crossopterygii crossopterygian • Crossopterygii · · · Info · Definitions · Characters · · crossopterygii · · Text Latin · · Script 14 · · Length 6 · · Syllables Definitions · · · (noun) fishes having paired fins resembling limbs and regarded as ancestral to amphibians. Synonyms: Crossopterygii, subclass Crossopterygii. · · Noun Definition 1 Characters · · c latin small letter c U+0063 e latin small letter e U+0065 g latin small letter g U+0067 i latin small letter i U+0069 o latin small letter o U+006F p latin small letter p U+0070 r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074 y latin small letter y U+0079