The Chinese and US scientists may be able to unveil the mystery of the mass extinction that swept the earth 250 million years ago, through a joint study on a world-famous stratotype section in southern China.

With abundant fossils, which have remained intact despite the passage of time, the Penglaitan Section in Laibin County, Guangxi Zhuang Autonomous Region, will hopefully be identified as a global stratotype section and point (GSSP), also known to scientists as a "golden spike", say a group of scientists during an ongoing site survey.

"Golden spike" is a metaphor to describe GSSP as a universally accepted yardstick that divides the global strata and tells their years.

The scientists, led by Shen Shuzhong, professor with Nanjing Institute of Geology and Paleontology under the Chinese Academy of Sciences (CAS), and Sam Bowring, professor with Massachusetts Institute of Technology, have been collecting samples over the past days from the section, which stands a dozen meters high on the bed of the Hongshui River as its water has subsided in the dry season.

The landmark section has been visited by worldwide scientists since it was discovered in the 1930s. Experts say its intact biostratum is "extremely rare" in a Permian stratum, which dates 250 million to 300 million years from today.

Meishan Section, a stratotype section in Changxing County of east China's Zhejiang Province, was confirmed by International Union of Geology Science last year to be a golden spike that divides the Permian and Triassic.

Many Chinese and foreign scientists believe the Penglaitan Section will possibly be identified as another "golden spike" toward the end of the Permian.

"Actually, it has been included as a candidate GSSP by an international stratigraphy organization," said Cao Changqun, an associate researcher with the Nanjing institute.

The ongoing site survey of the scientists aims to collect more samples from the section for further study, so as to provide more evidence to underpin the hypothesis.

It is said that the mass extinction, a catastrophe more devastating than the extinction of dinosaurs from earth, caused 90 percent of marine life and 70 percent of onshore life to disappear as it swept the earth.

Jin Yugan, a CAS academician and a research fellow with the Nanjing institute, has suggested the mass Permian-Triassic extinction is a "sudden, all at once occurrence" rather than a gradual one as it was thought to be.

His conclusion was based on years of study on the Meishan Section. In a thesis published in a 2000 issue of the US Science magazine, Jin challenged the "survival of the fittest", a traditional theory raised by Charles Darwin.

Jin and his colleagues will further support the argument with more findings in their future research.

(Xinhua News Agency April 5, 2002)