Did coal fires contribute to biggest extinction ever?

excerpt:

Many factors combined to cause the mass extinction at the end of the Permian period 251 million years ago, during which about 96 per cent of marine species and 70 per cent of those on land went extinct. Several researchers have speculated that volcanism might have set off extensive coal fires that contributed to the extinction, but no clear evidence had been found – until now.




http://www.newscientist.com/article/dn20016-did-coal-fires-contribute-to-biggest-extinction-ever.html