| System (period) | Series | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Ordovician | Lower | Tremadocian | 485.4±1.9 | |
| Cambrian | Furongian | Stage 10 | ~489.5 | |
| Jiangshanian |  ~494
| |||
| Paibian | ~497
| |||
| Miaolingian | Guzhangian | ~500.5
| ||
| Drumian | ~504.5
| |||
| Wuliuan | ~509
| |||
| Series 2 | Stage 4 | ~514 | ||
| Stage 3 | ~521 | |||
| Terreneuvian | Stage 2 | ~529 | ||
| Fortunian | 538.8±0.2
| |||
| Ediacaran | older | |||
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | ||||
The Wuliuan is a first stage of the Miaolingian series, corresponding to the Wuliuan age of the Miaolingian epoch. It lasted from approximately 509 Ma to around 504.5 Ma (million years ago). It is preceded by the unnamed Age 4 of the unnamed Epoch 2 and is followed by the Drumian age of the Miaolingian.
Definition[]
The GSSP of the Wuliuan stage was ratified in 2019. The lower boundary is fixed in the Wuliu-Zengjiayan section in Jianhe County, China, and related to the first appearance of the trilobite species Oryctocephalus indicus.[2]
Wuliuan life[]
Life in the seas continued to actively evolve. Various echinoderms (Cymbionites, Peridionites), hyoliths (Loculitheca, Foersteotheca, Yalarrnga) and brachiopods (Prototreta, Aphelotreta, Eothele) are known from the Wuliuan strata. The snail-like helcionelloids, such as Mellopigma, crawled along the bottom of the sea. Bottom graptolites, especially Sphenoecium, have reached large numbers.[3]
Zacanthoides fossils
Arthropods reached the greatest diversity in this age. Various bradoriids (Bradoria, Zepaera, Monasterium) and ostracods (Svealuta, Flemingia) were found in the Wuliuan sediments of Queensland, Australia. Trilobites of the orders Ptychopariida (Chansia, Achlysopsis, Syspacephalus) Corynexochida (Oryctocephalites, Zacanthoides, Glossopleura) and Redlichiida (Xystridura) inhabited the shelf zones in large numbers. Agnostids, close relatives of trilobites, were also numerous. Wuliuan genera include Peronopsis, Pagetia and Pentagnostus. At least some agnostids could live a pelagic lifestyle. Small and large species of Sidneyia hunted in water column while Cambroraster, a radiodont, was possibly a filter-feeder. Free-living Isoxys and Tuzoia were basal arthropods. Their wide carapaces provided reliable protection from predators.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Paleozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=77.
- ↑ Jörg Maletz (2023). "Benthic graptolites (Graptolithina, Pterobranchia) in the Miaolingian (Cambrian Series 3)". Palaeobiodiversity and Palaeoenvironments. doi:10.1007/s12549-023-00595-x