The Global Stratotype Section and Point (GSSP) for the base
of the Triassic and hence the Permian-Triassic/Paleozoic-Meso-
zoic boundary has been formally established and ratified by the
International Union of Geological Sciences (IUGS)'at Section D,
Meishan, Changxing County, Zhejiang Province, China (Yin et al.,
1996, Yin et al., 2001, Tong and Yin, 2001).  This boundary is de-
fined by the first appearance of the conodent species Hindeodus
parvus (Kozur & Pjatakova) in Bed 27c at the Meishan D section
and is estimated to have an age of ~253 Ma based on single zircon
U/Pb analyses of the bracketing ash beds.