Neognaths (Neognathae) are birds that within the subclass Neornithes of the class Aves. The Neognathae include virtually all living birds; their sister taxon Paleognathae contains the tinamous - their only order capable of flight - as well as the flightless ratites.
There are nearly 10.000 species of neognaths. Since the late Cretaceous from where the earliest fossils are known, they have undergone adaptive radiation to produce the staggering diversity of form (especially of the bill and feet), function, and behavior that we see today. The Passeriformes (perching birds) are the largest order of land vertebrates, containing some 60% of living birds and being more than twice as diverse as rodents and about 5 times as diverse as Chiroptera (bats and flying foxes) which are the largest order of mammals. On the other hand, there are some very small orders, usually birds of very unclear relationships like the puzzling Hoatzin.
The neognaths have fused metacarpals, an elongate third finger, and 13 or fewer vertebrae. They differ from the Paleognathae in features like the structure of their jawsbones. "Neognathae" means "new jaws", but ironically it seems that the supposedly "more ancient" paleognath jaws are among the few apomorphic ("more advanced") features of this group as compared to the neognaths.
There are nearly 10.000 species of neognaths. Since the late Cretaceous from where the earliest fossils are known, they have undergone adaptive radiation to produce the staggering diversity of form (especially of the bill and feet), function, and behavior that we see today. The Passeriformes (perching birds) are the largest order of land vertebrates, containing some 60% of living birds and being more than twice as diverse as rodents and about 5 times as diverse as Chiroptera (bats and flying foxes) which are the largest order of mammals. On the other hand, there are some very small orders, usually birds of very unclear relationships like the puzzling Hoatzin.
The neognaths have fused metacarpals, an elongate third finger, and 13 or fewer vertebrae. They differ from the Paleognathae in features like the structure of their jawsbones. "Neognathae" means "new jaws", but ironically it seems that the supposedly "more ancient" paleognath jaws are among the few apomorphic ("more advanced") features of this group as compared to the neognaths.
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