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词条 Rhynchotrema
释义
Rhynchotrema
fossil genus
extinct genus of brachiopods, or lamp shells, found as fossils in Middle and Late Ordovician rocks (the Ordovician Period lasted from 505 to 438 million years ago). The shell is small and distinctive for its strongly developed ribbing. Rhynchotrema is a useful Ordovician index, or guide, fossil.
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更新时间:2025/4/7 18:03:31