Recumbirostra is a clade of tetrapods which lived during the Carboniferous and Permian periods. They are thought to have had a fossorial (burrowing) lifestyle and the group includes both short-bodied and long-bodied snake-like forms. At least one species, the long-bodied molgophid Nagini mazonense, lost its forelimbs entirely. Recumbirostra includes the families Brachystelechidae, Gymnarthridae, Molgophidae, Ostodolepidae, Pantylidae, and Rhynchonkidae. Brachystelechids and molgophids have been grouped in the suggested clade Chthonosauria,Osteology and phylogenetic position of the diminutive 'microsaur' Odonterpeton triangulare from the Pennsylvanian of Linton, Ohio, and major features of recumbirostran phylogeny while gymnarthrids, rhynchonkids, and ostodolepidids have been grouped in the clade Nastrondormes.
Recumbirostra was erected as a clade in 2007 to include many of the taxa traditionally grouped in "Microsauria", which has since been shown to be a paraphyletic or polyphyletic grouping.Huttenlocker, A. K.; Pardo, J. D.; Small, B. J.; Anderson, J. S. (2013). "Cranial morphology of recumbirostrans (Lepospondyli) from the Permian of Kansas and Nebraska, and early morphological evolution inferred by micro-computed tomography". Journal of Vertebrate Paleontology 33 (3): 540. Like other "microsaurs", the recumbirostrans have traditionally been considered to be members of the subclass Lepospondyli; however, many phylogenetic analyses conducted since the 2010s have recovered recumbirostrans as basal sauropsid (reptilian) amniotes instead. However, the placement of recumbirostrans as reptiles has been challenged by other authors, who have recovered them as stem-amniotes instead, and contended that the shared characters between recumbirostrans and reptiles are convergent, or the result of incorrect character encoding. Not all phylogenetic analyses recognize Recumbirostra as a valid grouping. An alternative clade called Tuditanomorpha is occasionally supported and includes many of the same taxa. Furthermore, the taxa that are often considered to be recumbirostrans have been found among amphibians (and not as a distinct clade) in some analyses.
Classification
Taxonomy Altenglanerpeton Sparodus Steenerpeton? Trihecaton? Hapsidopareiidae Pantylidae Odonterpetidae Odonterpeton Joermungandr Chthonosauria Brachystelechidae Lysorophia? Nastrondormes Gymnarthridae Rhynchonkidae Aletrimyti Dvellecanus Rhynchonkos Ostodolepidae
Phylogeny The cladogram below shows the phylogenetic relationships of recumbirostrans following the results of Mann et al. (2026), which used the 2025 dataset of Jenkins et al. (the most comprehensive available matrix at the time of publication). Clade terminology is added using the latter study:
Gallery
References