Rhinesuchus whaitsi, BROOM, 1908

Marsicano, Claudia A., Latimer, Elizabeth, Rubidge, Bruce & Smith, Roger M. H., 2017, The Rhinesuchidae and early history of the Stereospondyli (Amphibia: Temnospondyli) at the end of the Palaeozoic, Zoological Journal of the Linnean Society 181, pp. 357-384 : 360-361

RHINESUCHUS WHAITSI BROOM, 1908

R. whaitsi Broom, 1908: 373 , original description.

R. broomianus von Huene, 1931: 4 (synonymized herein).

R. beaufortensis Boonstra, 1940: 197 [(synonymized by Schoch & Milner (2000: 72)].

Muchocephalus muchos Watson, 1962: 229 (synonymized herein).

Holotype: SAM-PK-1212 comprises a basicranium ( Fig. 1A–F ), seven fragments of the middle portion of the left hemimandible, 11 skull fragments including part of the left anterolateral side of the skull (putative fragments of the maxilla, palatine and ectopterygoid and jugal) and some pieces of the posterior right side of the skull (quadratojugal, quadrate ramus of the pterygoid and quadrate).

Type locality and horizon: Leeu-Gamka (‘Fraserburg Road Station’), Prince Albert District (Western Cape Province, South Africa); Tapinocephalus Assemblage Zone, Guadalupian ( Rubidge et al., 2013) .

Referred specimens: A portion of a palate from Zeekoegat, Prince Albert District (Western Cape Province) mentioned by Broom (1908: 373) without any reference to a collection, and currently lost. SAM-PK-3009 ( Figs 2A–D , 3A–D ), a nearly complete skull and mandibles (left hemimandible and three fragments of the right hemimandible) from an unknown locality near Beaufort West and considered to be from the ‘ Endothiodon zone’ according to Haughton (1915: 67). A specimen listed by Haughton (1925) as the posterior half of a skull from the ‘ Tapinocephalus beds’ of Blaauw Krantz (Prince Albert District, Western Cape Province), housed in the collections of the South African Museum, but without any reference to a collection number ( Haughton, 1925: 228). SAM-PK-9135, a poorly preserved skull in six pieces, which includes the right margin of the skull and the posterior part of the palate (basicranial region), and part of the medium third of the left hemimandible, from the Prince Albert District (Farm Vogelfontein, Western Cape Province), Tapinocephalus Assemblage Zone ( Watson, 1962: 226) . UMZC T. 64 (= DMSW B. 118) a partial basicranium collected on the farm Zeekoegat, Prince Albert District (Western Cape Province, South Africa), Tapinocephalus Assemblage Zone ( Watson, 1962: 226) .

Remarks: In 1905 Broom discovered a small unidentifiable portion of an amphibian palate covered with a shagreen of teeth at Zeekoegat, Prince Albert District ( Broom, 1908: 373). Two years later, a second fragmentary skull (SAM-PK-1212) of a ‘new Labyrinthodont’ was exhumed near ‘Fraserburg Road Station’ (now Leeuw-Gamka), and together the specimen from Zeekoegat, Broom erected the new taxon, R. whaitsi ( Broom, 1908: 373) . Haughton (1915) revised Broom’s Rhinesuchus species and referred SAM-PK-3009 to R. whaitsi , but wrongly designated it as the paratype of R. whaitsi ( Haughton, 1925: 229) . Watson (1919: 11, fig. 3) reported that Broom had re-examined the R. whaitsi material and sent him a figure of the palate from which it was apparent that it was SAM-PK-3009. In 1925, Haughton mentioned a specimen comprising the posterior half of the skull ‘encrusted with a thin layer of matrix’, from the ‘ Tapinocephalus zone beds’ of BlaauwKrantz, as R. whaitsi . He made no reference to the specimen number, only that it was housed in the South African Museum ( Haughton, 1925: 228). Boonstra (1940) re-studied SAM-PK-3009 and erected the new species R. beaufortensis , based on the differences in skull size and proportions with the holotype of R. whaitsi ( Boonstra, 1940: 197) . Watson (1962) assigned to R. whaitsi two additional specimens from the Prince Albert District, ‘the posterior end of a lower jaw’ ( SAM-PK 9135) from Vogelfontein and a specimen ( UMZC T. 64 = DMSW B. 118) from Zeekoegat that consisted of a partial basicranial region ( Watson, 1962: 226). Specimen SAM-PK 9135 includes several fragments of the posterior half of a skull plus a partial mandible encrusted in a thin layer of a crystallized mineral, all of the same individual. It is very probable that the posterior half of the skull of SAM-PK 9135 represents the same skull fragment referred by Haughton in 1925 as R. whaitsi (see ‘ Rhinesuchus whaitsi Broom, 1908 ’ section), although he mentioned that it was collected on farm Blaauw Krantz, also in Prince Albert District.

Figures

Figure 1. SAM-PK-1212, skull holotype of Rhinesuchus whaitsi. (A, B) Dorsal view. (C, D) Ventral view. (E, F) Occipital view. Scale bar equals 5 cm.Anatomical abbreviations: a, angular; amf, anterior meckelian foramen; ar, articular; bo, basioccipital; ctf, chordatympanic foramen; d, dentary; eo, exoccipital; f, frontal; j, jugal; l, lacrimal; la, lamella; mb, ‘membrane’; mx, maxilla; n, nasal; or, oblique ridge, p, parietal; pa, palatine; par, prearticular; prf, prefrontal; pmf, posterior meckelian foramen; pmx, premaxilla; po, postorbital; pf, postfrontal; pp, postparietal; ps, parasphenoid; psp, postsplenial; pt, pterygoid; q, quadrate; qj, quadratojugal; s, stapes; san, surangular; sg, stapedial groove; smx, septomaxilla; sp, splenial; spet, sphenetmoid; sq, squamosal; st, supratemporal; t, tabular; v, vomer.

Figure 2. SAM-PK-3009, skull holotype of ‘Rhinesuchus beaufortensis’. (A, B) Dorsal view. (C, D) Ventral view. Scale bar equals 5 cm.

Figure 3. SAM-PK-3009, mandible holotype of ‘Rhinesuchus beaufortensis’. (A, B) Labial view. (C, D) Lingual view. Scale bar equals 5 cm.