bya

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中文释义

英文释义

符号
  1. Abbreviation of billion years ago (A symbol for a unit of measure.); Synonym of Gya (“billion years ago (short scale): 10⁹ years ago”). usually
    — The first (oldest) unit of time is the Precambrian Supereon, which covers much of Earth's history from its origins roughly 4.55 bya to 545 mya. Very primitive, one-celled life-forms arose as early as 4.0 bya and near the end of the era (570 mya) the oldest known fossils of multi-celled organisms appear.
  2. Abbreviation of billion years ago (A symbol for a unit of measure.); billion years ago (long scale):10¹² years ago: a trillion years ago (short scale). dated,uncommon
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