Lupopsyrus pygmaeus is placed as the basal-most acanthodian species,Brochoadmones milesi, Euthacanthus macnicoli, and diplacanthids are relatively derived “climatiiform” fishes, andthe heavily armored condition in Climatius reticulatus and Brachyacanthus scutiger appears as a uniquely derivedstate and not primitive for all acanthodians.