Fig. 9
From: Interpreting drag consequences of ammonoid shells by comparing studies in Westermann Morphospace
Shell shape parameters of shells of all Neogastroplites specimens included in Yacobucci (2004), calculated following Ritterbush and Bottjer (2012). Triangles indicate the first chronospecies, N. haasi. Filled circles indicate the final chronospecies, N. maclearni. Note that whorl expansion (b) is the observed expansion of the aperture at a half-whorl rotation, rather than the asserted logarithmic expansion. Values of all three variables are significantly higher in N. haasi, though the difference is most apparent in umbilical exposure (a) and whorl expansion (b)