. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . , however, ornament differs between thephragmocone and body chamber. Internal moulds of the phragmocone are usually(Figs 2B, 3-4), but not always (Figs 1, 2A, C-D) smooth whereas internal moulds of thebody chamber retain the ribbing. This conspicuous anomaly has been noted on severaloccasions (see Olivero & Zinsmeister 1989: 627; Henderson et al. 1992: 141; Kennedy1999: 657), and according to Olivero & Zinsmeister (1989), can be ascribed to thethickening of the nacreous shell layer below the ribs on the phragmocone,
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . , however, ornament differs between thephragmocone and body chamber. Internal moulds of the phragmocone are usually(Figs 2B, 3-4), but not always (Figs 1, 2A, C-D) smooth whereas internal moulds of thebody chamber retain the ribbing. This conspicuous anomaly has been noted on severaloccasions (see Olivero & Zinsmeister 1989: 627; Henderson et al. 1992: 141; Kennedy1999: 657), and according to Olivero & Zinsmeister (1989), can be ascribed to thethickening of the nacreous shell layer below the ribs on the phragmocone, and may beconsidered diagnostic of the genus Diplomoceras. Apart from shell structure, the latterauthors also provided details of muscle scars, previously recorded by Jones (1961), andspeculated on the mode of life and buoyancy control of Diplomoceras. The suture line(Fig. 7A-C) is deeply incised with a large bifid lateral (L) and umbilical (U) lobe, and asmall, trifid internal (/) lobe. The saddles all have very narrow stems. 174 ANNALS OF THE SOUTH AFRICAN MUSEUM. / : ????? - ?- ??,!--%„
Size: 2061px × 1212px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booki, booksubjectnaturalhistory
