Meeting Abstract

S9-1.1  Saturday, Jan. 7  The Cambrian Conundrum: Early divergence and later ecological success in the early history of animals SPERLING, Erik*; ERWIN, Douglas; LAFLAMME, Marc; TWEEDT, Sarah; PISANI, Davide; PETERSON, Kevin; Harvard University; Smithsonian National Museum of Natural History; Smithsonian National Museum of Natural History; Smithsonian National Museum of Natural History; National University of Ireland, Maynooth; Dartmouth College sperling@fas.harvard.edu

The sudden appearance of diverse bilaterian clades during the early Cambrian remains a contentious subject, with a range of proposed environmental, developmental, and ecological causes. A new compilation of the patterns of fossil diversification, new molecular clock results and comparative developmental data, and information on ecological feeding strategies illustrate a lag between the divergence of major metazoan clades and the establishment of their developmental toolkits during the Cryogenian, and their later ecological success during the Ediacaran and Cambrian Periods. Bilaterian crown groups appeared during the Ediacaran and Cambrian, largely coincident with the canonical ‘Cambrian Explosion’. We argue that their diversification involved the establishment of controls on cellular differentiation and new forms of developmental regulation, as well as innovations in networks of ecological interaction within the context of permissive environmental circumstances.