Cambrian Stage 3

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Key events in the Cambrian
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-550 —
-540 —
-530 —
-520 —
-510 —
-500 —
-490 —
"Stage 3"
 
 
 
 
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Baykonur
glaciation
Baykonur
glaciation
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Orsten Fauna
Archaeocyatha extinction
SSF diversification, first brachiopods & archaeocyatha
Treptichnus pedum trace
Large negative peak δ 13Ccarb excursion
First Cloudina & Namacalathus mineral tubular fossils
Stratigraphic scale of the ICS subdivisions and Precambrian/Cambrian boundary.

Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base or top have been formally defined yet. The lower boundary is loosely defined as the first appearance of trilobites which happened around ~521 million years ago. The upper boundary and beginning of Cambrian Stage 4 is informally defined as the first appearance of the trilobite genera Olenellus or Redlichia around ~514 million years ago.[1]

Naming[edit]

The International Commission on Stratigraphy has not officially named the 3rd stage of the Cambrian. Sometimes this stage is referred to as "Atdabanian" which is used by geologists working in Siberia.[2]

Biostratigraphy[edit]

The oldest trilobites known is Lemdadella which appears at the beginning of the Fallotaspis zone.[3]

References[edit]

  1. ^ "GSSP Table - Paleozoic Era". Retrieved 18 November 2012. 
  2. ^ "The 13th International Field Conference of the Cambrian Stage Subdivision Working Group". Episodes 31 (4): 440–441. 
  3. ^ Yuan, J.L.; Zhu, X.J.; Lin, J.P.; Zhu, M.Y. (22 September 2011). "Tentative correlation of Cambrian Series 2 between South China and other continents". Bulletin of Geosciences: 397–404. doi:10.3140/bull.geosci.1274. Retrieved 23 November 2012. 


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