placoderm

American  

[plak-uh-durm] / ˈplæk əˌdɜrm /

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.

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placoderm British  

/ 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

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placoderm Scientific  

/ 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.

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Etymology

Origin of placoderm

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

Example Sentences

The fossil the team looked at is a placoderm, of the species Kolymaspis sibirica, which lived around 407 million years ago and was among earliest jaw-bearing fishes.

From Science Daily • Nov. 1, 2023

Pondering this while walking his dog, Brazeau considered CT scans of the braincase of a placoderm called Kolymaspis sibirica, collected more than 60 years ago in Siberia.

From Science Magazine • Nov. 1, 2023

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

From Salon • Oct. 1, 2022

Most are of a flat, armored placoderm species named Xiushanosteus mirabilis, which most likely lived on the seafloor.

From New York Times • Sep. 28, 2022

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 • Sep. 15, 2022