Amphibamidae contains the genusGerobatrachus, which has been interpreted as the sister taxon of Batrachia, the modern amphibians. This would make Amphibamidae a paraphyletic taxon, since it would not contain all descendants of the last common ancestor of amphibamids. If Gerobatrachus is the sister taxon of Batrachia, then all modern amphibians descend from an amphibamid ancestor. Below is a modified cladogram from Anderson et al. (2008) showing Batrachia nested in Amphibamidae, with Gerobatrachus as the sister taxon of Batrachia:
The cladistic analysis of Anderson et al. (2008) supported the "polyphyly hypothesis" of modern amphibian ancestry, whereby some extant amphibian groups are descendants of temnospondyls while others are descendants of lepospondyls, another large group of Paleozoic amphibians.Caecilians were nested within Lepospondyli, making Lissamphibia polyphyletic. However, the placement of Batrachia within Amphibamidae has been controversial, and alternate hypotheses of lissamphibian ancestry remain. Some authors of more recent studies have suggested that the findings of Anderson et al. (2008) may be wrong, and that lissamphibians are descendants of lepospondyls. This would make Amphibamidae a monophyletic grouping much more distantly related to lissamphibians.
^Huttenlocker, A.K.; Pardo, J.D.; Small, B.J. (2007). "Plemmyradytes shintoni, gen. et. sp. nov., an Early Permian Amphibamid (Temnospondyli:Dissorophoidea) from the Eskridge Formation, Nebraska". Journal of Vertebrate Paleontology27 (2): 316–328. doi:10.1671/0272-4634(2007)27[316:PSGESN]2.0.CO;2.
^Fröbisch, N.B.; Reisz, R.R. (2008). "A new Lower Permian amphibamid (Dissorophoidea, Temnospondyli) from the fissure fill deposits near Richards Spur, Oklahoma". Journal of Vertebrate Paleontology28 (4): 1015–1030. doi:10.1671/0272-4634-28.4.1015.