ostracoderm

Any of various extinct primitive jawless fishes of the Ordovician through the Devonian periods, having bodies encased in an armor of bony plates.

Having a bony skin like a coat of mail; ostraciont, as a fish; pertaining to the Ostracodermi. Also ostracodermal, ostracodermous.

An ostraciont fish, as a member of the Ostracodermi; a plectognath of the suborder Ostracodermi.

Any of several extinct fishlike jawless vertebrates having a heavily armored body; of the Paleozoic.

extinct fish-like jawless vertebrate having a heavily armored body; of the Paleozoic