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单词 Tommotian
释义

Tommotian

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Tommotian and Burgess Shale formations give clues about Precambrian evolution.

早间,Tommotian和伯吉斯页岩化石群为前寒武纪进化提供了线索。

英语百科

Cambrian Stage 2

(重定向自Tommotian)
Key events in the Cambrian
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Ordovician
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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
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Orsten Fauna
Burgess Shale
Kaili biota
Archaeocyatha extinction
Emu Bay Shale
Sirius Passet biota
Chengjiang biota
First Trilobites
SSF diversification, first brachiopods & archaeocyatha
First halkieriids, mollusсs, hyoliths SSF
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.

Stage 2 of the Cambrian is the unnamed upper stage of the Terreneuvian series. It lies on top of the Fortunian and below Stage 3 of the Cambrian. It is commonly referred to as the Tommotian, after the Cambrian stratigraphy of Siberia. Both the upper and lower boundary have not been clearly defined yet by the International Commission on Stratigraphy. Proposals for the lower boundary are the appearance of Small Shelly Fossils, an archaeocyathid species or the mollusc Watsonella crosbyi around ~529 million years ago. The proposed upper boundary might be the first appearance of trilobites around ~521 million years ago.

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更新时间:2025/6/18 21:52:28