Dinosaur extinction blamed on two back-to-back catastrophic events

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A dual punch of asteroid or comet impact followed by extreme volcanic activities are to blame for extinction of large number of species including dinosaurs, a new study has suggested.

The research that led to the conclusion was a result of decades-old argument of what caused the extinction of the dinosaurs 66 million years ago. Asteroid impact and extreme volcanic activities have always been the two most favoured theories, but scientists have always been at loggerheads on what could have been the nail on the coffin.

The debate has been raging on for last 35 years with one group claiming that there was no role of volcanic eruptions while the other side of the aisle claiming asteroid impact was just a blip in a long-term die-off.

New evidence unearthed by University of California, Berkeley scientists now suggest that asteroid/comet impact effectively upped the volcanic activity and this dual blow led to the extinction of hundreds of thousands of animal and plant species.

Analysis of evidence unearthed from India’s Deccan traps reveal that the lava flows, which at the time were erupting at a slower pace, doubled in output within 50,000 years of the asteroid or comet impact that is thought to have initiated the last mass extinction on Earth.

UC Berkeley scientists claim that their findings suggest that it would be rather ‘artificial to distinguish between them as killing mechanisms’ because both the events effectively worked together to annihilate the dinosaurs.

Lead researcher Paul Renne, a UC Berkeley professor-in-residence of earth and planetary science and director of the Berkeley Geochronology Center says: “It is going to be basically impossible to ascribe actual atmospheric effects to one or the other. They both happened at the same time.”

Volcano plumbing system affected

An asteroid or comet strike as hypothesized by many scientists through several state-of-the-art models show that an impact will effectively give rise to plumes of dust that will act as a blanket blocking the sunlight. But this wasn’t the only factor that played a hand in extinction of dinosaurs.

The impact effectively changed the internal plumbing system of volcanoes and accelerated the volcanic activities and brought about major changes in the chemistry and frequency of eruptions. The eruptions started lasting longer and sent out more and more ash, dust, and toxic fumes into the atmosphere.

These things delayed recovery of life for 500,000 years after the KT boundary, the term for the end of the Cretaceous and the beginning of the Tertiary period when large land animals and many small sea creatures disappeared from the fossil record.

Co-author Mark Richards, a UC Berkeley professor of earth and planetary science and the one who originally proposed that the comet or asteroid impact reignited the Deccan Traps lava flows, says “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.”