The taxonomic status of Parathrinaxodon proops (Therapsida: Cynodontia), with comments on the morphology of the palate in basal cynodonts

Show simple item record Abdala, Fernando Allinson, Matthew 2014-12-14T11:12:20Z 2014-12-14T11:12:20Z 2005
dc.description.abstract The holotype and only specimen of Parathrinaxodon proops, a cynodont from the Upper Permian Kawinga Formation, Tanzania, is redescribed. Upper postcanines from the middle of the tooth row are ovoid in outline, presenting a large main cusp and tiny anterior and posterior accessory cusps on the sectorial margin. Anterior and posterior lingual cusps on the crown indicate the presence of a lingual cingulum. The overall postcanine morphology is remarkably similar to that of Procynosuchus delaharpeae, a Late Permian cynodont particularly common in the lower Beaufort Group of South Africa. The presence of a complete osseous palate and a medial palatal opening between the maxillae (=vomerine fossa) in Parathrinaxodon proops remain the main differences previously reported between this species and Procynosuchus delaharpeae. Restudy of the palate of Parathrinaxodon proops indicates that there exists some degree of deformation, particularly notable in the broken and distorted vomer. The supposed presence of the complete secondary palate and of the medial palatal opening in Parathrinaxodon proops are interpreted as resulting from a slight horizontal displacement of the long, and originally free, palatal processes of the maxilla and palatine. It is concluded that Parathrinaxodon proops is synonymous with Procynosuchus delaharpeae. This synonymy is problematic because Parathrinaxodon proops Parrington 1936 would have priority over Procynosuchus delaharpeae Broom 1937, but the latter is the best known Late Permian cynodont. Consequently, we propose to conserve Procynosuchus delaharpeae as the valid name for this cynodont based on article 23, section 9 (Reversal of precedence) of the International Code of Zoological Nomenclature. An analysis of the Kawinga fauna, using genus as the taxonomic unit for comparison, indicates strong similarity (67%) with faunas from theTropidostoma, Cistecephalus and Dicynodon assemblage zones from the SouthAfrican Karoo. en_ZA
dc.description.sponsorship Financial support was provided by the University of the Witwatersrand through a Postdoctoral Research Fellowship awarded to FA. The Royal Society of London and PAST (Palaeontology Scientific Trust, Johannesburg) provided FAgrants that enabled a research visit to the United Kingdom. en_ZA
dc.language.iso en en_ZA
dc.title The taxonomic status of Parathrinaxodon proops (Therapsida: Cynodontia), with comments on the morphology of the palate in basal cynodonts en_ZA
dc.type Article en_ZA

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