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aptychus

noun
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ap·​ty·​chus | \ ˈaptə̇kəs \
plural aptychi\ -​ˌkī \

Definition of aptychus

: a shelly plate usually of two pieces found in ammonites and regarded as an operculum

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History and Etymology for aptychus

New Latin, from a- entry 2 + Greek ptychē fold

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“Aptychus.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/aptychus. Accessed 29 January 2020.

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