It is common knowledge that a massive asteroid collided with the Earth 66 million years ago and caused the events that led to the extinction of the dinosaurs and 50% of all genera on the planet. However, it may have taken more than just the asteroid to cause the extinction event. Some scientists believe that volcanic activity assisted in creating those life-ending conditions. New research supports this idea, as the team claims to have found evidence of intense volcanism that went on for 750,000 years before, during, and after the asteroid impact, which may have contributed to the demise of the dinosaurs. The paper has been published in Science.
The study utilized samples from the Deccan Traps, a geological formation in India that has very well-preserved evidence of ancient volcanic activity. The team’s geochronological dating found that the bulk of the eruptions in that era began 250,000 years before the Chicxulub asteroid hit Mexico, and continued for 500,000 more years after. In addition to the 1.5 million square kilometers of lava that was released during this time period, high levels of volatiles entered the atmosphere, leading to the acidification of the air and water.
“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,” co-author Michael Eddy of MIT said in a press release. “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.”
The data suggest that volcanism may have played a significant role in the extinction event, but it may never be clear which factor actually provided the tipping point for the widespread die-out. Even if volcanic activity did not add enough volatiles to the environment to wipe out life on its own, it may very well have at least deteriorated conditions enough to make the asteroid’s effects more devastating.
The conversation about what killed the dinosaurs really began in 1980, when samples of iridium were found in Italy. Iridium is very rare on Earth, and is most commonly brought here by way of meteorites. This was the first indication that an asteroid killed the dinosaurs. Just over 10 years later, the Chicxulub crater was found in Mexico, supporting the asteroid theory. Prior to the asteroid theory, volcanic activity was believed to have caused the extinction event. Now, there is evidence that both may have played a role. Perhaps neither would have been sufficient on their own, but were able to cause all of the destruction by working in concert.
“We’re getting better and better at dating mass-extinction events, but we’re not having a comparable improvement in our understanding of what caused them. Now that the timing is so well-resolved, I think there will be people coming back to think about the cause with new vigor,” co-author Sam Bowring concluded.