Arrangement of the Hox cluster in major deuterostome clades. Evx and Mox genes, located in the vicinity of the Hox cluster, are also indicated. Tree topology is a synthesis of [17, 23], and  for echinoderm clades. Terminals are based on data from taxa as follows: derived vertebrates on Mus (mouse); basal vertebrates on Lethenteron (lamprey); larvacean urochordates on Oikopleura; ascidian urochordates on Ciona; cephalochordates on Branchiostoma (amphioxus); hemichordates on Saccoglossus (acorn worm); crinoids on a combination of Metacrinus (sea lily) and Oxycomanthus (feather star); asteroids on a combination of Asterias and Patiriella (starfish); ophiuroids on Stegophiura (brittle star); holothuroids on Holothuria (sea cucumber); and echinoids on Strongylocentrotus (purple sea urchin). Note that for echinoderms, the alignments for the anterior class are shown in the recently discovered translocated, inverted condition. The nature of the lines through the complex on the right denotes the position of genes on a single (one continuous line), on few (several broken lines), or on many (no line) chromosomes. Putative arrangements are shown by dashed lines.