Chinlestegophis, a stereospondyl temnospondyl from the Late Triassic Chinle Formation of Colorado, was proposed to be a stem-caecilian in a 2017 paper by Pardo and co-authors. If confirmed, this would bolster the proposed pre-Triassic origin of Lissamphibia suggested by molecular clocks. It would fill a gap in the fossil record of early caecilians and suggest that stereospondyls as a whole qualify as stem-group caecilians. However, affinities between Chinlestegophis and gymnophionans have been disputed along several lines of evidence. A 2020 study questioned the choice of characters supporting the relationship, and a 2019 reanalysis of the original data matrix found that other equally parsimonious positions were supported for the placement of Chinlestegophis and gymnophionans among tetrapods.
