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Modern birds
Fossil range: Late Cretaceous–Recent, 66–0 Ma
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Ostrich, a paleognath
Dolphin Gull, a neognath
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Subclass: Neornithes
Gadow, 1893[1]
Superorders

Palaeognathae
Neognathae

Modern birds (subclass Neornithes) are the most recent common ancestor of all living birds (class Aves) and all its descendants.

Modern birds are characterised by feathers, a beak with no teeth (ancient birds had teeth), the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. All birds have forelimbs modified as wings and most can fly, with some exceptions including ratites, penguins, and a number of diverse endemic island species. Birds also have unique digestive and respiratory systems that are highly adapted for flight. Some birds, especially corvids and parrots, are among the most intelligent animal species; a number of bird species have been observed manufacturing and using tools, and many social species exhibit cultural transmission of knowledge across generations.

Many species of modern bird undertake long distance annual migrations, and many more perform shorter irregular movements. Birds are social; they communicate using visual signals and through calls and songs, and participate in social behaviours including cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Engagement in extra-pair copulations is common in some species; other species have breeding systems that are polygynous ("many females") or, rarely, polyandrous ("many males"). Eggs are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching.

Contents

Taxonomy

Modern birds are divided into two superorders; the Palaeognathae (tinamous and flightless ratites like ostriches), and the wildly diverse Neognathae, containing all other birds. Depending on the taxonomic viewpoint, the number of species cited varies anywhere from 8,800 to 10,200 known living bird species in the world. It is generally agreed that the Neornithes evolved in the Cretaceous Period and that the split between the Palaeognathae and Neognathae, and then the split between Galloanserae (fowl) and the other Neognathae, occurred before the Cretaceous-Tertiary (K-T) extinction event, but there are different opinions about whether the radiation of the remaining neognathes occurred before or after the extinction of the other dinosaurs.[2] This disagreement is in part caused by a divergence in the evidence, with molecular dating suggesting a Cretaceous radiation and fossil evidence supporting a Tertiary radiation. Attempts made to reconcile the molecular and fossil evidence have proved controversial.[2][3]

The classification of modern birds is a contentious issue. Sibley & Ahlquist's Phylogeny and Classification of Birds (1990) is a landmark work on the classification of birds, although frequently debated and constantly revised. A preponderance of evidence seems to suggest that the modern bird orders constitute accurate taxa. However, scientists are not in agreement as to the relationships between the orders; evidence from modern bird anatomy, fossils and DNA have all been brought to bear on the problem but no strong consensus has emerged. More recently, new fossil and molecular evidence is providing an increasingly clear picture of the evolution of modern bird orders. See also: Sibley-Ahlquist taxonomy and dinosaur classification.

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Classification

 
Aves 

Archaeopteryx


 Pygostylia 

Confuciusornithidae


 Ornithothoraces 

Enantiornithes


 Ornithurae 

Hesperornithiformes


 Neornithes 

Palaeognathae


 Neognathae 

Galloanserae



Neoaves








Basal bird phylogeny showing Neornithes and extinct ancient groups (simplified after Chiappe, 2007[4])
Cladogram showing the most recent classification of Neoaves, based several phylogenetic studies.

This is a list of the taxonomic orders in the subclass Neornithes, or modern birds. The list of birds gives a more detailed summary of these, including families.

Subclass Neornithes

Note: This list is mostly based on the traditional classification (the so-called Clements order) - with the addition of the commonly accepted Galloanserae and Neoaves clades. A radically different classification based on molecular data has been developed (the so-called Sibley-Monroe classification or Sibley-Ahlquist taxonomy). Some of the proposals of the Sibley-Ahlquist taxonomy has influenced taxonomic thinking considerably, with the Galloanserae proving well-supported by recent molecular, fossil and anatomical evidence.[2] With increasingly good evidence, it has become possible to test some major proposals of the Sibley-Ahlquist taxonomy, with favorable results (see for example Charadriiformes, Gruiformes or Caprimulgiformes). However, many proposals of the Sibley-Ahlquist taxonomy are now discarded by most scientists, such as the lumping of many unrelated orders into a greatly enlarged Ciconiiformes.

Phylogeny

Sketch of a Neornithes tree in and around K-T

Basal divergences of modern birds based on the Sibley-Ahlquist taxonomy.

Neornithes  
Palaeognathae 

Struthioniformes



Tinamiformes



 Neognathae 
 

Neoaves


Galloanserae 

Anseriformes


    

Galliformes






Footnotes

  1. ^ System Naturae 2000
  2. ^ a b c Ericson PGP, Anderson CL, Britton T, Elzanowski A, Johansson US, Kallersjo M, Ohlson JI, Parsons TJ, Zuccon D, Mayr G (22 December 2006). "Diversification of Neoaves: integration of molecular sequence data and fossils". Biol Lett 2 (4): 543–547. doi:10.1098/rsbl.2006.0523. PMID 17148284.  
  3. ^ Brown J, Payne B, Mindell D (27 June 2007). "Nuclear DNA does not reconcile 'rocks' and 'clocks' in Neoaves: a comment on Ericson et al.". Biol Lett 3 (3): 1–3. doi:10.1098/rsbl.2006.0611. PMID 17389215.  
  4. ^ Chiappe, Luis M. (2007). Glorified Dinosaurs: The Origin and Early Evolution of Birds. Sydney: University of New South Wales Press. ISBN 978-0-86840-413-4.  

References


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Aves
Subclassis: Carinatae
Infraclassis: Neornithes
Parvclasses: Palaeognathae - Neognathae

Name

Neornithes Gadow, 1893

Vernacular names

Català: Neòrnits
Deutsch: Neuzeitliche Vögel
English: Modern birds
Español: Neornites
Français: Néornithes
עברית: עופות בתראים
Nederlands: nieuwe vogels
日本語: 新鳥下綱
Türkçe: Günümüz kuşları

References

Wikimedia Commons For more multimedia, look at Neornithes on Wikimedia Commons.

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