Dinosaurs Possibly Killed By A One-Two Punch

Brett Smith for redOrbit.com – Your Universe Online

When it comes to theories on why the dinosaurs went extinct, massive and widespread volcanic activity has always played second fiddle to the more dramatic theory of a large asteroid slamming into Earth.

However, a new study published in the journal Science has found that both of these devastating phenomena could have taken place concurrently and collectively wiped the massive lizards off the planet.

The new study is based on an analysis of rock from the Deccan Traps – an area in west-central India that contains well-preserved samples from one of the biggest volcanic events in Earth’s history. The researchers were able to determine that the ancient rocks in Deccan Traps were deposited by activity that started 250,000 years prior to the asteroid strike and extended for 500,000 years following the massive impact, releasing around 580,000 square miles of lava.

Researchers used the ratio of uranium and lead isotopes in the rock to gauge a more accurate date for when they were formed. Over 50 samples of rocks were tested independently at MIT and Princeton University.

The study’s dating of the Deccan Traps rocks is an improvement on past efforts that had attempted to do so, but were only able to narrow down the margin of error to around one million years. The new dates give support to the idea that both volcanic activity and an asteroid strike were behind the dinosaurs’ demise.

“Both are potentially really important,” study author Blair Schoene, a professor of geosciences at Princeton, told the Washington Post. “I don’t know if we can say the extinction would have or would not have happened without both of them.”

In the scenario hinted at by the new study, volcanic activity would have released large quantities of highly toxic chemicals into the air, placing most species on Earth under a high amount of stress. A huge asteroid strike would have simply finished off species that could have already been on their way out.

“I sort of favor the one-two punch idea,” Schoene said.

Study author Gerta Keller has long championed the idea of both causes leading to the Cambrian extinction. She has been seen as somewhat of a maverick in voicing this theory, and the new study serves to validate her somewhat unpopular idea.

“I think this is a game-changer,” she said. “The data is so strong at this point that the momentum is entirely on my side.”

The study team also pointed out that their research resonates with what is happening to our planet right now.

“If models of volatile release are correct, we’re talking about something similar to what’s happening today: lots of carbon dioxide being emitted into the atmosphere very rapidly,” said Michael Eddy, a planetary scientist at MIT. “Ultimately what that can do is lead to ocean acidification, killing a significant portion of plankton — the base of the food chain. If you wipe them out, then you’d have catastrophic effects.”


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