. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. MIOCENE VERTEBRATES EROM ARRISDRIFT, SOUTH WEST AFRICA 13. Fig. 4. Occlusal and buccal views of large canoid mandible (AD 1520) from Arrisdrift. later varieties of A. major (see Kuss 1965; Table 3, this report). They do, how- ever, differ in being relatively broad, a feature which applies particularly in the case of P4. Although lost, the P2 and P3 of AD 1520 were evidently also relatively large and, together with P4, formed a closed series. The large size of the premolars distinguishes the Arrisdrif
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. MIOCENE VERTEBRATES EROM ARRISDRIFT, SOUTH WEST AFRICA 13. Fig. 4. Occlusal and buccal views of large canoid mandible (AD 1520) from Arrisdrift. later varieties of A. major (see Kuss 1965; Table 3, this report). They do, how- ever, differ in being relatively broad, a feature which applies particularly in the case of P4. Although lost, the P2 and P3 of AD 1520 were evidently also relatively large and, together with P4, formed a closed series. The large size of the premolars distinguishes the Arrisdrift species from previously recorded A. major and, indeed, from all other Miocene amphicyonids. Apparently only in certain Oligocene species are the premolars relatively large and in the form of a closed series (see Springhorn 1977). If AD 1520 is indeed related to A. major, it must be more primitive than recorded representa- tives of this taxon even though it is 'advanced' in terms of overall size. The origins of A. major are obscure (Kuss 1965) and it may well have arrived in Europe as an immigrant from Africa. The Arrisdrift species may represent the stock from which A. major was derived. There is, however, a second alternative which must be considered. The Hemicyoninae, a group of Miocene ursids which share many characters with amphicyonids, also include a very large species whose origins are obscure. This is Dinocyon thenardi of the later middle Miocene of Europe (Hiirzeler 1944). The hemicyonines also have reduced premolars, although the reduction is not necessarily as marked as in contemporary amphicyonids. They pre- sumably evolved from forms in which the premolars were relatively large and. 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
