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单词 Pachyceras
释义

Pachyceras

英语百科

Pachyceras

Pachyceras is a perisphinctoid ammonite genus from the Middle Jurassic, upper Callovian stage, and is the type genus for the family Pachyceratidae. The shell is involute, subglobular, with a deep umbilicus and flattened flanks that slope toward a more narrowly rounded venter, and covered by low, widely spaced ribs.

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