Phonodus dutoitorum (Modesto et al. 2010) early Triassic, skull length ~2cm, was originally described as a sister to Procolophon. In the large reptile tree Phonodus is a late surviving, but still basal bolosaurid, a clade that now nests within the diadectids, like Diadectes. Phonodus was a late survivor of a Late Pennsylvanian radiation with derived sisters like Bolosaurus and Belebey in the Early and Late Permian.

Diadectes sp. (Berman Sumida and Lombard 1992; specimen CM 25741) is closely related to Phonodus in the LRT.

Berman DS, Sumida SS and Lombard RE 1992. Reinterpretation of the Temporal and Occipital Regions in Diadectes and the Relationships of Diadectomorphs. Journal of Paleontology, Vol. 66, No. 3 (May, 1992), pp. 481-49.

Modesto SP, Scott DM, Botha-Brink J and Reisz RR 2010. A new and unusual procolophonid parareptile from the Lower Triassic Katberg Formation of South Africa. Journal of Vertebrate Paleontology 30 (3): 715–723. doi:10.1080/02724631003758003.

Rieppel OC and Zanon RT 1997. The interrelationships of Placodontia. Historical Biology: Vol. 12, pp. 211-227

wiki/Phonodus