The genus Calyptocephalella contains one living species, the helmeted water toad (C. gayi), which is very large and mostly aquatic. The genus Telmatobufo contains four species, T. australis, T. bullocki, T. ignotus, and T. venustus.[1] All five living species within the family are considered threatened, with T. bullocki and T. venustus being classified as critically endangered.[2]
The family has been present in southern South America since the Late Cretaceous[3] and were present in the Antarctic Peninsula during the Eocene.[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. Together, these groups comprise the clade Australobatrachia.[7]
^Frost, Darrel R. (2013). "Calyptocephalellidae, Reig 1960". Amphibian Species of the World 6.0, an Online Reference. American Museum of Natural History. Retrieved 19 September 2014.
^Agnolin, F. A new Calyptocephalellidae (Anura, Neobatrachia) from the Upper Cretaceous of Patagonia, Argentina, with comments on its systematic position. Stud. Geol. Salamanticensia 48, 129–178 (2012).
^Otero, R.A.; P. Jimenez-Huidobro; S. Soto-Acuña; R.E.Yury-Yáñez (2014). "Evidence of a giant helmeted frog (Australobatrachia, Calyptocephalellidae) from Eocene levels of the Magallanes Basin, southernmost Chile". Journal of South American Earth Sciences. 55: 133–140. Bibcode:2014JSAES..55..133O. doi:10.1016/j.jsames.2014.06.010.