Demise Of Dinosaurs Blamed On Double Catastrophe

Dinosaurs were wiped out 66 million years ago by not just one but two natural disasters, new research from the United States suggests.

As well as a six-mile wide meteor smashing into Earth, scientists believe that the dinosaur population was finished off by a surge in volcanic activity in a mountainous region of India, known as the Deccan Traps.

The research, published in the journal Science, suggests that the impact of the meteor crash turned up the heat of the volcanoes.

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 at Berkeley (UC Berkeley), 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 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.

Co-author Professor Mark Richards, also from UC Berkeley, said: "If our high-precision dates continue to pin these three events - the impact, the extinction and the major pulse of volcanism - closer and closer together, people are going to have to accept the likelihood of a connection among them.

"The scenario we are suggesting - that the impact triggered the volcanism - does in fact reconcile what had previously appeared to be an unimaginable coincidence."

He pointed out that a large nearby earthquake similar in size to the one that struck Japan in 2011 could also have re-ignited the Deccan Trap volcanoes.

In fact it was possible that large earthquakes had triggered volcanic eruptions throughout the Earth's history.

But in this case it appeared much more likely that a meteor impact rather than an earthquake set off the volcanic surge.