Fig. 4 in Piggyback whorls: A new theoretical morphologic model reveals constructional linkages among morphological characters in ammonoids

Fig. 4. Schematic diagram of an ammonoid whorl section. The shape of the whorl (S) is represented by the closed curve illustrated here which is given by the parametric equations indicated above the diagram. Figures in the right show examples of hypothetical whorl shapes with systematically varying the S value.