FIGURE 6 in The late Maastrichtian Belemnella kazimiroviensis group (Cephalopoda, Coleoidea) in the Middle Vistula valley (Poland) and the Maastricht area (the Netherlands, Belgium) - taxonomy and palaeobiological implications

FIGURE 6. Diagram illustrating morphological features of the belemnite guard (lateral view of a longitudinally split guard on the left, ventral view on the right). AA = alveolar angle; FA = fissure angle; SD = Schatzky distance; Ls = length from apex to protoconch; Ds, Dp, Dc = dorso-ventral diameters at different part of the rostrum; Bs, Bp, Bc = lateral diameters at different part of the rostrum (after Keutgen, 1997; Keutgen et al., 2012).