Lethiscus stocki (Wellstead 1982, Pardo et al. 2017; Viséan, Early Carboniferous,340 mya) was a snake-like basal tetrapod related to Ophiderpeton (below), but with larger orbits. The vertebrae retain small intercentra.

Much has been made about the age of Lethiscus, but several reptiles are just as old. Pardo et al. nested Lethicus between Acanthostega and Pederpes, but that is not supported by the present cladogram.

Ophiderpeton granulosum (Wright and Huxley 1871; Early Carboniferous–Early Permian, 345-295mya; 70cm+ length; above, dorsal view) was considered an aïstopod based on its long, snake-like, limbless torso. Here it nests with Acherontiscus apart from another aïstopod, Phlegethontia. The orbits faced laterally, but were far forward. A long lateral temporal fenestra housed large jaw muscles.

Oestocephalus amphiuminus (Cope 1868; above lateral views) is known from tiny immature and larger mature specimens.

Rileymillerus cosgriffi (Bolt and Chatterjee 2000; Late Triassic) is widely considered a tiny temnospondy related to giant, flat-headed metoposaurs and capitosaursl, but here nests with equally long, small and nearly legless Oestocephalus and Ophiderpeton (above). Distinct from related taxa, the orbits are set at mid skull. The vomer includes a long fang. The mandible is slender and curves dorsally at the tip.

Bolt JR and Chatterjee S 2000. A New Temnospondyl Amphibian from the Late Triassic of Texas. Journal of Paleontology 74(4):670-683.

Carroll RL 1967. An Adelogyrinid Lepospondyl Amphibian from the Upper Carboniferous: Canadian Journal of Zoology 45(1):1-16.

Carroll RL and Gaskill P 1978. The order Microsauria. American Philosophical Society, Philadelphia, 211 pp.

Pardo JD,Szostakiwskyj M, Ahlberg PE and Anderson JS 2017. Hidden morphological diversity among early tetrapods. Nature doi:10.1038/nature22966

Wellstead CF 1982. A Lower Carboniferous aïstopod amphibian from Scotland. Palaeontology. 25: 193–208.

Wright EPand Huxley TH 1871. On a Collection of Fossil Vertebrata, from the Jarrow Colliery, County of Kilkenny, Ireland. Transactions of the Royal Irish Academy 24:351-370

wiki/Dolichopareias
wiki/Ophiderpeton
wiki/Oestocephalus
wiki/Rileymillerus
wiki/Acherontiscus