Washington, Dec 13 (ANI): A new theory has suggested that the mass extinction event that killed the dinosaurs 250 million years ago, was caused by the Earth's magnetic field going into complete disarray, exposing the planet to a shower of cosmic radiation.
According to a report in Discovery News, the theory has been put forward by Yukio Isozaki of the University of Tokyo.
The Permian-Triassic mass extinction event happened 250 million years ago, snuffing out 90 percent of life on the planet.
Now, the new theory by Isozaki suggests that the catastrophe was set in motion 15 million years earlier, deep in the Earth.
On the edge of the molten outer core, a plume of super-hot material began rising through the mantle, upsetting convection in the core and throwing the planet's magnetic field into disarray.
The weakening of Earth's magnetic field exposed the surface to a shower of cosmic radiation, according to Isozaki. He believes that the radiation broke nitrogen in the atmosphere into ions that acted as seeds for clouds enshrouding the planet.
"This would've caused severe cooling and a drop in sea level" as the cool temperatures allowed massive ice sheets to accumulate on the continents, Isozaki said.
"If you check the rock record at that time, tropical coral reefs die first. Then, you start to see fauna from mid latitudes move into the tropics. It all points to cooling," he added.
The superplume disrupted the magnetic field and put a strain on creatures living on the surface, but it was only the beginning.
According to Isozaki, five million years later it reached the surface, and the hot material punched through the crust, erupting as three successive supervolcanoes.
Today, the remnants of those volcanoes are scattered through India, China and Norway.
On their own they were too small to do much harm, but together, they cooled the climate even further, launching an extinction as bad as the one that would kill the dinosaurs 185 million years later.
Then, 10 million years later, the Permian-Triassic extinction struck.
"The effects of the superplume were just the first punch of extinction," Isozaki said. "Then came the knockout punch, the Permian-Triassic extinction," he added.
Isozaki said that both "punches" were caused by the same superplume.
Ten million years after the smaller volcanoes blew their tops, a much larger volcano, the Siberian Traps, erupted, launching the worst killing in the planet's history. (ANI)