The Pelecaniformes are an order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such names as totipalmates or steganopodes. Most have a bare throat patch, and the nostrils have evolved into dysfunctional slits, forcing them to breathe through their mouths. They also have a pectinate nail on their longest toe. This is shaped like a comb and is used to brush out and separate their feathers. They feed on fish, squid, or similar marine life. Nesting is colonial, but individual birds are monogamous. The young are altricial, hatching from the egg helpless and naked in most. They lack a brood patch.
Otidae is a clade that includes the superorders Otidimorphae and Strisores. It was identified in 2014 by genome analysis. Earlier it was thought that Strisores was closely related to birds such as pigeons, flamingos, tropicbirds, and the sunbittern and kagu in the taxon Metaves, but subsequent work has provided evidence that Metaves is polyphyletic. Although analyses of genome data provided relatively high support for monophyly of Otidae, indicating that it occupies a basal branch of the clade Passerea, other analyses of large data matrices have not recovered a clade comprising Otidimorphae and Strisores, raising questions about the monophyly of Otidae.
The mesites (Mesitornithidae) are a family of birds that are part of a clade (Columbimorphae) that include Columbiformes and Pterocliformes. They are smallish flightless or near flightless birds endemic to Madagascar. They are the only family with more than two species in which every species is threatened.
Neoaves is a clade that consists of all modern birds with the exception of Palaeognathae and Galloanserae. Almost 95% of the roughly 10,000 known species of extant birds belong to the Neoaves.
Mirandornithes is a clade that consists of flamingos and grebes. Many scholars use the term Phoenicopterimorphae for the superorder containing flamingoes and grebes.
Aequornithes, or core water birds, are defined as "the least inclusive clade containing Gaviidae and Phalacrocoracidae".
The order Falconiformes is represented by the extant family Falconidae and a handful of enigmatic Paleogene species. Traditionally, the other bird of prey families Cathartidae, Sagittariidae (secretarybird), Pandionidae (ospreys), Accipitridae (hawks) were classified in Falconiformes. A variety of comparative genome analysis published since 2008, however, found that falcons are part of a clade of birds called Australaves, which also includes seriemas, parrots and passerines. Within Australaves falcons are more closely related to the parrot-passerine clade (Psittacopasserae), which together they form the clade Eufalconimorphae. The hawks and vultures occupy a basal branch in the clade Afroaves in their own clade Accipitrimorphae, closer to owls and woodpeckers.
Strisores, sometimes called nightbirds, is a clade of birds that includes the living families and orders Caprimulgidae, Nyctibiidae (potoos), Steatornithidae (oilbirds), Podargidae (frogmouths), Apodiformes, as well as the Aegotheliformes (owlet-nightjars) whose distinctness was only recently realized. The Apodiformes and the Aegotheliformes form the Daedalornithes.
Australaves is a recently defined clade of birds, consisting of the Eufalconimorphae as well as the Cariamiformes. They appear to be the sister group of Afroaves. As in the case of Afroaves, the most basal clades have predatory extant members, suggesting this was the ancestral lifestyle; however, some researchers like Darren Naish are skeptical of this assessment, since some extinct representatives such as the herbivorous Strigogyps led other lifestyles. Basal parrots and falcons are at any rate vaguely crow-like and probably omnivorous.
Afroaves is a clade of birds, consisting of the kingfishers and kin (Coraciiformes), woodpeckers and kin (Piciformes), hornbills and kin (Bucerotiformes), trogons (Trogoniformes), cuckoo roller (Leptosomiformes), mousebirds (Coliiformes), owls (Strigiformes), raptors (Accipitriformes) and New World vultures (Cathartiformes). The most basal clades are predatory, suggesting the last common ancestor of Afroaves was also a predatory bird.
Telluraves is a recently defined clade of birds defined by their arboreality. Based on most recent genetic studies, the clade unites a variety of bird groups, including the australavians as well as the afroavians. They appear to be the sister group of the Ardeae.
Passerea is a clade of neoavian birds that was proposed by Jarvis et al. (2014). Their genomic analysis recovered two major clades within Neoaves, Passerea and Columbea, and concluded that both clades appear to have many ecologically driven convergent traits.
Eurypygimorphae or Phaethontimorphae is a clade of birds that contains the orders Phaethontiformes (tropicbirds) and Eurypygiformes recovered by genome analysis. The relationship was first identified in 2013 based on their nuclear genes. Historically these birds were placed at different parts of the tree, with tropicbirds in Pelecaniformes and the kagu and sunbittern in Gruiformes. Some genetic analyses have placed the eurypygimorph taxa in the controversial and obsolete clade Metaves, with uncertain placement within that group. More recent molecular studies support their grouping together in Eurypygimorphae, which is usually recovered as the sister taxon to Aequornithes within Ardeae.
Phaethoquornithes is a clade of birds that contains Eurypygimorphae and Aequornithes, which was first recovered by genome analysis in 2014. Members of Eurypygimorphae were originally classified in the obsolete group Metaves, and Aequornithes were classified as the sister taxon to Musophagiformes or Gruiformes.
Coraciimorphae is a clade of birds that contains the order Coliiformes (mousebirds) and the clade Cavitaves. The name however was coined in the 1990s by Sibley and Ahlquist based on their DNA-DNA hybridization studies conducted in the late 1970s and throughout the 1980s. However their Coraciimorphae only contains Trogoniformes and Coraciiformes.
Eucavitaves is a clade that contains the order Trogoniformes (trogons) and the clade Picocoraciae. The name refers to the fact that the majority of them nest in cavities.
Picocoraciae is a clade that contains the order Bucerotiformes and the clade Picodynastornithes supported by various genetic analysis and morphological studies. While these studies supported a sister grouping of Coraciiformes and Piciformes, a large scale, sparse supermatrix has suggested alternative sister relationship between Bucerotiformes and Piciformes instead.
Columbimorphae is a clade discovered by genome analysis that includes birds of the orders Columbiformes, Pterocliformes (sandgrouse), and Mesitornithiformes (mesites). Previous analyses had also recovered this grouping, although the exact relationships differed. Some studies indicated a sister relationship between sandgrouse and pigeons while other studies favored a sister grouping of mesites and sandgrouse instead.
Picodynastornithes is a clade that contains the orders Coraciiformes and Piciformes. This grouping also has current and historical support from molecular and morphological studies.
Pelecanimorphae is a clade of aequornithean birds that comprises the orders Ciconiiformes, Suliformes and Pelecaniformes. In the past the name has been used as a homonym for Pelecaniformes.
