Cambrian Stage 4

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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N
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p
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P
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Ediacaran

C
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Ordovician

T
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S
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2

S
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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.

Cambrian Stage 4 is the still unnamed 4th stage of the Cambrian and the upper stage of the 2nd Cambrian series. It follows the 3rd stage and lies below the Cambrian Stage 5. The lower boundary has not been formally defined by the International Commission on Stratigraphy yet. One proposal is the first appearance of two trilobite genera, Olenellus or Redlichia. Another proposal is the first appearance of the trilobite species Arthricocephalus chauveaui. Both proposals will set the lower boundary close to ~514 million years ago. The upper boundary corresponds to the beginning of Cambrian Stage 5 which also has not been formally defined yet. Proposals are the first appearances of the trilobite species Oryctocephalus indicus or Ovatoryctocara granulata, dated at approximately ~509 million years ago.

Naming

The International Commission on Stratigraphy has not named the 4th stage of the Cambrian yet. In the widely used Siberian nomenclature stage 4 would overlap with parts of the Botomian and Toyonian.

Biostratigraphy

The beginning of Cambrian Stage 4 has been tentatively correlated with the base of the European Duyunian faunal stage and the base of the South China Leonian faunal stage.