A review of the paleontological literature shows that the early dates of appearance of Lissamphibia recently inferred from molecular data do not favor an origin of extant amphibians from temnospondyls, contrary to recent claims. A supertree is assembled using new Mesquite modules that allow extinct taxa to be incorporated into a time-calibrated phylogeny with a user-defined geological time scale. The supertree incorporates 223 extinct species of lissamphibians and has a highly significant stratigraphic fit. Some divergences can even be dated with sufficient precision to serve as calibration points in molecular divergence date analyses. Fourteen combinations of minimal branch length settings and 10 random resolutions for each polytomy give much more recent minimal origination times of lissamphibian taxa than recent studies based on a phylogenetic analyses of molecular sequences. Attempts to replicate recent molecular date estimates show that these estimates depend strongly on the choice of calibration points, on the dating method, and on the chosen model of evolution; for instance, the estimate for the date of the origin of Lissamphibia can lie between 351 and 266 Mya. This range of values is generally compatible with our time-calibrated supertree and indicates that there is no unbridgeable gap between dates obtained using the fossil record and those using molecular evidence, contrary to previous suggestions.

The origins of the extant amphibians (frogs, salamanders, caecilians) remain controversial after over a century of debate. Three groups of hypotheses persist in the current literature: the "temnospondyl hypothesis" (TH) which roots Lissamphibia Haeckel, 1866 (the smallest clade composed of the extant amphibians) within the Paleozoic temnospondyls, the "lepospondyl hypothesis" (LH) which postulates a monophyletic Lissamphibia nested within the Paleozoic lepospondyls, and the "polyphyly hypothesis" (PH), according to which the frogs and the salamanders are temnospondyls while the caecilians are lepospondyls. The discovery of the Middle Jurassic to Pliocene albanerpetontids, which are very similar to the extant amphibians, has complicated rather than resolved this situation. We present a review of recent publications and theses in this field, several of which show more support for the LH than for the TH and considerably more than for the PH. In addition, we show that there is no particular attraction between long-bodied lissamphibians (caecilians) and long-bodied lepospondyls (such as the lysorophians): when they are removed from two published matrices, reanalyses nonetheless find the LH. In one case the LH is found even when all salamanders are removed as well. We furthermore propose that the complex of characters called the salamander mode of autopodium development is (in its less extreme forms) plesiomorphic for limbed vertebrates, so the apparent presence of this mode of development in temnospondyls cannot support the TH or the PH. Still, a consensus will not be reached soon, despite the increasing