Cosmic energy from the collapsing star may have been responsible for the mass extinction that occurred on Earth during the Pliocene era some 2.6 million years ago, according to a new study published in the journal Astrobiology.
The massive amounts of radiation, which is believed to have travelled 150 light years, pummeled the Earth’s atmosphere, touching off climate change and triggering mass extinctions. Among the species that died off during the Pliocene-Pleistocene boundary event was the megalodon shark.
“They just disappeared about that time,”said lead author Adrian Melott, professor emeritus of physics & astronomy at the University of Kansas. “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.”
Muons are heavy electrons caused by supernovae that can cause cancers and mutations in animals—especially to larger species. Ancient seabed deposits of iron-60 isotopes provided the evidence of the timing and distance of supernovae that could have accounted for a surge in these muons.
The timing coincides with the mass extinction in which over 1/3 of all species on the planet disappeared. The extinctions were concentrated in coastal waters, where larger organisms would catch a greater radiation dose from the muons.
Little is known about the megalodon other than it was one of the largest marine predators on the planet, reaching lengths of over 60 feet. It first appeared in the fossil record nearly 20 million years ago but mysteriously disappeared completely nearly 2.5 million years ago.
“There really hasn’t been any good explanation for the marine megafaunal extinction,” Melott said. “This could be one. It’s this paradigm change—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.”
The paper was co-authored by Brazilian researchers Franciole Marinho of Universidade Federal de Sao Carlos and Laura Paulucci of Universidade Federal do ABC.