Cambrian Stage 2
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.[1] Both the upper and lower boundary have not been clearly defined yet by the International Commission on Stratigraphy.[2] 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.[2] The proposed upper boundary might be the first appearance of trilobites around ~521 million years ago.[2]
Possible candidates for a GSSP include the first appearance of Watsonella crosbyi in the Zhujiaqing Formation in Yunnan, China or the Pestrotsvet Formation near the Aldan River on the Siberian Platform.[3]
References
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Paleozoic Era | |||||
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Cambrian | Ordovician | Silurian | Devonian | Carboniferous | Permian |
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