Phylogeny of early deuterostomes
Analogues of organs of special sense may develop in lower chordates.
Shu DG et al. Nature 430: 422-428, 2004
Phylogeny of early deuterostomes
Green arrow: Jeffery WR et al, Nature 431:696-699, 2004
Suggests that neural crest cell evolution (migration from neural tube to body wall, differentiation into pigment cells) began in common ancestor of urochordates and vertebrates.