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出典:Wiktionary
出典:『Wiktionary』 (2025/10/17 15:55 UTC 版)
From Ancient Greek τόνος (tónos, “stretch”).
Tonian (not comparable)
Tonian
出典:Wikipedia
出典:『Wikipedia』 (2011/07/10 00:42 UTC 版)
The Tonian (from Greek tonas, "stretch") is the first geologic period in the Neoproterozoic Era and lasted from 1000 Mya to 850 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined by the ICS based on radiometric chronometry.