Data from: The putative lissamphibian stem-group: phylogeny and evolution of the dissorophoid temnospondyls

Dissorophoid temnospondyls are widely considered to have given rise to some or all modern amphibians (Lissamphibia), but their ingroup relationships still bear major unresolved questions. An inclusive phylogenetic analysis of dissorophoids gives new insights into the large-scale topology of relationships. Based on a TNT 1.5 analysis (33 taxa, 108 characters), the enigmatic taxon Perryella is found to nest just outside Dissorophoidea (phylogenetic defintion) but shares a range of synapomorphies with this clade. The dissorophoids proper are found to encompass a first dichotomy between the largely paedomorphic Micromelerpetidae and all other taxa (Xerodromes). Within the latter, there is a basal dichotomy between the large, heavily ossified Olsoniformes (Dissorophidae + Trematopidae) and the small salamander-like Amphibamiformes (new taxon), which include four clades: (1) Micropholidae (Tersomius, Pasawioops, Micropholis), (2) Amphibamidae sensu stricto (Doleserpeton, Amphibamus), Branchiosauridae (Branchiosaurus, Apateon, Leptorophus, Schoenfelderpeton) and (4) Lissamphibia. The genera Platyrhinops and Eoscopus are here found to nest at the base of Amphibamiformes. Represented by their basalmost stem-taxa (Triadobatrachus, Karaurus, Eocaecilia), lissamphibians nest with Gerobatrachus rather than Amphibamidae as repeatedly found by former analyses.

碟形类离片椎类（Dissorophoid temnospondyls）普遍被认为演化出了部分或全部现代滑体两栖类（Lissamphibia），但其类群内部的亲缘关系仍存在诸多尚未解决的重大问题。针对碟形类的全覆盖系统发育分析（phylogenetic analysis），为其亲缘关系的宏观拓扑结构提供了全新认知。基于TNT 1.5软件开展的系统发育分析（涵盖33个分类单元、108个形态性状）显示，谜样分类单元佩里螈（Perryella）恰好嵌套于碟形亚目（Dissorophoidea，系统发育定义）的外侧类群，却与该演化支（clade）共享一系列共有衍征（synapomorphies）。狭义碟形类群存在首次二分分支：一类是以幼态持续为主要特征的细螈科（Micromelerpetidae），其余类群则归为旱螈类（Xerodromes）。在旱螈类内部，又存在一处基部二分分支：分别为体型庞大、骨化程度极高的奥尔森类群（Olsoniformes，包含碟螈科Dissorophidae + 穿孔螈科Trematopidae），以及小型蝾螈状的两栖形类（Amphibamiformes，新建演化支）。该类群包含四个演化支：（1）微螈科（Micropholidae，含特尔森螈Tersomius、帕萨维奥螈Pasawioops、微螈Micropholis）；（2）狭义两栖螈科（Amphibamidae sensu stricto，含多勒塞螈Doleserpeton、两栖螈Amphibamus）；（3）枝螈科（Branchiosauridae，含枝螈Branchiosaurus、阿帕顿螈Apateon、细螈Leptorophus、申费尔德螈Schoenfelderpeton）；（4）滑体亚纲（Lissamphibia）。本次研究发现，扁鼻螈（Platyrhinops）与始吻螈（Eoscopus）位于两栖形类的基部位置。以最基干茎类群（stem-taxa，包括三叠蛙Triadobatrachus、卡拉乌拉螈Karaurus、始蚓螈Eocaecilia）为代表的滑体两栖类，与格里蟾螈（Gerobatrachus）聚类为一支，而非如既往多项分析那般与两栖螈科聚为一支。