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placoderm

Syllabification: plac·o·derm
Pronunciation: /ˈplakədərm
 
/

Definition of placoderm in English:

noun

An extinct fish of the Devonian period, having the front part of the body encased in broad flat bony plates.
  • Class Placodermi: several orders
Example sentences
  • Such giant cephalopods play or played a similar ecological role of top predator to that of Devonian arthrodire placoderms, Mesozoic pliosaurs and Cenozoic toothed whales.
  • During this period the agnathan and gnathostome fishes, too, gave rise to many distinctive groups: the armoured ostracoderm and placoderms, the bony fishes, and elasmobranchs to populate marine and freshwater environments.
  • 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).

Origin

mid 19th century: from Greek plax, plak- 'flat plate' + derma 'skin'.

Definition of placoderm in:

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