Neornithes


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Neornithes

The subclass of Aves that contains all of the known birds other than those placed in the Archaeornithes. Comprising more than 30 orders, both fossil and living, its members are characterized by a bony, keeled sternum with fully developed powers of flapping flight (secondarily lost in a number of groups); a short tail with the caudal vertebrae fused into a single platelike pygostyle to which all tail feathers attach; a large fused pelvic girdle with a reversed pubis which is fused to a large synsacrum; and a large brain and eyes contained within a fused braincase. The jaws are specialized into a beak covered with a horny rhamphotheca; the upper jaw is kinetic, being either prokinetic or rhynchokinetic. Prokinesis refers to a bending zone at the base of the upper jaw, and rhynchokinesis to one within the upper jaw. A few fossil groups still possess teeth, but most fossil and all Recent birds have lost teeth. See Archaeornithes

The Neornithes contains two superorders, the Odontognathae and the Neognathae. The Odontognathae, alternately known as the Odontornithes, may be an artificial group. Its members, which include the Cretaceous fossil orders Hesperornithiformes and Ichthyornithiformes, are united only by the presence of teeth in all species. The Neognathae contains the remaining modern birds, which have lost the teeth, and includes 26 orders. See Aves

Neornithes

[nē′ȯr·nə‚thēz]
(vertebrate zoology)
A subclass of the class Aves containing all known birds except the fossil Archaeopteryx.
References in periodicals archive ?
Within Neornithes, the affilliation of Lamarqueavis to any particular extant or extinct avian clade is uncertain.
In Neornithes, procoracoid morphology is highly variable, although a procoracoidal process appears to be invariably absent in basal clades (i.
2006), including Neornithes (and also Cimolopteryx sensu stricto and Ceramornis) the humeral articular surface is ovoidal in contour and shows all margins strongly convex.
Moreover, Limenavis is considered by CLARKE & CHIAPPE (2001) as a basal Carinatae bird, whereas the specimens here described belong to a more derived bird nested within the lesser inclusive clade Neornithes.
MML 208 resembles Neornithes in the humeral articular surface not extended sternally beyond the omal margin of the scapular cotyla (HOPE, 2002).
Because of its fragmentary nature, and contradictory combination of traits, MML 208 could not be located more precisely within Neornithes, and is here considered as cf.
Cimolopterygidae may be considered as the most numerically abundant and specifically diverse group of stem Neornithes known from the Mesozoic (HOPE, 2002).
Some authors, based mainly on molecular data have suggested that birds were not severally affected by the K/T extinction event, and that most clades of Neornithes were well in progress along most of the Late Cretaceous (see detailed discussion in FEDUCCIA, 2003; SLACK et al.
2006), on the basis on fossil record and phylogenetic bracket, proposed that Neornithes may have originated in water environments, and that probably aquatic niches played an important role in Ornithurine evolution.
In this way, this author argued that available fossils indicated that Ornithurae and Neornithes may have its origin in Laurasia, because the majority of gondwanan mesozoic birds are Enantiornithes or very basal stem-Ornithurae.