Comparative shell shape distributions in Jurassic-Cretaceous ammonites and Jurassic-Tertiary nautilids

Abstract

Contours of whorl expansion rate (W), distance of the generating curve from the axis of coiling (D) and shape of the generating curve (S) were plotted from data on 988 Jurassic through Cretaceous ammonite species and 205 Jurassic through Tertiary nautilid species. The areas occupied by the ammonites and nautilids are largely nonoverlapping when plotted asWDandDSgraphs.