15 letters · 23 points in Scrabble
noun any fish of the order Crossopterygii; most known only in fossil form
originFrom Crossopterygia + -an, Greek krossoí “tassels, fringe” + -o- + pterýgion “little wing or fin,” equivalent to pteryg- (stem of pterýx) “wing, fin” + -ion + -an.
Etymology from Wiktionary, CC BY-SA 3.0