Neoaves

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Neoaves are the group that includes almost all living birds. They do not include the two ancient lineages of flightless birds (Palaeognathae, like ostriches) or the big group that contains ducks and chickens (Galloanserae). In simple terms, Neoaves are nearly all modern birds.

Key facts
- Time: Neoaves likely appeared in the late Cretaceous (around 72 million years ago) and diversified rapidly after the mass extinction at the K–Pg boundary.
- Size: About 95% of all living bird species, roughly 10,000 species.
- Definition: A crown group defined as the closest common ancestor of the house sparrow and all its descendants, but not the ancestor of fowl.

Why it’s hard to draw a clear family tree
- After their rapid early diversification, scientists have struggled to agree on exactly how all the groups relate to each other.
- Large genomic studies have proposed different “big picture” splits, and some analyses even suggest multiple equally plausible roots (hard polytomies) rather than a single clear arrangement.
- Despite debates, researchers agree on several large, recognizable groups within Neoaves, sometimes called the “magnificent seven” plus a few additional orders.

Major groups and concepts
- Mirandornithes: flamingos and grebes
- Columbimorphae: pigeons, mesites, sandgrouse
- Otidimorphae: cuckoos, bustards, turacos
- Strisores: hummingbirds, swifts, nightbirds
- Opisthocomiformes: hoatzin
- Gruiformes: cranes and rails
- Charadriiformes: shorebirds
- Eurypygimorphae: sunbittern, kagu, tropicbirds
- Aequornithes: core waterbirds (the big water-loving group)
- Telluraves: core landbirds (the main land-dwelling birds)

Where scientists stand now
- Some analyses support a major division into Columbea and Passerea, but other studies disagree.
- A widely discussed idea is a hard polytomy at the base of Neoaves, meaning the very earliest splits might be unresolved.
- Phaethoquornithes is another arrangement that some researchers find well supported.

In short, Neoaves is the vast group containing almost all living birds, formed after a rapid early diversification. Researchers continue to refine how all its major lineages fit together, with several competing but overlapping ideas about the deepest relationships.