After its description by Brant in 1872, Cetotheriidae was used as a
wastebasket taxon for baleen whales which were not assignable to
extant whale families. Comparing the cranial and mandibular morphology of 23 taxa (including late archaeocetes and both fossil and extant mysticetes), found Cetotheriidae in this traditional sense to be polyphyletic. Based on ten cranial characters, they also concluded that of the twelve included fossil baleen-bearing mysticetes, six formed a monophyletic group, Cetotheriidae
sensu stricto. Several phylogenetic studies since Bouetel & Muizon 2006 support the monophyly of a small group of core Cetotheriidae
sensu stricto, archaic mysticetes with a cranium that have "a long ascending process of the maxilla with anteriorly diverging lateral border that interdigitates with the frontal" and some other characters. This group is limited to
Cetotherium rathkii,
Metopocetus durinasus,
Mixocetus elysius,
Herpetocetus scaldiensis,
H. transatlanticus,
H. bramblei,
Nannocetus eremus, and
Piscobalaena nana. The remaining genera placed in the family are considered Cetotheriidae
sensu lato and are often referred to as the 'cetotheres'. found that the pygmy right whale formed a well-supported clade with Eschrichtiidae and Balaenopteridae based on molecular data, and that, within 'cetotheres', it was most closely related to the herpetocetines (
Herpetocetus and
Nannocetus) Bisconti et al. 2013, however, found, based on morphological data, it to be more closely related to
Balaenidae (the
bowhead and right whales), but added that additional specimens are expected to resolve these conflicting results within a few years. Classification of Cetotheriidae according to El Adli et al. (2014) and the Fossilworks online database: • †
Cetotherium Brandt 1843 • †
Ciuciulea Gol'din, 2018 • †
Eucetotherium Brandt 1873 • †
Vampalus • †
Zygiocetus Tarasenko 2014 • Subfamily
Herpetocetinae Steeman, 2007 • †
Herentalia Bisconti 2015 • †
Herpetocetus Van Beneden 1872 • †
Miocaperea • ?
Caperea (Gray, 1846)
Incertae sedis: • †
Hibacetus Otsuka and Ota 2008 ==References==