So what really killed the dinosaurs: the impact of asteroids or a series of volcanic eruptions?

Like the old adage of chicken or egg, scientists have wondered for decades what happened first: devastating impact of asteroids or suffocating series of volcanic eruptions? A pair of two studies published in Science decided to answer that very question.

First of all, let 's go back 30 years. In the 1980s, researchers proposed that the Chixculub impact crater located on the Yucatan Peninsula in Mexico is the landing site of an asteroid responsible for the destruction of the dinosaurs. The scientific world has been upset. Was it the asteroid or the volcanic eruptions? A combination of both?

By adopting a more precise approach than the previous methods, the new studies lead us to the traps of the Deccan, one of the largest volcanic chains on the planet.. Using two different dating methods, both studies agree that volcanic eruptions probably contributed to the massive extinction that destroyed non-avian dinosaurs. The results suggest that this volcanic chain broke out over a million years, beginning about 400,000 years before the impact of Chixculub and ending around 600,000 years after the Cretaceous.

This is where it becomes gritty. A UC-led team in Berkeley said Deccan traps had begun to erupt more and more over the last 100,000 years, placing already stressed ecosystems in a difficult situation to recover even before Asteroid does not hit. Princeton researchers say, however, that the majority of eruptions occurred after the impact and that the asteroid was the disappearance of the dinos.

Berkeley researchers conducted argon-argon dating to measure when lava flow occurred. They discovered that nearly three quarters of the lava found at the Deccan site had burst 600,000 years after the impact, indicating that an asteroid might have caused an acceleration of eruptions, which then delayed any hope of ecological recovery. The central point of this theory is that large quantities of gas likely to lead to climate change were released before the extinction event.

On the other hand, Princeton researchers have made a dating of uranium-lead on zircon crystals found in cooled magma from nine formations. Their timing suggests that Deccan traps broke out after four 100,000-year events, releasing greenhouse gases and magma at the same time – such as when an asteroid was hit – resulting in increased climate change. A limitation of this study is that the crystals could have formed before the eruption, thus changing the course of the chronology.

"The Deccan's impact and volcanism can produce similar environmental effects, but these occur at extremely different time scales," Berkeley researcher Courtney Sprain said in a statement. "Therefore, to understand the contribution of each agent to extinction, it is essential to evaluate the timing.

Who came first? It looks like the jury is still on the issue of eruption or impact.