Madrid – Millions of years after its extinction, there is still debate about what caused the dinosaurs’ disappearance. Now, a new study reinforces the idea that the main reason was the impact of an asteroid, which created an uninhabitable world for these animals, and not the effect of volcanoes.
The collision of the asteroid Chicxulub off the coast of Mexico 66 million years ago is traditionally considered to be the cause of the extinction of all dinosaur species except those that fly.
However, in recent years, some researchers have suggested as a culprit a large episode of volcanism that occurred in the Deccan Traps (India), for tens of thousands of years, which killed 75% of terrestrial species and, therefore, It could also have been done with dinosaurs.
A study published by PNAS suggests that only the impact of the asteroid could have created unfavorable conditions for dinosaurs worldwide.
In addition, large-scale volcanism could even have helped life recover after the Chicxulub impact, according to researchers at Imperial College London and the University of Bristol who sign the text.
The lead author of the research, Alessandro Chiarenza, explains that the asteroid caused an eternal winter for decades, which “ended up with the right environments for dinosaurs to live in.”
However, “the effects of the intense volcanic eruptions were not strong enough to alter the global sustainability of ecosystems.”
“Our study confirms, for the first time in a quantitative way, that the only plausible explanation for the extinction” is the long winter that followed the impact of the asteroid, which “eradicated dinosaur habitats worldwide,” he adds.
The asteroid’s impact released particles and gases into the upper layers of the atmosphere, which blocked sunlight for decades, causing a permanent winter, the researchers explain.
Volcanic eruptions also produce particles and gases that blind sunlight, but also release carbon dioxide. A combination that, in the short term, can create a volcanic winter, but in the long term, when only CO2 remains and accumulates in the atmosphere, it warms the planet.
To determine which factor – asteroid or volcanism – had more power for climate change, they used methods such as geological markers and mathematical models, which they combined with information on the environmental factors – precipitation and temperature – that dinosaurs needed to thrive.
The authors studied where on Earth, after the impact of a large meteorite or a major episode of volcanism, the conditions these animals needed to survive could continue to exist.
The models indicated that the impact of an asteroid erased all potential habitats in the world, while volcanism left some viable regions for these animals around the equator.
Also, The team believes that the long-term effects of the volcanic episode helped restore life on Earth.
The models used in the study suggest that, after a drastic global winter caused by the asteroid’s impact, the CO2-warming from the volcanism may have helped restore many habitats from the effects of the meteorite.
Chiarenza points out that the warming caused by the volcano “helped boost the survival and recovery of plants and animals.”
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