ABSTRACT

The Radiasteridae (Asteroidea) is a small family hitherto lacking a known fossil record. Living representatives of the family are uncommon and their geographically scattered distribution suggests a relict status. The family has long been considered to be of uncertain affinities. Many paxillosidan genera are morphologically very similar to certain valvatidans, suggesting a close common ancestry. A computer-based cladistic analysis of certain pertinent taxa was undertaken using PAUP 3.1. A variety of taxa and data sets were employed treating three to seven families and 14 to 18 genera. Results varied with taxa and data sets but inconsistent results appeared to track body construction rather than phylogeny. That is, although morphologically varied, asteroids tend to be either comparatively robust, with closely arranged ossicles and stout spinelets and granules.