Untrained versus specialized palaeontological systematics: A phylogenetic validity test using morphostructural conspicuity as character weight

Abstract

We performed a comparative osteological analysis of middle trunk vertebrae (represented by V6) of representative species of all living genera of Salamandridae (Amphibia, Caudata). The qualitative morphological characters used were adapted from the traditional palaeontological literature; using this data set we inferred a phylogenetic hypothesis for the family. The same morphological matrix was then re-analysed using a weighting scheme for the characters derived from the answers of a psychological test taken by an international group of graduate students unfamiliar with palaeoherpetology. We compared the phylogenetic results of both groups with the currently accepted evolutionary model for this family, which is based on mitochondrial and nuclear gene sequences. The ranking of the relative (and subjective) conspicuity of vertebral structural units (prezygapophyses, neurapophyses, etc.) collectively made by the inexpert group, presumably, directly derives from a general (human) capability to recognise shapes. The same perceptive pattern also seems to be involved in the character set developed by the specialists, and both matrices obtained similar results in the quality of their respective phylogenetic inferences. Defining characters is the most important step in systematics and, therefore, we stress the importance of developing new tools and approaches for exploring new quantitative and qualitative characters in palaeontological research