Wuliuan

Three sections were discussed as GSSP candidates: the Wuliu-Zengjiayan section near Balang in Guizhou province (China), a section on Split Mountain in Nevada (USA) and the "Molodo river section" along the Molodo river (Sakha Republic, Russia). The Wuliu-Zengjiayan section is an outcrop of the Kaili Formation in the Wuliu quarry. The first candidate for the beginning of the Wuliuan was the trilobite Oryctocephalus indicus, the second candidate was the trilobite Ovatoryctocara granulata. The Wuliu-Zengjiayan section was chosen as the formal base in 2018, with the first appearance of Oryctocephalus indicus being chosen as the defining marker for the GSSP. ==Major events==

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. This event is linked by a sudden negative carbonate carbon excursion. ==Paleontology==

Benthic graptolites have reached a considerable diversity in the Wuliuan. The most common graptolite genus of this age is Sphenoecium, whose robust colonies were found all over the world. Numerous panarthropods, including trilobites, agnostoids, hurdiids and bradoriids, are known from Wuliuan deposits. ==References==