Tunicates are the closest relatives of vertebrates and are widely used as</p><p>models to study the evolutionary developmental biology of chordates. Their phylogeny,</p><p>however, remains poorly understood and to date, only the 18S rRNA nuclear gene and</p><p>mitogenomes have been used to delineate the major groups of tunicates. To further</p><p>resolve their evolutionary relationships and provide a first estimate of their divergence</p><p>times, we used a transcriptomic approach to build a supermatrix consisting of 258</p><p>evolutionarily conserved orthologous genes for representative species of all major</p><p>tunicate lineages.