Dinosaurs were wiped out by a double-whammy disaster caused by a meteor impact followed by a volcanic storm, new evidence has shown.
The creatures’ 160m-year reign is said to have ended when a 9.5km wide asteroid or comet smashed into the Earth off the coast of Mexico 66m years ago, changing the climate around the world.
Some experts insist the impact was a red herring and the real reason for the mass extinction was a surge of volcanic activity in a region of India known as the Deccan Traps.
A new study looks set to end the debate by linking the two events.
Scientists believe the meteor collision shook up the Earth so much that it turned up the volcanic heat. Within 50,000 years of the impact, the Deccan Traps volcanoes doubled their output, blanketing the Earth with sulphurous gas and dust.
Together, the impact and volcanism caused a dramatic change in climate as the sun’s rays were blanketed out in a version of the “nuclear winter” predicted to follow a global nuclear war.
The evidence is based on new measurements dating layers of volcanic rock to track the progress of the Deccan Traps that were more accurate than any made before.
Lead scientist Professor Paul Renne, from the University of California, said: “Based on our dating of the lavas, we can be pretty certain that the volcanism and the impact occurred within 50,000 years of the extinction, so it becomes somewhat artificial to distinguish between them as killing mechanisms: Both phenomena were clearly at work at the same time.”
The research, published in the journal Science, suggests the impact abruptly changed the volcanoes’ “plumbing system” so that eruptions became less frequent but much more powerful.
The average rate at which fiery magma was hurled out of the Earth roughly doubled, the study showed.
These enhanced eruptions continued long after the dinosaurs died out, delaying the recovery of life for some 500,000 years after the “KT boundary”, the point in time marking the end of the Cretaceous and start of the Tertiary period.
“We are proposing that the volcanism unleashed and accelerated right at the KT boundary suppressed the recovery until the volcanoes waned,” Prof Renne said.
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