morrowi El Adli, Deméré, and Boessenecker, 2014 Herpetocetus is a genus of cetotheriid mysticete in the subfamily Herpetocetinae.

Considerably smaller than modern baleen whales, Herpetocetus measured only 3 to 4 meters in length.

[2] Additionally, due to the structure of its jaw, it was unable to open its mouth as wide as modern baleen whales, making it incapable of lunge feeding.

[5] An additional unnamed species from Japan has been referred to the nomen dubium Mizuhoptera sendaicus in the past,[6] but the undiagnostic nature of the holotype of the latter means that it cannot be confidently referred to M.

[2] Since other cetotheriids became extinct by the end of the Neogene, it's therefore possible that some Pliocene representatives of Cetotheriidae made it into the Pleistocene to co-exist with extant mysticete species.