acanthodian /ˌæk.n̩ˈθoʊ.di.n̩/adjective 1noun 1forms 1 adjective1 •Pertaining to Acanthodii. noun1 •A member of a group of extinct fish (Acanthodii) that existed from the Silurian to the Permian period.The emerging picture of acanthodian (and perhaps placoderm) paraphyly does not overturn a general consensus about gnathostome interrelationships. — 2009 formsacanthodians
