What caused the Great Dying of life on this planet 250 million years ago? People once believed it to be a one-time job probably by an extraterrestrial body crashing into the earth. However, research findings by experts at China University of Geosciences in Wuhan propose that the mass biotic extinction was accomplished in at least two stages.

The section plane of the Changxing coalmine in Zhejiang province is a representative site which records the Great Dying 250 million years ago. After studying the molecular fossil near the borderline between the Permian period and Triassic period at the coalmine, professor Xie Shucheng and academician Yin Hongfu together with British experts discovered at least two biotic crises.

Xie Shucheng believes studies of the coalmine can show the mass extinction that happened 250 million years ago had multiple phases with the primary cause pinpointed on the earth itself rather than from outside the earth. The research findings have been published on the renowned science magazine Nature.

(People's Daily January 25, 2006)