Suliformes

The order Suliformes (, dubbed "Phalacrocoraciformes" by "Christidis & Boles 2008") is an order recognised by the International Ornithologist's Union. In regard to the recent evidence that the traditional Pelecaniformes is polyphyletic, it has been suggested that the group be split up to reflect the true evolutionary relationships, a 2017 study indicated that they are most closely related to Phaethontiformes (tropicbirds) and Ciconiiformes (storks).
Systematics and evolution.
Of the families in Pelecaniformes, only Pelecanidae, Balaenicipitidae, and Scopidae remain. The tropicbird family Phaethontidae has since been moved to their own order Phaethontiformes. Genetic analysis seems to show that the Pelecaniformes is actually closely related to the Ardeidae and Threskiornithidae. As for the Suliformes, they are distantly related to the current Pelecaniformes. According to Hackett "et al". (2008), loons, penguins, storks, and as well as Suliformes and Pelecaniformes, all seem to have evolved from a common ancestor. The proposed waterbird superorder has been suggested.
In their landmark 2008 work "Systematics and Taxonomy of Australian Birds", Australian ornithologists Les Christidis and Walter E. Boles coined the name Phalacrocoraciformes for the group due to the much greater number of species of cormorants (Phalacrocoracidae) over boobies and gannets (Sulidae). However, this has not been taken up elsewhere.
In 1994, American ornithologist Walter J. Bock wrote that the name Suloidea had been used consistently as a term for a superfamily containing the two families, so therefore "Sulidae" and not "Phalacrocoracidae" should take priority in any arrangement containing the two genera.
In 2010, the AOU adopted the term Suliformes for the taxon. The IOC followed in 2011.
In 1994, Martyn Kennedy and colleagues constructed a behavioural data set, with the resulting tree showing a high level of congruence with existing phylogenies based on genetics or morphology. It showed the darters as sister group to the cormorants and shags, with the gannets and boobies, then pelicans, then frigatebirds and lastly tropicbirds as progressively earlier offshoots.
Cladogram based on Gibb, G.C. "et al". (2013)