The genus Calyptocephalella contains one living species, the helmeted water toad (C. gayi), which is very large and mostly aquatic.

[1] All five living species within the family are considered threatened, with T. bullocki and T. venustus being classified as critically endangered.

[4] While originally widespread in Patagonia east of the Andes, they later became extinct in this region after the Late Miocene, likely due to increasingly cold and arid conditions.

[5] A particularly large indeterminate fossil species is known from the Eocene of southern Chile.

[6] They are the sister group to the superfamily Myobatrachoidea, which inhabits Australasia; the ancestors of Myobatrachoidea likely diverged from Calyptocephalellidae in South America, but migrated south to Australasia via then ice-free Antarctica.