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词条 Anchura
释义
Anchura
snail
genus of extinct marine gastropods (snails) found as fossils only in marine deposits of Cretaceous age (between 144 and 66.4 million years old). It is thus a useful guide or index fossil because it is easily recognizable. The shell whorls are globular and ornamented with raised crenulations; the spire is sharply pointed; the body whorl, the final and largest whorl, has a prominently extended outer lip.
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更新时间:2025/4/5 9:59:33