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单词 ostracoderm
释义

ostracoderm

/ɒˈstrakədəːm /
noun
An early jawless fossil fish of the Cambrian to Devonian periods, having a heavily armoured body.
  • Class Agnatha: several orders.
By the Middle Devonian the armoured jawless ostracoderms were in decline, and instead the jawed fish were undergoing a great evolutionary radiation in both the sea and in freshwater....
  • With their armored head shield and trunk shield composed of overlapping bony plates, the placoderms appear at first glance extremely similar to the ostracoderms (armoured jawless fish).
  • These were jawless, armored fish informally called ostracoderms, but more correctly placed in the taxon Pteraspidomorphi.

Origin

Late 19th century: from modern Latin Ostracodermi (former taxonomic name), from Greek ostrakon 'shell' + derma 'skin'.

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更新时间:2025/3/27 0:45:46