Figure 1.

Evolutionary relationships of early-diverging metazoan lineages (Symplasma, Cellularia, Ctenophora, Placozoa, Anthozoa, and Medusozoa) with Bilateria and outgroups (Plantae, Fungi, and Choanoflagellata). Tree topology is based on [77]. Dotted line indicates uncertainty as to the placement of the placozoan branch. Arrows indicate the earliest known appearance of the specified group of genes.