. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history; Natuurlijke historie; Sociale geschiedenis; Culturele antropologie. 158 ANNALS OF THE SOUTH AFRICAN MUSEUM in sample 818 is 93 per cent (number of specimens), which is higher than in any other sample from the Campanian-Maastrichtian rocks of south-east Africa. Significantly, however, the next highest values recorded (76%, mean of 6 samples) were from the populations of assemblage /o TR ACHY LEBER I Dl DAE Fig. 74. Fields for ostracod assemblages 1-7 on a percentage Bairdiacea (total fauna) v. per
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history; Natuurlijke historie; Sociale geschiedenis; Culturele antropologie. 158 ANNALS OF THE SOUTH AFRICAN MUSEUM in sample 818 is 93 per cent (number of specimens), which is higher than in any other sample from the Campanian-Maastrichtian rocks of south-east Africa. Significantly, however, the next highest values recorded (76%, mean of 6 samples) were from the populations of assemblage /o TR ACHY LEBER I Dl DAE Fig. 74. Fields for ostracod assemblages 1-7 on a percentage Bairdiacea (total fauna) v. percentage Trachyleberididae (of Cytheracea) plot. Sample 818 from the Agulhas Bank lies near the Bairdiacea baseline, on the RHS of the diagram. See text for explanation. Contrasts with typical populations in assemblage 3 makes the assessment of a palaeosedimentary environment for sample 818 uncertain. Despite the differ- ences mentioned above, however, the overall composition of the population of sample 818 places it firmly within the shallow-water area of the CCBC diagram. Nevertheless, the overwhelming blindness of the fauna and the presence of elements which are typically indicators of deeper water show that sample 818 was not deposited in a near-shore or even mid-shelf environment, as were the assemblage 3 populations in the BH-9 borehole. This uniqueness can be further emphasized by comparing the trachyleberid percentage of the Cytheracea of all the Zululand Santonian-Maastrichtian samples to some parameter that is inde- pendent of the cytheracean component, such as the Bairdiacea percentage. Figure 74 shows a progressive increase in the trachyleberid component of the Cytheracea with increase in water depths and open oceanic influences up the BH-9 borehole to a point where moderate water depths replace shallow ones. Movement of the assemblage fields representative of deeper-water environments is in the reverse direction, with the bulk of the deep-water assemblages (5b, 6 an
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