Phenotypic plasticity of Acanthoscaphites tridens (Late Cretaceous ammonites): additional data

The concept of phenotypic plasticity of the temporal species Acanthoscaphites tridens s. str., as recently proposed by myself is elaborated upon, in response to issues raised in a commentary to the original paper. The terms phenomorphic class and dominant phenotype are explained in greater detail, as well as the evaluation of phenotypic plasticity in studies for extinct species.