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

Example Sentences

The first is Xiushanosteus mirabilis, a tiny placoderm, a type of jawed fish that was covered in armor.

From Salon

The discovery fills in an important step in the evolution of life on Earth, according to Dr Martin Brazeau, a placoderm expert at Imperial College London, who is also independent of the Australian research team.

From BBC

There was no sign of lungs in the placoderm fossils, Trinajstic says, suggesting that the development of these organs occurred in bony fish after they diverged from placoderms.

From Scientific American

But now a startling discovery has upended the theory: researchers have found the partial skull-roof and brain case of a placoderm composed of bone.

From The Guardian

It was a modest member of the placoderm group, which included Earth's first true monster, a fish called Dunkleosteus with huge, powerful jaws that was bigger than a great white shark.

From Reuters