Acleistorhinus pteroticus (Daly 1969) Early Permian, ~3.5 cm skull length was consiered by DeBraga (2001, 2003) to be a Parareptile related to Lanthanosuchus, which is a clear mismatch. Here Acleistorhinus is derived from a sister to the RC14 specimen of Milleretta, is a sister to Delorhynchus (below) and phylogenetically preceded Eunotosaurus.

Distinct from RC14, the skull of Acleistorhinus was further downturned anteriorly. The maxilla ascended to cut off the lacrimla from the naris and to contact the prefrontal. The jugal separated from the squamosal creating a lateral temporal fenestra. The supratemporal was enlarged. The second half of the skull was expanded laterally, rotating the orbits anteriorly for better binocular vision.

Since both Eunotosaurus and Milleretta had expanded ribs, it is likely that Acleistorhinus did so too.

Klastomycter conodentatus (Reisz, Rowe and Bevitt 2024, early Permian, 289 mya) is a relative of Acleistorhinus in the LRT and Delorhynchus in the original paper, which was hobbled by taxon exclusion and continued belief in the invalid clade, Parareptilia.

Delorhynchus cifelli (Reisz et al. 2014) is an Early Permian terrestrial reptile from Oklahoma. Derived from a sister to Acleistorhinus, Delorhynchus was basal to Eunotosaurus and was larger than both. The jugal had two posterior processes. The squamosal is largely unknown. No expanded ribs were found with this specimen.

Reisz et al. nested Delorhynchus with Lanthanosuchus and Acleistorhinus, but Lanthanosuchus nests with Macroleter in the large reptile tree here.

Dendromaia unamakiensis (Maddin, Mann and Hebert 2020; Late Carboniferous) was originally considered a parent of a conspecific juvenile found beneath the femur. Here the two are unrelated roommates. The large specimen nests among skull-only taxa like Acleistorhinus and Delorhynchus. The small specimen nests with the protodiapsid Heleosaurus.

Daly E 1969. A new procolophonoid reptile from the Lower Permian of Oklahoma. Journal of Paleontology 43: 676-687.

DeBraga M 2001. The postcranial anatomy of Procolophon (Parareptilia: Procolophonidae) and its implications for the origin of turtles. PhD thesis, University of Toronto.

DeBragra M 2003. The postcranial skeleton, phylogenetic position and probable lifestyle of the Early Triassic reptile Procolophon trigoniceps. Canadian Journal of Earth Sciences 40: 527-556.

DeBraga M and Reisz RR 1996. The Early Permian reptile Acleistorhinus pteroticus and its phylogenetic position. Journal of Vertebrate Paleontology 16(3): 384–395.

Maddin HC, Mann A and Hebert B 2020. Varanopid from the Carboniferous of Nova Scotia reveals evidence of parental care in amniotes. Nature ecology & evolution 4:50–56.

Reisz RR, Macdougall MJ and Modesto S 2014. A new species of the parareptile genus Delorhynchus, based on articulated skeletal remains from Richards Spur, Lower Permian of Oklahoma. Journal of Vertebrate Paleontology 34:1033–1043.

Reisz RR, Rowe DCT and Bevitt JJ 2024. Klastomycter conodentatus, gen et sp. nov., a small early Permian parareptile with conical teeth from Richards Spur, Oklahoma. PeerJ 12:e18393 http://doi.org/10.7717/peerj.18393

wiki/Acleistorhinus
wiki/Dendromaia
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wiki/Delorhynchus
wiki/Parareptilia