. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 4o ANNALS OF THE SOUTH AFRICAN MUSEUM In the anomodont stem also, when first encountered in the Tapinocephalus zone, a split had already taken place. In the dinocephalian branch the facet on the astragalus for the tibia has moved on to the dorsal surface, whereas in the dicynodont branch this facet still lies proximally. In the dicynodont branch the digits are greatly lengthened with curved claws in the Dromasauria, whereas in the dicynodonts the foot is shortened and carried flat nails. In the Dinoc
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 4o ANNALS OF THE SOUTH AFRICAN MUSEUM In the anomodont stem also, when first encountered in the Tapinocephalus zone, a split had already taken place. In the dinocephalian branch the facet on the astragalus for the tibia has moved on to the dorsal surface, whereas in the dicynodont branch this facet still lies proximally. In the dicynodont branch the digits are greatly lengthened with curved claws in the Dromasauria, whereas in the dicynodonts the foot is shortened and carried flat nails. In the Dinocephalia the L-shape of the astragalus is retained in the titano- suchians and tapinocephalians but is lost in the anteosaurs where the navicular is also lost. Conclusions In my previous attempt to show how in pre- Tapinocephalus zone times the therapsid stem split up dichotomously, I based my views on the cranial features (1963). Here I suggested that the first split was into theriodonts and anomo- donts with a later split by the former into Gorgonopsia and Therocephalia and by the latter into Dicynodontia and Dinocephalia. No such clear-cut dichotomies are evident in the divergent developments seen in the different parts of the girdles and limbs. The rates of development in the various structures are so different that no general pattern of divergence is apparent. But this does not necessarily invalidate the conclusions drawn from the cranial Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original South African Museum. Cape Town : The Museum
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
