According to a study, mega volcanic eruptions may be ruled as the cause of massive pre-dinosaur extinction.
A new study conducted by Columbia University's Lamont-Doherty Earth Observatory found that mega volcanic eruptions could have wiped out half of earth's species 200 million years ago.
"This may not quench all the questions about the exact mechanism of the extinction itself." said the study's co-author, Paul Olson, a geologist at Columbia University's Lamont-Doherty Earth Observatory. "However, the coincidence in time with the volcanism is pretty much ironclad."
According to scientists, gases that were released during the End-Triassic Extinction (ETE) could have led to the sudden and dramatic extinctions, partly a result of climate changes. The occurrence of massive numbers of deaths could have led to the evolution of dinosaurs that eventually began dominating the planet for the next 135 million years.
Previous studies have shown that mega-volcanism and the resulting climate change had caused the ETE and at least four other extinctions. However, they were not able to show that the extinctions occurred during the time of discovered geological deposits. Now, according to geologists, this new study shows a direct link between mega-volcanism and pre-dinosaur extinctions.
"By correlating the precisely dated basalts with surrounding sedimentary layers, the new study shows that precession operated pretty much the same way then, allowing dates with a give or take of 20,000 years to be assigned to most sediments holding fossils," Olsen said.
Lead author of the study, Terrence Blackburn of the Carnegie Institution, used the decay of uranium isotopes to pull exact dates from basalt, a rock known to have been left by eruptions. Researchers analyzed samples from Nova Scotia, Morocco, and even the suburbs of New York City.
"Zircon is a perfect time capsule for dating those rocks," said Blackburn. "When the mineral crystallizes, it incorporates uranium, which decays over a known time with respect to the element lead. By measuring the ratio of uranium to lead in our samples, we can determine the age of those crystals."
The study is published in the journal Science.
