Belongs within: Batrachosauria.
Contains: Nectridea, Albanerpetontidae, Gymnophiona, Anura, Caudata.
The Lepospondyli are a clade of amphibian-grade tetrapods known from the Lower Carboniferous to the Upper Permian though the living amphibians may also be nested here. The basal members of the clade were the lizard- or salamander-like microsaurs, all small animals with relatively short legs. The ‘microsaurs’ were paraphyletic to more derived subgroups such as the Nectridea or Lysorophia. The Lysorophia were small, serpentine animals with an extremely elongate trunk and reduced, poorly ossified limbs and girdles (Ruta et al. 2003).
The earliest clear relatives of the modern amphibians are known from the Early Triassic. Chinlestegophis jenkinsi, a probably burrowing amphibian from the Upper Triassic of Colorado, is a potential relative of caecilians, sharing with them a wide cultriform process on the skull, laterally placed eyes and double tooth rows on the mandible. The Early Jurassic Eocaecilia micropoda was even more caecilian-like as indicated by features like the loss of the tympanic ear and presence of the pseudodentary (Pardo, Small & Huttenlocker 2017). The salamanders and frogs are united in a clade Batrachia, exclusive of the caecilians, by a number of shared features such as loss of the postfrontal, surangular and splenial bones and loss of dermal scales (Frost et al. 2006). Triadobatrachus massinoti, from the early Triassic of Madagascar, was similar to a modern frog in overall appearance but retained a higher number of vertebrae, including a short tail, and was not adapted for jumping.
<==Lepospondyli [Hapsidopareiontidae, Holospondyli, Microbrachomorpha, Microsauria, Tuditanomorpha] | i. s.: Trachystegos megalodon Carroll 1966M93 |--+--Trihecaton [Trihecatontidae]DS20 | | `--T. howardinus Vaughn 1972M93 | `--+--NectrideaDS20 | `--+--MicrobrachidaeM93 | | |--Paramicrobrachis fritschi Kuhn 1959M93 | | `--Microbrachis Fritsch 1876DS20, D07 | | |--M. obtusatumD07 | | `--M. pelikani Fritsch 1876RCQ03 | `--Hyloplesion [Hyloplesiontidae]DS20 | `--H. longicostatum Fritsch 1876RCQ03 `--+--+--PantylidaeRCQ03 | | |--Pantylus cordatus Cope 1871DS20, RCQ03 | | `--Stegotretus agyrus Berman, Eberth & Brinkman 1988AR08, RCQ03 | `--TuditanidaeRCQ03 | | i. s.: Boii crassidens (Fritsch 1876)M93 | |--Asaphestera intermedia (Dawson 1894)DS20, RCQ03 | `--+--CrinodonDS20 | `--Tuditanus punctulatus Cope 1874DS20, RCQ03 `--+--Saxonerpeton geinitzi (Credner 1890)AR08, RCQ03 `--+--+--+--Rhynchonkos [Goniorhynchidae, Rhynchonkidae]DS20 | | | `--R. stovalli (Olson 1970)RCQ03 | | `--+--Dvellecanus carrolliPS17 | | `--Aletrimyti gaskillaePS17 | `--+--+--Huskerpeton englehorniPS17 | | `--GymnarthridaePS17 | | |--Hylerpeton dawsoniT85 | | |--Leiocephalikon problematicumC00, T85 | | |--Elfridia Thayer 1985T85 | | | `--*E. bulbidens Thayer 1985T85 | | |--EuryodusDS20 | | | |--E. dalyaeAR08 | | | `--E. primus Olson 1939RCQ03 | | `--CardiocephalusDS20 | | |--C. dalyaeC00 | | |--C. peabodyiAR08 | | `--C. sternbergi Broili 1904RCQ03 | `--+--Nannaroter mckinzeiPS17 | `--OstodolepidaePS17 | |--Micraroter erythrogeios Daly 1973DS20, RCQ03 | |--Pelodosotis elongatum Carroll & Gaskill 1978DS20, RCQ03 | `--Ostodolepis brevispinatus Williston 1913M93 `--+--+--Odonterpeton [Odonterpetontidae]DS20 | | `--O. triangulare Moodie 1909RCQ03 | `--Sparodus Fritsch 1876DS20, RCQ03 | `--S. validensRCQ03 `--+--+--Hapsidopareion lepton Daly 1973DS20, RCQ03 | `--Llistrofus Carroll & Gaskill 1978DS20, RCQ03 | `--L. pricei Carroll & Gaskill 1978M93 `--+--BrachystelechidaePS17 | |--Batropetes fritschia (Geinitz & Deichmüller 1882)DS20, RCQ03 | `--+--Carrolla Langston & Olson 1986RCQ03 | | `--C. craddockiRCQ03 | `--Quasicaecilia Carroll 1990RCQ03 | `--Q. texana Carroll 1990M93 `--+--LysorophiaRCQ03 | |--MolgophidaeG88 | | |--MolgophisG88 | | `--MegamolgophisG88 | `--Cocytinidae [Lysorophidae]AR08 | |--CocytinusG88 | |--Lysorophus tricarinatusC07 | |--Pleuroptyx clavatusC00 | `--BrachydectesDS20 | |--B. elongatus Wellstead 1991RCQ03 | `--B. newberryi Cope 1868RCQ03 `--+--AlbanerpetontidaeDS20 `--+--+--Rileymillerus cosgriffiPSH17 | `--+--Chinlestegophis Pardo, Small & Huttenlocker 2017PSH17 | | `--*C. jenkinsi Pardo, Small & Huttenlocker 2017PSH17 | `--Parabatrachia [Apoda]FG06 | |--Eocaecilia micropodia Jenkins & Walsh 1993PS17, RCQ03 | `--GymnophionaDS20 `--BatrachiaFB17 |--SalientiaRCQ03 | | i. s.: Czatkobatrachus polonicusRR00 | |--AnuraPSH17 | |--Prosalirus [Prosaliridae]C01 | | `--P. bitis Shubin & Jenkins 1995R00 | `--Triadobatrachus Kuhn 1962AR08, RR00 (see below for synonymy) | `--T. massinoti (Piveteau 1936)RCQ03 |--PangerpetonDS20 |--CaudataDS20 `--+--BelyanerpetonDS20 `--KarauridaeM00 |--Karaurus sharovi Ivakhnenko 1978DS20, RCQ03 `--Kokartus honorariusM00
Triadobatrachus Kuhn 1962AR08, RR00 [=Protobatrachus Piveteau 1936 (preoc.)RR00; Proanura, Triadobatrachidae]
*Type species of generic name indicated
References
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[PSH17] Pardo, J. D., B. J. Small & A. K. Huttenlocker. 2017. Stem caecilian from the Triassic of Colorado sheds light on the origins of Lissamphibia. Proceedings of the National Academy of Sciences of the USA 114 (27): E5389–E5395.
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[RCQ03] Ruta, M., M. I. Coates & D. L. J. Quicke. 2003. Early tetrapod relationships revisited. Biological Reviews 78: 251–345.
[T85] Thayer, D. W. 1985. New Pennsylvanian lepospondyl amphibians from the Swisshelm Mountains, Arizona. Journal of Paleontology 59 (3): 684–700.