Evolution & Systematics

Within the class Asteroidea, there was an early, but quick diversification. There is currently very little fossil evidence on the family, Ophidiasteridae, making it hard to determine its phylogeny. Although this is the case, it is known from research that Ophidiasteridae is not monophyletic (Mah, 2011). Throughout the Palaeozoic time period, the Asteroidea classification is the most inadequate of all Echinoderm groups (Blake, 1990). Assisting with the division of Asteroidea into orders is the development of the ossicles by means of two very distinct patterns. This division is further enhanced by the unique presence of heavy dermal tissues in the order, Valvatida (Blake, 1990). The overall classification of Asteroidea has been determined by the morphology of the adult skeleton (Vickery, 2000). The phylogenetic tree, shown below, displays the most recent phylogeny of the Class, Asteroidea.