| 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] | ||||
Stage 4 is an unnamed upper stage of the Cambrian Series 2, corresponding to the Stage 4 age of the Series 2 epoch. It lasted from approximately 514 Ma to around 509 Ma (million years ago). It is preceded by the Stage 3 age of the Series 2 and is followed by the Wuliuan age of the Miaolingian. GSSP and naming have not yet been chosen for this stage.
Definition[]
The GSSP of Stage 4 has not yet been accepted and there are no sections selected as candidates. Stratigraphers propose the first appearance of trilobite genera Olenellus or Redlichia as a marker of the lower boundary.[2]
Coincidences with regional stages[]
Some regional stages overlap partially or completely with Stage 4. From upper to lower:
Siberia:[3]
- Amgan/Solvan (lower part)
- Toyonian
- Botomian (upper part)
North America:[4]
- Delamaran (lower part)
- Dyeran (upper part)
Australia:[5]
- Ordian (lower part)
West Avalonia:[6]
- Branchian (upper part)
China:[7]
- Duyunian
Life during Stage 4 age[]
Life was concentrated in the shallow waters of the sea. Various archaeocyathan sponges (Arrythmocricus, Retilamina, Metaldetes, Robertiolynthus) formed the first reefs. Brachiopods like Eothele lived in the sea soil. Stenothecoids (Stenothecoides, Cambridium), suspension feeders that lived exclusively in Cambrian, may be related to brachiopods or bivalves. Snail-like helcionelloids (Yochelcionella, Latouchella, Pelagiella) lived lived on the seabed. Worms like Ottoia and Selkirkia waited for prey, buried in the sand. The relationships of some animals of that time are unclear. One of such creatures is Salterella, which had a cone-shaped shell.
Olenellus thompsoni
Perspicaris
The flowering of arthropods continued. Various trilobites like Protolenus, Perissopyge, Xandarella, Wanneria, Olenellus and Mesonacis, crawled along the bottom in search of food. Agnostids like Tannudiscus, Ladadiscus, Cobboldites, Cephalopyge and Pseudocobboldia, looked like trilobites, but had a more pronounced posterior part of the body and swam in the water column. Anomalocaris, a radiodont, hunted by tracking prey with large compound eyes and using its front appendages to attack. Some arthropods, such as Perspicaris and Tuzoia, used wide carapaces for camouflage and protection from the claws and teeth of predators.
Among vertebrates, conodonts were the most numerous. Amphigeisina was found in the Botomian Shabakty Formation of Kazakhstan.
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.
- ↑ https://paleobiodb.org/classic/displayTimescale?interval=Toyonian
- ↑ https://paleobiodb.org/classic/displayTimescale?interval=Dyeran
- ↑ https://paleobiodb.org/classic/displayTimescale?interval=Ordian
- ↑ https://paleobiodb.org/classic/displayTimescale?interval=Branchian
- ↑ https://paleobiodb.org/classic/displayTimescale?interval=Duyunian