. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. Fig. 9. Eodicynodon oosthuizeni, stereoview. Paired vomers reflect the primitive tetrapod condition, being present not only in sphenacodont pelycosaurs but also in the captorhinomorph cotylosaurs. The paired condition has also been recorded for the Russian Zone II form Venyukovia (Efremov 1940) which according to Watson (1948) occupies a position between the Dinocephalia, which similarly retain paired vomers, and Dicynodontia, in which the vomers have become fused. It is of interest to note that the
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. Fig. 9. Eodicynodon oosthuizeni, stereoview. Paired vomers reflect the primitive tetrapod condition, being present not only in sphenacodont pelycosaurs but also in the captorhinomorph cotylosaurs. The paired condition has also been recorded for the Russian Zone II form Venyukovia (Efremov 1940) which according to Watson (1948) occupies a position between the Dinocephalia, which similarly retain paired vomers, and Dicynodontia, in which the vomers have become fused. It is of interest to note that the vomers have become secondarily fused in only two of the main groups of the Therapsida, viz. the Dicynodontia and Gorgonopsia. The palatine is developed along two planes; a rugose ventral, compara- tively broad kidney-shaped section extending along the general palatal line from just behind the canine tusk to a tapering point in line with the anterior limit of the inter-pterygoidal vacuity, and a dorso-medially curving section which meets the dorso-lateral flange of the vomer to form the lateral and dorsal walls of the internal nares (Fig. 8). Postero-medially the palatine meets the pterygoid in a long suture. The ectopterygoid forms part of the outer edge of the palate and is wedged between the pterygoid, palatine and maxillary. Its ventral surface is as rugose as that of the palatine, from which it is separated by a deep longitudinal groove. The rugosity of the ventral surfaces of the ectopterygoid and palatine could possibly be related to the clusters of small teeth on corresponding areas on the palatine, pterygoid and ectopterygoid in pelycosaurs such as Dimetrodon and Edaphosaurus. In Eodicynodon, the antero-ventral portion of the vomer is similarly covered with small ring-like protuberances resembling the small vomerine teeth in Edaphosaurus. In most gorgonopsians sparse clusters of small teeth occur on the palatine and pterygoid. The pterygoid has 3 main processes extendin
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
