placoderm

noun

1. A member of an extinct paraphyletic class (†Placodermi) of jawed fish with armored heads and thoraces; the group lived during the Silurian and Devonian periods.

   “Out to sea are placoderms – heavily armoured fish, some of them more than six metres (twenty feet) long and equipped with massive, powerful jaws.”

adj

1. (not-comparable)Pertaining to the paraphyletic class †Placodermi.

   “Research published recently on placoderm fish fossils from Scottish Devonian lakes (around 365 myo) found evidence for how this extinct group of animals copulated.”