Galesphyrus

Not to be confused with Galechirus.

Galesphyrus Temporal range: mid–late Permian, ~Capitanian–Changhsingian PreꞒ Ꞓ O S D C P T J K Pg N
Holotype specimen of G. capensis
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Neodiapsida
Family:	†Younginidae
Genus:	†Galesphyrus Broom, 1914
Species:	†G. capensis
Binomial name
†Galesphyrus capensis Broom, 1914

Galesphyrus is an extinct genus of early diapsid reptile known from the Permian of South Africa. The taxonomic, geographic, and geological histories of Galesphyrus are complex, and little research has been conducted on it. When described in 1914, it was identified as therapsid, more closely related to mammals than reptiles. However, later researchers agreed that Galesphyrus is a reptile, possibly related to neodiapsids like Youngina. The genus contains a single species, Galesphyrus capensis, known from a single specimen, although a second specimen has historically been referred to it. Both specimens preserve the natural moulds of partial articulated skeletons.

History

Robert Broom first described Galesphyrus capensis in 1914 based on SAM-PK-2758, a natural mould of a partial articulated skeleton. He identified it as a probable 'dromasaurian' member of the Therapsida—the broader clade containing mammals.^[1] About ten years later, he revised this classification after noticing reptilian features of the foot, preferring an 'eosuchian' identity.^[2] In 1976, Robert L. Carroll redescribed the taxon as a member of the Younginidae, also referring BP/1/4286, an additional mold of a partial skeleton with a fragmentary skull, to it.^[3] Discussing the relationships of early reptiles in 1985, Michael J. Benton identified characters supporting Galesphyrus in an indeterminate position within Neodiapsida but outside of the reptile crown group.^[4]

In 2025 Valentin Buffa and colleagues published a thorough redescription of Galesphyrus, determining it likely belongs to the clade Parapleurota, outside of Neodiapsida. They further noted anatomical differences between BP/1/4286 and the holotype, thus restricting Galesphyrus to the holotype, SAM-PK-2758.^[5]

The Galesphyrus holotype likely derives from Oorlogs Poort 85 Farm, a locality in Joe Gqabi District Municipality of Eastern Cape Province in South Africa, although the exact discovery location was not documented carefully and is now unknown. Outcrops near Oorlogs Poort 85 Farm belong to a range of biozones, spanning the Endothiodon, Cistecephalus, and Daptocephalus assemblage zones, with the Tapinocephalus Assemblage Zone being exposed nearby. As such, the temporal range of Galesphyrus can only be restricted to the late Capitanian through early Changhsingian ages of the middle to upper Permian period.^[5]

Classification

Illustrated hindlimb of Galesphyrus (C) compared to the fore- and hindlimbs of the therapsid Galechirus (A, B) and millerettid reptile Broomia (E, D)

In their 2025 redescription of Galesphyrus (SAM-PK-2758) and the referred specimen BP/1/4286, Buffa, Jenkins, and Benoit performed a series of phylogenetic analyses to determine the relationships and affinities of these specimens. Using an updated and expanded version of the phylogenetic matrix published by Buffa and colleagues in their 2025 redescription of Thadeosaurus,^[6] the researchers performed a series of three unconstrained maximum parsimony analyses, removing fragmentary operational taxonomic units (OTUs) each time to improve resolution and better observe the position of Galesphyrus. In the third analysis, after trimming BP/1/4286 (only a fragmentary postcranium) and Lanthanolania (only a skull), Galesphyrus was recovered as a member of the researchers' "Clade P", generally equivalent to the Parapleurota of Jenkins and colleagues (2025),^[7] as the sister taxon to the clade formed by Millerettidae and Neodiapsida. These results are displayed in the cladogram below, which highlights taxa traditionally recovered within a monophyletic Parareptilia. The likely position of Lanthanolania is shown, inferred from the first analysis iteration.^[5] ⊞ buttons can be clicked to expand nodes.

Diapsida

Araeoscelidia ⊞ Araeoscelis spp. Petrolacosaurus kansensis ⊟ Bolosauridae ⊞ Bolosaurus major Eudibamus cursoris ⊟ Australothyris smithi Acleistorhinidae ⊞ Delorhynchus cifellii Feeserpeton oklahomensis ⊟ Varanopidae ⊞ Orovenator mayorum Archaeovenator hamiltonensis Heleosaurus scholtzi Mesenosaurus romeri Mycterosaurus longiceps Aerosaurus wellesi Varanops brevirostris ⊟ Neoreptilia Mesosaurus tenuidens Procolophonia ⊞ Pareiasauromorpha Deltavjatia rossicus Emeroleter levis Macroleter poezicus Procolophonoidea Procolophon trigoniceps Barasaurus besairiei Saurodektes kitchingorum ⊟ 'Clade P' Lanthanolania ivakhnenkoi Galesphyrus capensis    Millerettidae ⊞ Broomia perplexa Milleretta rubidgei Milleropsis pricei ⊟ Neodiapsida Younginidae ⊞ Youngina Akkedops bremneri SAM-PK-K7710 ⊟ Tangasauridae ⊞ Kenyasaurus mariakaniensis Acerosodontosaurus piveteaui Thadeosaurus colcanapi Hovasaurus boulei Tangasaurus mennelli ⊟ Claudiosaurus germaini Weigeltisauridae ⊞ Coelurosauravus elivensis Rautiania spp. Weigeltisaurus jaekeli ⊟ Sauria Archosauromorpha Lepidosauromorpha (≈Parapleurota)

   former 'parareptiles'

References

1. Broom, Robert (1914-10-31). "I. Croonian Lecture: On the origin of mammals". Philosophical Transactions of the Royal Society of London, Series B. 206 (325–334): 1–48. doi:10.1098/rstb.1915.0001. ISSN 0264-3960.
2. Broom, Robert (1924). "Further evidence on the structure of the Eosuchia". Bulletin of the American Museum of Natural History. 51 (3): 67–76.
3. Carroll, Robert L. (1976). "Galesphyrus capensis, a younginid eosuchian from the Cistecephalus Zone of South Africa". Annals of the South African Museum. 72 (4): 59–68.
4. Benton, Michael J. (1985-06-28). "Classification and phylogeny of the diapsid reptiles". Zoological Journal of the Linnean Society. 84 (2): 97–164. doi:10.1111/j.1096-3642.1985.tb01796.x.
5. Buffa, Valentin; Jenkins, Xavier A.; Benoit, Julien (2025-11-17). "Galesphyrus capensis from the Permian of South Africa and the origin of Neodiapsida". Journal of Systematic Palaeontology. 23 (1) 2563582. doi:10.1080/14772019.2025.2563582. ISSN 1477-2019.
6. 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) e70008. Bibcode:2025PPal...11E0008B. doi:10.1002/spp2.70008. ISSN 2056-2799.
7. Jenkins, Xavier A; Benson, Roger BJ; Ford, David P; Browning, Claire; Fernandez, Vincent; Dollman, Kathleen; Gomes, Timothy; Griffiths, Elizabeth; Choiniere, Jonah N; Peecook, Brandon R (2025-08-28). "Evolutionary assembly of crown reptile anatomy clarified by late Paleozoic relatives of Neodiapsida". Peer Community Journal. 5 e89. doi:10.24072/pcjournal.620. ISSN 2804-3871.