. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . mi Jfm. Figure 15 Nostoceras (Bostrychoceras) sanctaeluciense (Klinger, 1976). SAS-Z762, the holotype fromlocality 119, KwaZulu, St Lucia Formation, Maastrichtian a or b. x However, as the dimensions indicate, there seems to be a nearly continuous growth seriesfrom smallest to largest. If this size difference is indeed due to dimorphism, there is a largedegree of overlap in size between microconchs and macroconchs. There are, however,other differences between the small and large specimens. In the smallest speci
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . mi Jfm. Figure 15 Nostoceras (Bostrychoceras) sanctaeluciense (Klinger, 1976). SAS-Z762, the holotype fromlocality 119, KwaZulu, St Lucia Formation, Maastrichtian a or b. x However, as the dimensions indicate, there seems to be a nearly continuous growth seriesfrom smallest to largest. If this size difference is indeed due to dimorphism, there is a largedegree of overlap in size between microconchs and macroconchs. There are, however,other differences between the small and large specimens. In the smallest specimens, thebody chamber occupies very little of the spiral part of the shell. More important, perhaps,is the fact that the retroversal loop is suspended perpendicularly below the base of the 256 ANNALS OF THE SOUTH AFRICAN MUSEUM. V* Figure 16 Nostoceras (Bostiychoceras) sanctaeluciense (Klinger, 1976). SAS-Z762, the hole-type from locality119, KwaZulu, St Lucia Formation, Maastrichtian a or b. X Fig. 17. {see facing page). Nostoceras (Bostiychoceras) sanctaeluciense (Klinger, 1976). A, 10490a, b, part and counterpart of the very early helical whorls. Note the very early onsetof helical coiling and apparent absence of irregularly coiled early stage. From locality 125,KwaZulu. B. SAM-PCZ 10489. Note the development of large, lateral spines on thickened locality 119, KwaZulu. D. SAM-PCZ 10496. Ventral view of part of phragmocone showingventral tubercles. From locality 113, KwaZulu. All from the St Lucia Formation, Maastrichtian a orb. All x 1. CRETA CEOUS FA UNAS FROM ZUL ULAND AND NA TAL, SOUTH AFRICA 257
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