Cambrian Stage 4 (1 янв 514500000 г. до нашей эры – 1 янв 506500000 г. до нашей эры)

Описание:

Cambrian Stage 4 is the still unnamed fourth stage of the Cambrian and the upper stage of Cambrian Series 2. It follows Cambrian Stage 3 and lies below the Wuliuan. The lower boundary has not been formally defined by the International Commission on Stratigraphy. 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 514.5 million years ago. The upper boundary corresponds to the beginning of the Wuliuan.

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