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

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. Defi ning characters is the most important step in systematics and, therefore, we RESUMEN Se realiza un analisis osteologico comparado de vertebras dorsales medias (representadas por V6) utilizando una especie representativa de cada genero de Salamandridae (Amphibia, Caudata). Los caracteres morfologicos cualitativos seleccionados fueron adaptados de los que tradicionalmente se utilizan en paleontologia y con ellos se infi rieron los correspondientes modelos fi logeneticos. La misma matriz morfologica se utilizo de nuevo, pero corregida mediante asignacion de un pesaje diferencial a los caracteres, segun los resultados de un test psicologico realizado por un grupo internacional de estudiantes de doctorado sin relacion con la paleoherpetologia. Los resultados fi logeneticos de ambos grupos se compararon con el modelo evolutivo actualmente aceptado para esta familia, basado en secuencias de genes mitocondriales y nucleares. La ordenacion por perceptibilidad relativa de cada unidad estructural de la vertebra (prezigapofi sis, neurapofi sis, etc.), realizada subjetivamente por el colectivo inexperto, puede suponerse que refl eja la propia capacidad humana para el reconocimiento de formas. El mismo patron perceptivo parece estar tambien presente en el conjunto de caracteres de los especialistas, y con ambas matrices se obtuvieron resultados similares en cuanto a la calidad de sus inferencias Manuscript received 30 April 2012 Manuscript accepted 15 July 2012 © Sociedad Espanola de Paleontologia ISSN 2255-0550 BUCKLEY & SANCHIZ 132