Figure 1. Recent estimates of higher-level waterbird phylogeny based on morphological and molecular datasets.

(A) Topology recovered in the parsimony analysis of morphological data by Livezey and Zusi [4], with common names and silhouettes of taxa indicated to the right. (B) Topology recovered in the maximum likelihood analysis of molecular data by Hackett et al. [29]. Double hash marks in (B) indicate that the clade containing Phaethon, Podiceps, and Phoenicopterus is actually recovered as distantly related to the waterbird clade (i.e., is not its sister-taxon). Branch colors represent traditional avian orders: Gaviiformes (purple); Podicipediformes (yellow); Sphenisciformes (brown); Procellariiformes (blue); Ciconiiformes (orange); Pelecaniformes (green). Note that for the purposes here, Phoenicopterus is considered as being traditionally allied with Ciconiiformes, though it could also be treated as the monotypic order Phoenicopteriformes. Several taxa that were not shared by both datasets were pruned from the trees. Bootstrap values ≥70% are indicated above nodes. Nodes that conflict between topologies are indicated with red circles.