Six strongly supported supra-ordinal clades were omitted from Table 1 (indicated with red asterisks in Figure 1). Four of these clades correspond to the major divisions in the avian tree of life: Palaeognathae (Struthioniformes and Notopalaeognathae), Galloanserae (or Galloanseres [68]; Galliformes and Anseriformes), Neoaves (all other extant birds) and Neognathae (Galloanserae and Neoaves). These clades have received extensive independent corroboration (reviewed by Cracraft et al. [69]). Daedalornithes (Aegotheliformes and Apodiformes [70]) and Mirandornithes (Podicipediformes and Phoenicopteriformes [71]) are also very strongly supported. These groups are typically recovered in phylogenetic trees based upon single genes (examples of individual gene analyses that support some or all of these groups include those based upon RAG1 [72±74], EGR1 [73] and up to 18 additional genes [13,75]). Thus, although these groups correspond to supra-ordinal clades, they do not represent difficult tests for phylogenetic methods.