New Delhi - The large mass extinction of Grand Dying, which occurred on the Earth about 250 million years ago, was most probably caused not by asteroid or comet but by global warming. It had wiped out 90 per cent of all marine life and nearly three-quarters of land-based plant and animal life going extinct.  

In a paper published by Science Express, the online version of the journal Science, on Friday  the researchers of the University of Washington, scientist Peter Ward said they have found no evidence for an impact at the time of "the Great Dying" 250 million years ago.

"The marine extinction and the land extinction appear to be simultaneous, based on the geo-chemical evidence we found," their paper said.

Dr. Raj Baldev, Indian Cosmo Theorist, told while addressing his  Institute Researchers of  SAROUL (Scientific Advance Research of Universe and Life) that he was agreeable to the views of Mr. Peter Ward that the mass extinction was more likely due to atmospheric warming;" the greenhouse gases might have triggered by erupting volcanoes," he said.