[5] Its base is defined by the first appearance of the trilobite species Oryctocephalus indicus; it ends with the beginning of the Drumian Stage, marked by the first appearance of the trilobite Ptychagnostus atavus around 504.5 million years ago.
[6] The 'golden spike' that formally defines the base of the age is driven into the Wuliu-Zengjiayan (乌溜-曾家崖) section of the Kaili formation, near Balang Village in the Miaoling Mountains, Guizhou, China.
[2] The base of Wuliuan stage (and, accordingly, the entire Miaolingian Series) is characterized by the first major extinction of trilobites, known as the Olenellid Biomere boundary.
The most common graptolite genus of this age is Sphenoecium, whose robust colonies were found all over the world.
[12] Numerous panarthropods, including trilobites, agnostoids, hurdiids and bradoriids, are known from Wuliuan deposits.