漸ぜん新しん世せい

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Meanings

1

Oligocene epoch

Geological epoch from about 33.9 to 23 million years ago, between the Eocene and Miocene.

漸ぜん新しん世せいは哺ほ乳にゅう類るいの多た様よう化かが進すすんだ時じ代だいである。
The Oligocene was a period when mammalian diversification advanced.