. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE AMMONITE FAMILY BACULITIDAE 69 Cobban & Kennedy 1991a, pi. 1 (figs 7-10). In some Baculites, the aperture is distinctly flared, B. obtusus in Birkelund (1965, pi. 13 (fig. 2a-c)); B. asperiformis Meek in Cobban (1962&, pi. 106 (figs 14-16)) and some B. vanhoepeni, or associated with a slight constriction, B. rex Anderson in Matsumoto (1959, pi. 40 (fig. la-c)) or B. subanceps Haughton (as B. aff. anceps in Matsumoto 1959: 140). According to Birkelund (1965: 62), there seems to b
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE AMMONITE FAMILY BACULITIDAE 69 Cobban & Kennedy 1991a, pi. 1 (figs 7-10). In some Baculites, the aperture is distinctly flared, B. obtusus in Birkelund (1965, pi. 13 (fig. 2a-c)); B. asperiformis Meek in Cobban (1962&, pi. 106 (figs 14-16)) and some B. vanhoepeni, or associated with a slight constriction, B. rex Anderson in Matsumoto (1959, pi. 40 (fig. la-c)) or B. subanceps Haughton (as B. aff. anceps in Matsumoto 1959: 140). According to Birkelund (1965: 62), there seems to be some variation in the aperture of B. obtusus; some specimens, Birkelund (1965, pi. 10 (fig. la-c)) have less-inflated apertures; others, as mentioned above (p. 59), retain traces of an early flared aperture on the phragmocone. In the South African material, the disparate sizes at which apertures are formed in B. capensis (Fig. 51), B. sulcatus and B. vanhoepeni (Fig. 53) is striking. In small specimens the apertures are usually slightly flared, whereas in larger specimens this is less apparent, but this feature does not seem to be consistent. Where large samples are available, in B. capensis (Fig. 52) and B. vanhoepeni (Fig. 53), there seems to be a gradation from large to small specimens with apertures, with no distinct, separate double peaks, indicating micro- and macroconchs. This shows that there is a considerable degree of overlap in size at which micro- and macroconchs form apertures. However, the difference in size between the largest macroconch and the smallest microconch is impressive. 20 1Q Size distribution in Baculites capensis 0indicates distribution of specimens with preserved 15 20 MAXIMUM WHORL HEIGHT IN MM Fig. 52. Histogram illustrating size distribution in Baculites capensis Woods, 1906, to illustrate Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability
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