A reevaluation of the origin of pentadactyly

Abstract

The hypothesis suggested by Coates that pentadactyly arose twice is based on the presumed affinities between Tulerpeton, embolomeres, and amniotes. Flaws were found in the coding of some characters that supported this clade and, once corrected, the matrix fails to support the proposed phylogeny. Furthermore, interpretation of the phylogeny of Coates is difficult because no amniotes and no lissamphibians were included m this analysis. A reappraisal of the affinities of Tulerpeton using a matrix composed of a greater range of taxa suggests that it is a stem-tetrapod, that pentadactyly arose only once, and that the first tetrapod was already pentadactyl.