Cambrian Stage 5

Key events in the Cambrian

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-550 —

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-540 —

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-530 —

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-520 —

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-510 —

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-500 —

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-490 —

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Ediacaran

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Ordovician

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2

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3

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Fortunian

"Stage 2"

"Stage 3"

"Stage 4"

"Stage 5"

Drumian

Guzhangian

Paibian

Jiangshanian

"Stage 10"

 

 

 

 

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Baykonur
glaciation

Baykonur
glaciation

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Orsten Fauna

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Burgess Shale

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Kaili biota

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Archaeocyatha extinction

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Emu Bay Shale

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Sirius Passet biota

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Chengjiang biota

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First Trilobites

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SSF diversification, first brachiopods & archaeocyatha

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First halkieriids, mollusсs, hyoliths SSF

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Treptichnus pedum trace
Large negative peak δ 13C_carb excursion

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First Cloudina & Namacalathus mineral tubular fossils

Stratigraphic scale of the ICS subdivisions and Precambrian/Cambrian boundary.

Stage 5 of the Cambrian is the first stage of the 3rd series of the Cambrian (or Middle Cambrian). Its lower boundary has not been formally defined by the ICS yet. The most promising definition is the first appearance of either the trilobite species Oryctocephalus indicus or Ovatoryctocara granulata which is currently estimated to be around ~509 million years ago.^[1] The end of Cambrian Stage 5 and the beginning of the Drumian stage is marked by the first appearance of the trilobite Ptychagnostus atavus around ~504.5 million years ago.^[2]

Naming

The International Commission on Stratigraphy has not officially named the 5th stage of the Cambrian. A likely candidate for the name is "Molodian", named after the river Molodo in Bulunsky District, Sakha Republic, Russia.^[3]

GSSP

Three sections are currently discussed as GSSP candidates: the Wuliu-Zengjiayan section near Balang in Guizhou province (China), a section on Split Mountain in Nevada (USA)^[2] and the "Molodo river section" along the Molodo river.^[3] The Wuliu-Zengjiayan section is an outcrop of the Kaili Formation in the Wuliu quarry. The first candidate for the beginning of Stage 5 is the trilobite Oryctocephalus indicus, the second candidate is the trilobite Ovatoryctocara granulata. ^[4]

References

1. Gozalo, Rodolfo; Álvarez, María Eugenia Dies; Vintaned, José Antonio Gámez; Zhuravlev, Andrey Yu.; Bauluz, Blanca; Subías, Ignacio; Chirivella Martorell, Juan B.; Mayoral, Eduardo; Gursky, Hans-Jürgen; Andrés, José Antonio; Liñán, Eladio (1 December 2011). "Proposal of a reference section and point for the Cambrian Series 2-3 boundary in the Mediterranean subprovince in Murero (NE Spain) and its intercontinental correlation". Geological Journal: n/a–n/a. doi:10.1002/gj.1330.
2. "GSSP Table - Paleozoic Era". Retrieved 15 November 2012.
3. "The 13th International Field Conference of the Cambrian Stage Subdivision Working Group" (PDF). Episodes 31 (4): 440–441.
4. Sundberg, F.A.; Zhao, Y.L.; Yuan, J.L.; Lin, J.P. (22 September 2011). "Detailed trilobite biostratigraphy across the proposed GSSP for Stage 5 ("Middle Cambrian" boundary) at the Wuliu-Zengjiayan section, Guizhou, China". Bulletin of Geosciences: 423–464. doi:10.3140/bull.geosci.1211.

Preceded by Proterozoic Eon	Phanerozoic Eon
	Paleozoic Era						Mesozoic Era			Cenozoic Era
	Cambrian	Ordovician	Silurian	Devonian	Carboniferous	Permian	Triassic	Jurassic	Cretaceous	Paleogene	Neogene	4ry