. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. QtfQR/prQREpyEEcPT. PT QREPT """' / ^RSPH 7FOV I AM: Fig. 12. Eodicynodon oosthuizeni, A. Dorsal view. B. Lateral view of palatoquadrate complex. continued some distance posteriorly. At the break, the quadrate ramus of the epipterygoid has a distinct dorsally directed ridge, which probably represents the basal portion of the dorsally directed columella of the epipterygoid. A separate skull fragment featuring the basicranial axis confirms this view (Fig. 12). Anterior to the base
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. QtfQR/prQREpyEEcPT. PT QREPT """' / ^RSPH 7FOV I AM: Fig. 12. Eodicynodon oosthuizeni, A. Dorsal view. B. Lateral view of palatoquadrate complex. continued some distance posteriorly. At the break, the quadrate ramus of the epipterygoid has a distinct dorsally directed ridge, which probably represents the basal portion of the dorsally directed columella of the epipterygoid. A separate skull fragment featuring the basicranial axis confirms this view (Fig. 12). Anterior to the base of the columella the footplate shows a broad medial expansion which stretches across the dorsal surface of the pterygoid and ends medially against the base of the parabasisphenoid (Fig. 12). The exceptional development of this part of the footplate of the epipterygoid is most unusual for dicynodonts. In the latter the footplate is only weakly developed, or not at all, and the columella is anterior to the base of the columella. In Kannemeyeria (Case 1934) and Daptocephalus (Ewer 1961) the footplate is continued anteriorly but as a much less extensive and narrower bone. Ewer (1961) suggested that this extension was possibly developed to compensate for the weakening of the middle region of the skull resulting from the narrowing of the parietal region. This interpretation does not hold true for Eodicynodon as the parietal region is relatively broad in this form. Being a dicynodont ancestor it is more likely that Eodicynodon would display the more primitive condition. The remarkable simi- larity of the Eodicynodon and Dimetrodon (Romer & Price 1940) footplates would seem to justify this conclusion. The anterior process found in Daptocephalus represents the retention in this form of a primitive feature rather than a later development. In all known Gorgonopsia too the epipterygoid still retains a long tapering anterior extension. As in Pristerodon (Barry 1967) a well-demarcated g
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
