After McKenna & Bell, 1997

<==o †Cetotheriidae
   |-- †Cetotheriopsis lintianus
   |-- †Mauicetus
   |-- †Cophocetus oregonensis Packard & Kellogg, 1934
   |-- †Cetotherium
   |-- †Pelocetus calvertensis
   |-- †Aglaocetus
   |-- †Diorocetus
   |-- †Pinocetus
   |-- †Tiphyocetus
   |-- †Metopocetus
   |-- †Imerocetus
   |-- †Mesocetus
   |-- †Herpetocetus
   |-- †Isocetus
   |-- †Peripolocetus
   |-- †Halicetus
   |-- †Eucetotherium
   |-- †Cetotheriomorphus
   |-- †Parietobalaena
   |-- †Thinocetus
   |-- †Otradnocetus
   |-- †Heterocetus
   |-- †Nannocetus
   |-- †Mixocetus
   |-- †Amphicetus
   |-- †Cephalotropis
   |-- †Piscocetus
   |-- †Rhegnopsis
   |-- †Piscobalaena
   `?- †Nanisocetus

Reference(s):