Researchers have elucidated the evolutionary origins of placodes and neural crests, which are defining features of vertebrates, through lineage tracing and genetic analysis in Ciona intestinalis, a marine invertebrate animal. Striking similarities between the patterning of the lateral plate in Ciona and the compartmentalization of the neural plate ectoderm in vertebrates were observed, suggesting that the latter preceded the advent of vertebrates, and served as a common evolution source for placodes and neural crests.