Younginidae

Younginidae; Temporal range: Late Permian, Late Permian PreꞒ Ꞓ O S D C P T J K Pg N
	Life restoration of Youngina
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Diapsida
Clade:	Neodiapsida
Family:	†Younginidae; Broom, 1914

Younginidae is an extinct family of diapsid reptiles from the Late Permian. In a phylogenetic context, younginids are near the base of the clade Neodiapsida. The only species definitively a member of the Younginidae is Youngina capensis from the Late Permian of South Africa. Several genera have historically been assigned to this family, though more recent phylogenetic analyses have supported relationships with other clades. Heleosuchus griesbachi from the Late Permian of South Africa may also be a member of the family.^[1]

Younginidae was traditionally assigned to Eosuchia, an order containing an assemblage of basal diapsids now thought to represent an evolutionary grade rather than a true clade. In 1945 paleontologist Alfred Romer reclassified Younginidae within a new group, Younginiformes, grouping it with the families Tangasauridae and Prolacertidae. Romer considered Younginidae to include many genera that are no longer classified as younginids: Paliguana, Palaegama, and Saurosternon are now considered basal lepidosauromorphs, Galesphyrus and Heleosuchus are diapsids of uncertain affinities (incertae sedis), Heleophilus is now a millerettid, and Heleosaurus is now thought to be a varanopid synapsid.^[2]^[3] Like Eosuchia, Younginiformes is no longer considered valid; for example, the phylogenetic analysis of Reisz et al. place younginids close to Sauria, the clade including the still-living archosauromorph and lepidosauromorph reptiles, while the 'younginiform' family Tangasauridae takes a more basal position in Neodiapsida.^[4] Below is a cladogram from that analysis:^[4]

Captorhinidae

	Acerosodontosaurus

	Hovasaurus

Younginidae

	Thadeosaurus

	Youngina

Claudiosaurus

Sauria

	Archosauromorpha

	Lepidosauromorpha

References

^ Buffa, Valentin; Jalil, Nour‐Eddine; Falconnet, Jocelyn; Vincent, Peggy (2025-03-23). "The neodiapsid Thadeosaurus colcanapi from the upper Permian of Madagascar". Papers in Palaeontology. 11 (2). doi:10.1002/spp2.70008. ISSN 2056-2799.
^ Laurin, M.; Reisz, R.R. (1995). "A reevaluation of early amniote phylogeny" (PDF). Zoological Journal of the Linnean Society. 113 (2): 165–223. doi:10.1111/j.1096-3642.1995.tb00932.x. Archived from the original (PDF) on 2020-04-13. Retrieved 2012-05-18.
^ Reisz, R.R.; Modesto, S.P. (2007). "Heleosaurus scholtzi from the Permian of South Africa: a varanopid synapsid, not a diapsid reptile". Journal of Vertebrate Paleontology. 27 (3): 734–739. doi:10.1671/0272-4634(2007)27[734:HSFTPO]2.0.CO;2. S2CID 86246959.
^ ^a ^b Robert R. Reisz; Sean P. Modesto; Diane M. Scott (2011). "A new Early Permian reptile and its significance in early diapsid evolution". Proceedings of the Royal Society B. 278 (1725): 3731–3737. doi:10.1098/rspb.2011.0439. PMC 3203498. PMID 21525061.

[Buffa2025-1] Buffa, Valentin; Jalil, Nour‐Eddine; Falconnet, Jocelyn; Vincent, Peggy (2025-03-23). "The neodiapsid Thadeosaurus colcanapi from the upper Permian of Madagascar". Papers in Palaeontology. 11 (2). doi:10.1002/spp2.70008. ISSN 2056-2799.

[LR95-2] Laurin, M.; Reisz, R.R. (1995). "A reevaluation of early amniote phylogeny" (PDF). Zoological Journal of the Linnean Society. 113 (2): 165–223. doi:10.1111/j.1096-3642.1995.tb00932.x. Archived from the original (PDF) on 2020-04-13. Retrieved 2012-05-18.

[RM07-3] Reisz, R.R.; Modesto, S.P. (2007). "Heleosaurus scholtzi from the Permian of South Africa: a varanopid synapsid, not a diapsid reptile". Journal of Vertebrate Paleontology. 27 (3): 734–739. doi:10.1671/0272-4634(2007)27[734:HSFTPO]2.0.CO;2. S2CID 86246959.

[reisz2011-4] Robert R. Reisz; Sean P. Modesto; Diane M. Scott (2011). "A new Early Permian reptile and its significance in early diapsid evolution". Proceedings of the Royal Society B. 278 (1725): 3731–3737. doi:10.1098/rspb.2011.0439. PMC 3203498. PMID 21525061.

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