placoderm

[ plak-uh-durm ]

noun

1. any of various extinct jawed fishes of the class Placodermi, dominant in seas and rivers during the Devonian Period and characterized by bony armored plates on the head and upper trunk.

placoderm

/ ˈplækəˌdɜːm /

noun

1. any extinct bony-plated fishlike vertebrate of the class Placodermi, of Silurian to Permian times: thought to have been the earliest vertebrates with jaws

placoderm

/ plăk′ə-dûrm′ /

1. Any of various extinct fishes of the class Placodermi of the Silurian and Devonian Periods, characterized by bony plates of armor covering the head and flanks. The bodies of placoderms were spindle-shaped or flattened, and their skeletons were usually partially bony and included a cranium. Placoderms were the first group of fish to evolve jaws, but are not closely related to the jawed fish of today.

Word History and Origins

Origin of placoderm¹

1855–60; < New Latin Placodermi name of the class, plural of placodermus, equivalent to placo- (< Greek; placoid, -o- ) + -dermus -derm

Word History and Origins

Origin of placoderm¹

C19: from Greek plac-, plax a flat plate + -derm