Fig. 3 Some postulated relationships among the five main metazoan clades. a in Higher-level metazoan relationships: recent progress and remaining questions

Fig. 3 Some postulated relationships among the five main metazoan clades. a Traditional hypothesis based on morphology, with sponges as sister group to other metazoans (e.g. Nielsen 2001). b Hypothesis based on phylogenomic analyses, with ctenophores as sister group to all other metazoans (Dunn et al. 2008; Hejnol et al. 2009). c