Neognathae

Neognathae, meaning "new jaws," is a clade within the class Aves that comprises the vast majority of living bird species. It is one of the two major divisions of modern birds, the other being Palaeognathae, which includes the flightless ratites and the tinamous. Tinamous are typically placed in Palaeognathae, so Neognathae excludes these taxa.

Systematics within Neognathae are commonly divided into two principal lineages: Gallanserae (Galloanserae) and Neoaves. Galloanserae includes the waterfowl (ducks, geese, swans) and gamebirds, while Neoaves encompasses the remaining orders, such as passerines (perching birds), birds of prey, shorebirds, seabirds, parrots, and many others. This grouping reflects major evolutionary splits that developed after the divergence from Palaeognathae.

Characteristics of Neognathae are defined largely by skeletal and skull features, especially a more derived palate and greater cranial kinesis compared with palaeognaths. These anatomical traits, together with molecular data, support Neognathae as a monophyletic group. While many neognaths are strong fliers, the clade also includes numerous flightless or weakly flying lineages, illustrating considerable ecological diversity.

Evolutionary history for Neognathae is anchored in the Cretaceous period, with estimates placing the split from Palaeognathae in the Early to mid-Cretaceous, around 100–95 million years ago. Today, Neognathae accounts for the majority of living birds, exceeding ten thousand species across numerous orders and occupying a wide range of ecological niches.