| 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 Jiangshanian is a second stage of the Furongian series, corresponding to the Jiangshanian age of the Furongian epoch. It lasted from approximately 494 Ma to around 489.5 Ma (million years ago). It is preceded by the Paibian and is followed by the Stage 10.
It corresponds to Iverian stage from the regional Australian chart and, roughly, to Aksaian stage from the regional charts of Kazakhstan and Russia.
Definition[]
The GSSP of the Jiangshanian stage was ratified in 2011. The lower boundary is fixed at the base of an 8 cm thick layer of dark gray calcisiltites 108.12 m above the base of the Huayansi Formation in Duibian B Section, Zhejiang Province, China, and related to the first appearance of agnostoid arthropod Agnostotes orientalis.[2]
Jiangshanian life[]
The Jiangshanian biota, like the Paibian, is not well known. Brachiopods, trilobites and agnostids are the predominant fossils of this age. The researchers speculate that the oceans at that time remained low on oxygen, which may explain the lack of biodiversity.
Pagodia
Peratagnostus fossil
Brachiopods, organisms somewhat similar to bivalves, lived in the soil in the shelf zone. Jiangshanian genera include Apheoorthis, Aboriginella, Quadrisonia, Experilingula and Zhanatella. Various trilobites inhabited the seas. Corynexochid (Pagodia, Aksayaspis, Ceronocare, Hapsidocare), lichid (Archikainella, Eoacidaspis), asaphid (Haniwa, Haniwoides, Yuepingia, Tamdaspis), ptychopariid (Onchonotellus, Irvingella, Pseudacrocephalaspina, Tolstotchichaspis), olenid (Lauzonella, Maladioidella, Acrocephalaspina, Parabolina) and other trilobites are known from this stage. Agnostids, smaller relatives of trilobites, were still common. Jiangshanian genera include Rhaptagnostus, Eurudagnostus, Lotagnostus, Peratagnostus, Lisogoragnostus and many others. By this time, Hurdiidae remained the only family of radiodonts. Rare fossils of these filter-feeding animals have been found in Jiangshanian sediments of China and Poland.
Conodonts like Westergaardodina, Coelocerodontus and Prooneotodus were the most numerous group of chordates.
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.