MARTINDALE, m.q.*; FINNERTY, J.: Developmental patterning in “pre-bilaterians”: Can we get there from here?

A great deal of attention has been focused on the conservation of cellular and molecular developmental mechanisms of bilaterian metazoans. Scenarios have been based primarily on data obtained from only a handful of model systems. As the data from disparate protostomes and deuterostomes gets distilled, it must be remembered that bilaterians are most likely derived from ?radially? symmetrical forms. This talk will review features of the development of the extant radial eumetazoan phyla, the cnidarians and ctenophores, in the context of developing potential evolutionary links to bilaterians. Of particular interest are factors related to the origins of adult symmetry properties, the origin of mesoderm, and the presence and deployment of Hox genes. Piecing together the ancestry of bilaterian features and the direction of evolutionary change will depend on the identification of the true sister group to the Bilateria. This work was supported by the NASA, NSF and the Woods Hole MBL fellowship