[Neoselachii] Compagno, 1977 - modern sharks and rays see Cohort Neoselachii Compagno, 1977
   Order Hexanchiformes Compagno, 1973 - six-gill sharks
     Family Hexanchidae Gray, 1851 - cow sharks
       Genus Hexanchus Rafinesque, 1810
         1 Hexanchus griseusᵀ (Bonnaterre, 1788) - bluntnose sixgill shark
         2 Hexanchus vitulus Springer & Waller, 1969 - bigeye sixgill cowshark