Cambrian Stage 4
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.
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.
- Peng, S.C.; Babcock, L.E. (21 September 2011). "Continuing progress on chronostratigraphic subdivision of the Cambrian System". Bulletin of Geosciences: 391–396. doi:10.3140/bull.geosci.1273. Retrieved 21 November 2012.
- "GSSP Table - Paleozoic Era". Retrieved 18 November 2012.
- 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.
- "The 13th International Field Conference of the Cambrian Stage Subdivision Working Group". Episodes 31 (4): 440–441.
|Preceded by Proterozoic Eon||542 Ma - Phanerozoic Eon- Present|
|542 Ma - Paleozoic Era -251 Ma||251 Ma - Mesozoic Era - 66 Ma||66 Ma - Cenozoic Era - Present|