[4] It lasted from about 506.5 to 497 million years ago and is divided in ascending order into 3 stages: the Wuliuan, Drumian, and Guzhangian.

The most promising fossil markers were seen to be the respective first appearances of either trilobite species Ovatoryctocara granulata or Oryctocephalus indicus,[6] which both have an age close to 506.5 million years ago.

[5] After some deliberation, the FAD of Oryctocephalus indicus was chosen to be the lower boundary marker, and the GSSP was placed in the Kaili Formation, Wuliu-Zengjiayan, Guizhou, China.

In particular, trilobites of the families Ollenellidae and Redlichiidae have been extinct in Laurentia and South China, respectively.

The most common Wuliuan graptolite genus is Sphenoecium, whose robust colonies were found all over the world.