Mega-Volcanic Eruptions Linked to Pre-Dinosaur Extinction

Scientists announced new research on Friday which linked the abrupt disappearance of half of earth's species 200 million years ago to a precisely dated set of gigantic volcanic eruptions.

Scientists say gases released during the End-Triassic Extinction (ETE) may have led to sudden and dramatic extinctions, partly a result of climate changes. The vast die-off may have paved the way for dinosaurs to evolve and dominate the planet for the next 135 million years. The exact mechanism about the extinction of these massive animals was not known although.

"This may not quench all the questions about the exact mechanism of the extinction itself." said the study's coauthor Paul Olson, a geologist at Columbia University's Lamont-Doherty Earth Observatory. "However, the coincidence in time with the volcanism is pretty much ironclad."

The decay of uranium isotopes was used to note the exact dates from a rock called basalt, which was left by the eruptions. "This may not quench all the questions about the exact mechanism of the extinction itself. However, the coincidence in time with the volcanism is pretty much ironclad", added Olson.

Scientists have recently begun suggesting that the so-called End-Triassic Extinction and at least four other known past die-offs were caused at least in part by mega-volcanism and resulting climate change. However, they were unable to tie deposits left by eruptions to biological crashes closely in time. This study provides the tightest link yet, with a newly precise date for the ETE--201,564,000 years ago, exactly the same time as a massive outpouring of lava.

Lead author Terrence Blackburn (then at Massachusetts Institute of Technology; now at the Carnegie Institution) used the decay of uranium isotopes to pull exact dates from basalt, a rock left by eruptions. The basalts analyzed in the study all came from the Central Atlantic Magmatic Province (CAMP), a series of huge eruptions known to have started around 200 million years ago, when nearly all land was massed into one huge continent.