light arrived in the prehistoric sky and lingered there for weeks or months. It was a supernova some 150 light years away from Earth. Within a few hundred years, long after the strange light in the sky had dwindled, a tsunami of cosmic energy from that same shattering star explosion could have reached our planet and pummeled the atmosphere, touching off climate change and triggering mass extinctions of large ocean animals, including a shark species that was the size of a school bus.
[...] The effects of such a supernova — and possibly more than one — on large ocean life are detailed in a paper just published in Astrobiology.
[...] A supernova 2.6 million years ago may be related to a marine megafaunal extinction at the Pliocene-Pleistocene boundary where 36 percent of the genera were estimated to become extinct. The extinction was concentrated in coastal waters, where larger organisms would catch a greater radiation dose from the muons.
According to the authors of the new paper, damage from muons would extend down hundreds of yards into ocean waters, becoming less severe at greater depths: "High energy muons can reach deeper in the oceans being the more relevant agent of biological damage as depth increases," they write.
Indeed, a famously large and fierce marine animal inhabiting shallower waters may have been doomed by the supernova radiation.
"One of the extinctions that happened 2.6 million years ago was Megalodon," Melott said. "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."
Megalodon (Carcharocles megalodon).
Hypothesis: Muon Radiation Dose and Marine Megafaunal Extinction at the End-Pliocene Supernova (DOI: 10.1089/ast.2018.1902) (DX)
(Score: 1, Interesting) by Anonymous Coward on Friday December 14 2018, @08:36AM (7 children)
There were no megs on the other side of the planet? Or did the radiation bath last more than a day?
What would humans do? How do you teach your grandchildren to prepare for something (tunnels underground) that will happen long after you are dead?
(Score: 2) by MostCynical on Friday December 14 2018, @09:20AM (3 children)
well, it was an ice age [livescience.com], so there may have been more shallow water, but it seems C. Mastodon got around [prehistoric-wildlife.com], so maybe months of exposure was enough to knock it off.
It did manage to survive for over 25 million years, so it will have 24,990,000 over us.
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 0) by Anonymous Coward on Friday December 14 2018, @10:24AM
Could be a cascading extinction event? Radiation kills off tons of plankton, starvation kills plankton eaters, etc. until megalodon is left without enough food species to survive? I would think that larger species are probably have lower population densities, as well as higher sensitivity to fluctuations in food supply, so a significant event further down the food chain could have a magnified effect?
(Score: 0) by Anonymous Coward on Friday December 14 2018, @10:43AM (1 child)
Mastodon was a mammal similar to Mammoth, Megalodon was a giant shark.
(Score: 2) by MostCynical on Friday December 14 2018, @11:11AM
I meant one, typed the other. Links are for the correct beast.
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 0) by Anonymous Coward on Friday December 14 2018, @11:32AM
Judging from how humans deal with other global threats, I think many will just deny the danger, and those who don't will form committees, but not do anything substantial about it.
(Score: 0) by Anonymous Coward on Friday December 14 2018, @12:09PM
"There were no megs on the other side of the planet? Or did the radiation bath last more than a day?"
How small and fleeting do you think a freaking supernova is going to be?
(Score: 3, Informative) by ewk on Friday December 14 2018, @01:11PM
"did the radiation bath last more than a day"
Yes.
Since your run-of-the-mill supernova seems to last a few months (https://www.universetoday.com/119733/how-quickly-does-a-supernova-happen/ gives "... supernova will then take a few months to reach its brightest point...") I'd say it's save to assume the radiation bath lasts more than a day.
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