Data from: Fossils, molecules, divergence times, and the origin of Lissamphibians

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.对古生物学文献的综述显示，近期基于分子数据推断出的滑体两栖类（Lissamphibia）早期出现时间，并不支持现生两栖类起源于离片椎类（temnospondyls），这与近期的相关研究主张相悖。本研究采用全新的Mesquite模块构建超树，该模块可将灭绝类群纳入基于用户自定义地质年代标尺校准的时间系统发育树中；该超树涵盖223种滑体两栖类灭绝物种，且具有极高显著性的地层拟合度。部分分化事件甚至可被精确定年，足以作为分子分化时间分析中的校准点。通过14组最小分支长度参数组合以及对每个多歧分支的10种随机消解方式，本研究得到的滑体两栖类群最小起源时间远晚于近期基于分子序列系统发育分析的相关研究结果。对近期分子定年估算结果的重复验证显示，这些估算结果强烈依赖于校准点的选择、定年方法以及所采用的演化模型；例如，滑体两栖类起源时间的估算值可介于351至266百万年前（Mya）之间。该数值区间总体上与本研究的时间校准超树相符，表明化石记录与分子证据得到的定年结果之间并不存在此前研究所提出的不可逾越的鸿沟。