Should the terms ‘basal taxon’ and ‘transitional taxon’ be extinguished from cladistic studies with extinct organisms?

Abstract

The terms basal and transitional have been widely adopted to designate the condition or nature of taxa in a phylogenetic context. Because they are taken as informative, some authors might even use these terms in an attempt to enhance the perceived value of a particular fossil discovery. Nevertheless, basal and transitional are most of the times erroneously or inconsistently applied, or are redundant to the arguments or quality of a scientific work and/or condition of taxa. In some cases, they can lead to the idea that the evolution of a lineage happened toward a specific group, in a mode of teleological reasoning. Here I illustrate problematic issues that can arise from this varied use of both terms. Finally, it is shown how statements that are in accordance with the cladistic method can substitute both terms in order to avoid pointless or misleading information.