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| os·tra·co·derm [ óstrəkō dùrm ] (plural os·tra·co·derms) |
noun |
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| Definition: |
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extinct jawless fish: an extinct, jawless, mainly freshwater fish, dating from the Silurian and Devonian periods, that had a flat body encased in a layer of protective bony plates and scales
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| [Late 19th century. < Greek ostrakon "hard shell"] |
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