The Order Temnospondyli (excluding the baphetids and colosteids) can be readily defined as a group of monophyletic origin, although it is, surely paraphyletic with respect to the extant amphibians and therefore becomes a series of plesions forming the stem-group of the Lissamphibia. The Temnospondyli is a neglected group. The family-level classification of temnospondyls has remained relatively stable and in the work presented here, we have been able to retain most previously used family units as valid clades with only the occasional need to 'split' or 'lump'. In constructing a hierarchical classification of temnospondyls, we have had to introduce a few new taxonomic units above family level, quite different from those in previous classifications. Because the systematic sections necessarily cover 160 genera and more than 300 species, we have kept the general osteological sections compact in the interest of saving space.
Most of the families and genera reviewed here are diagnosed on the basis of cranial characters. We have attempted to include all named genera and species in the synonymies but have not listed erroneous spellings. Where there are clear comparative diagnoses of two or more species within a genus, these diagnoses have been included. We regard the taxonomic sections as the most important parts of this handbook, but nevertheless have put much effort on both morphology and phylogeny, which had long been neglected in major stereospondyl groups. The cladograms we present at the end of each section are provided to make the systematic relationships clearer.