Bird taxonomyBirds are categorised as a biological class, Aves. The earliest known species of this class is Archaeopteryx lithographica, from the Late Jurassic period. According to the most recent consensus, Aves and a sister group, the order Crocodilia, together form a group of unnamed rank, the Archosauria.
Phylogenetically, Aves is usually defined as all descendants of the most recent common ancestor of modern birds (or of a specific modern bird species like Passer domesticus), and Archaeopteryx. Modern phylogenies place birds in the dinosaur clade Theropoda.
Modern birds are divided into two superorders, the Paleognathae (mostly flightless birds like ostriches), and the wildly diverse Neognathae, containing all other birds.
Relationships between bird orders according the Sibley-Ahlquist taxonomy. "Galloanseri" is now considered a superorder Galloanserae.
This is a list of the taxonomic orders in the class Aves.
Paleognathae:
Neognathae:
Note: This is the traditional classification (the so-called Clements order). A more recent, radically different classification based on molecular data has been developed (the so-called Sibley-Monroe classification or Sibley-Ahlquist taxonomy). This has influenced taxonomical thinking considerably, with the Galloanserae proving well-supported by recent molecular, fossil and anatomical evidence[citation needed]. With increasingly good evidence, it has become possible by 2006 to test the major proposals of the Sibley-Ahlquist taxonomy. The results are often nothing short of astounding, see e.g. Charadriiformes or Caprimulgiformes.
A wide variety of bird groups became extinct during the Mesozoic era and left no modern descendants. These include the Order Archaeopterygiformes, Order Confuciusornithiformes, toothed seabirds like the Hesperornithiformes and Ichthyornithes, and the diverse Subclass Enantiornithes ("opposite birds").
Shoebill, Balaeniceps rex
This guide is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.
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