Palaeognathae

African ostrich ♂ (Struthio camelus )

The Urkiefervögel ( Palaeognathae ) are one of the two sub-classes of birds. You put yourself in the traditional system of the two orders of ratites ( Struthioniformes ) and Tinamou ( TINAMIFORMES ) and together comprise about 60 species in 6 extant families.

Differences they are of the Neukiefervögeln ( Neognathae ) mainly. By another palate structure and a window into the pelvic bone, ilium and ischium between The ratites also have all lost the ability to fly and the Tinamou are no strong flight birds. On the other hand, not all flightless birds also part of the Urkiefervögel: The Penguins, for example, be expected to Neukiefervögeln.

In addition Urkiefervögel have a slightly poorer color discrimination than Neukiefervögel.

System

The Urkiefervögel be viewed in more recent phylogenetic studies as a monophyletic group. You are inside the still living ( extant ) birds that consistently rank among the Neornithes, the sister group of all other than Neukiefervögel ( Neognathae ) summarized kinship groups ( taxa ). The order of ratites ( Struthioniformes ) is paraphyletic, however, that is, although it has a common ancestral form, but the ratites not include all sub- groups, which are derived from this ancestral form. Emu, cassowaries, kiwis, consisting of dead moa and rheas are in fact more closely with the airworthy Steißhühnern ( TINAMIFORMES ) used as the ostriches ( Struthioniformes narrow sense ), who first cleaved from the emanating from the common progenitor line. Indisputable is the close relationship of emu and cassowary, which are summarized in modern classification systems as an order Casuariiformes. The closest relatives of this group are the Kiwis. Umklar remains who is the nearest relative of the South American Tinamou, which is also South American rheas, the Moa or the clade of emu, cassowaries and kiwis.

Cladogram:

Ostriches ( Struthioniformes )

Moa ( Dinornithiformes ) †

Tinamou ( TINAMIFORMES )

Rheas ( RHEIFORMES )

Emus ( Dromaiidae )

Cassowaries ( Casuariidae )

Kiwis ( Apterygiformes )

The position of the extinct taxa Lithornithiformes and elephant birds ( Aepyornithiformes ) is uncertain.