placoderm adjective 1noun 1forms 1 adjective1 •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. — 2018 noun1 •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. — 2012 formsplacoderms
