Neognathae

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Neognaths
Fossil range: Late Cretaceous - Present
Male Mandarin Duck, Aix galericulata(Galloanserae: Anseriformes: Anatidae)
Male Mandarin Duck, Aix galericulata
(Galloanserae: Anseriformes: Anatidae)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Subclass: Neornithes
Infraclass: Neognathae
Superorders

Galloanserae
Neoaves

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.

Contents

[edit] Taxonomy and systematics

The Great Crested Grebe (Podiceps cristatus), despite its looks, belongs to the closest living relatives of flamingos.
The Great Crested Grebe (Podiceps cristatus), despite its looks, belongs to the closest living relatives of flamingos.

For long the Neognathae were ranked as a superorder and not subdivided any further, because no attempt to do so - for example in the Conspectus of Charles Lucien Bonaparte - were never accepted even by a significant majority of ornithologists. Indeed, until the 1980s there was little subdivision of the Aves in general, and even less of phylogenetic merit. Since then, the availability of massive amounts of new data from fossils - especially Enantiornithes and other Mesozoic birds - as well as from molecular (DNA and protein) sequences has allowed to refine the classification. With new groups of neognath orders being verified, the taxonomic rank of the group needed to shift. In fact, most researchers have by now employed the unranked taxa of phylogenetic nomenclature.[1]

Domestic chicken belong to the fowl clade, Galloanserae.
Domestic chicken belong to the fowl clade, Galloanserae.
Pacific Golden Plover (Pluvialis fulva), part of the diverse and ancient Charadriiformes.
Pacific Golden Plover (Pluvialis fulva), part of the diverse and ancient Charadriiformes.
The Red-legged Crake (Rallina fasciata) belongs to the Gruiformes - unlike several other birds usually placed there.
The Red-legged Crake (Rallina fasciata) belongs to the Gruiformes - unlike several other birds usually placed there.
Black Kites (Milvus migrans) like other accipitrids have peculiar chromosomes. This has much confounded molecular phylogeny.
Black Kites (Milvus migrans) like other accipitrids have peculiar chromosomes. This has much confounded molecular phylogeny.
Male Red Bird of Paradise (Paradisaea rubra) - a spectacular passerine.
Male Red Bird of Paradise (Paradisaea rubra) - a spectacular passerine.

The Neognathae are universally accepted to subdivide into two lineages - the "fowl" clade Galloanseres and the Neoaves (sometimes called "higher neognaths"). The subdivisions of the latter are still not well resolved, but several monophyletic lineages have been proposed, such as the Mirandornithes, Cypselomorphae or Metaves and Coronaves. While groups such as the former two - uniting a few closely-related orders - are robustly supported, this cannot be said for the Metaves-Coronaves division for which there is no material evidence at present while the Mesozoic record of Neognathae is at present utterly devoid of birds that would have to be present if these proposed clades were real.[2]

Taxonomic note:
The ranks used here are rarely employed in the literature. The ultimate reason is a limitation in the Wikipedia taxobox code, which does not allow for an arbitrary number of "unranked" taxa to be displayed. As the taxa used here have all been validly described and neither the ICZN nor any other authority regulates their employment, the present ranking is as valid as any other - perhaps even more - and given the technical limitations the only system that can currently be used within the scope of Wikipedia. More commonly found is the old placement as a superorder - but such systematic treatments need to be viewed with caution, as they often do not even incorporate the Galloanserae - or as unranked clade.

[edit] Systematics

The orders are arranged in a sequence that attempts to follow the modern view on neognath phylogeny. It differs from the widely-used Clements taxonomy as well as from the Sibley-Ahlquist taxonomy, combining those elements from each that more modern research agrees with while updating those that are refuted. The result is at least a much better representation of the true evolutionary relationships of neognath orders. Most of the changes affect those "higher landbirds" that are sometimes united as near passerines.[3]


[edit] See also

[edit] References

  1. ^ Mindell & Brown (2005)
  2. ^ For a draft phylogeny of Neoaves that is based on a review of massive amounts of published sources and probably rather close to "the real thing", see Mindell et al. (2005)
  3. ^ Mindell et al. (2005)
  • Mindell, David P. & Brown, Joseph W. (2005): The Tree of Life Web Project - Neornithes. Version of 2005-DEC-14. Retrieved 2008-JAN-08.
  • Mindell, David P.; Brown, Joseph W. & Harshman, John (2005): The Tree of Life Web Project - Neoaves. Version of 2005-DEC-14. Retrieved 2008-JAN-08.
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Archosauromorphs
Kingdom: Animalia · Phylum: Chordata · Class: Sauropsida · Subclass: Diapsida
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