Placodermi(redirected from Aphetohyoidea)
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a class of extinct fishes that lived during the Devonian. Their length was up to 5–6 m. The head and anterior part of the trunk were covered with an armor of bony plates of cutaneous origin. The plates were nodular and ridged. The head and trunk sections of the armor were articulated, and the jaws consisted of pointed bony plates. There were two subclasses: Arthrodira and Antiarchi (which included the genus Bothriole-pis).