Heterochrony in helicoid spiral cones: A computer model for demonstrating heterochronic evolution

Abstract

A modification of Raup’s classic helicoid logarithmic spiral cone model allows the incorporation of parameters for ontogenetic change in the main geometrical parameter values. The resulting allometric structures can be modified by simulated heterochronic increments so that the effects of neoteny, acceleration, progenesis and hypermorphosis can be produced. Experiments with the model, named HETEROSIM, produce suites of forms that are consistent with those that occur within Families of the Class Gastropoda, and hence heterochrony is a plausible hypothesis for evolution in those taxa. In addition to applications in evolutionary research, the model is a valuable pedagogic tool in teaching advanced palaeontology and evolution.