Meeting Abstract

P1.201  Saturday, Jan. 4 15:30  Developmental Reaction Norms in the Phenotypes of Scutelliform Echinoid Skeletons ZACHOS, L G; University of Mississippi lgzachos@olemiss.edu

Using a holistic morphometric method based on Geographic Information System technology, recurring themes (developmental reaction norms) in phenotypic expression of skeletal architectures are demonstrated for a group of scutelliform sand dollar echinoids. In particular, similarities in the expression of timing of imago to post-imago stage transitions, juvenile through adult plate growth, aboral-oral plate dependencies, translocation of ambulacral and interambulacral plates, and asymmetric radial expansion can be shown for the extinct Protoscutellidae and extant Echinarachniidae. Distinct morphotypes in a single population of Echinarachnius parma, defined using information from all the plates in the skeleton and complete ontogenetic trajectories, are compared with similarly examined morphospecies of protoscutellids. This information is critical to unraveling both the taxonomy and the phylogeny of the Protoscutellidae.