ratite


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ratite

ratite (rătˈīt), common and general term for a variety of flightless birds characterized by a flat, raftlike sternum rather than the keeled sternum, designed to support flight muscles, typical of most birds. Once used more technically, ratite, or Ratitae, is today but a loose covering term for a number of bird orders whose members possess such a breast shape. It is generally recognized, however, that the common morphology shared by these assorted birds is the product of a shared adaptation to ground living rather than of a common evolutionary descent. While ratites were formerly thought to be ancestral to the carinates, or flying birds, they are now believed to be forms that have lost adaptation for flight. Indeed, they resemble permanent overgrown chicks with short, stubby wings and soft rather than stiff-vaned flight feathers. This condition, in which animals reach adult size and maturity while maintaining an infantile appearance, is called neoteny. In their own environment, however, the ratites are by no means inferior to other birds. With their strong, heavy legs and reduced toes, they are powerful runners, and their heavy, solid bones are sturdier than the hollow bones of flying birds. The ratites include the Afro-Asian ostriches (order Struthioniformes) and their South American counterparts the rheas (Rheiformes) as well as a number of orders now or recently native to Australia, New Zealand, and New Guinea—the emus and cassowaries (Casuariiformes); the kiwis (Apterygiformes); the extinct moas (Dinornithiformes); the Madagascan elephant birds (Aepyornithiformes); and several other extinct orders. The small, tropical New World tinamou (order Tinamiformes) has a keeled sternum and can fly, but shares some features with the ratites, such as the possession of a specialized bony palate. The flightless penguins are not ratites, since they have neither bony palate nor flat breastbone. In addition, their wings are powerful swim fins, and their chest muscles and sternum are as developed as those of any flying bird. The orders of ratites are classified in the phylum Chordata, subphylum Vertebrata, class Aves.
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References in periodicals archive ?
As observed in birds (Banks, 1991; Rupley, 1999; Benez, 2001), ratites (Huchzermeyer, 2000; Blue-McLendon and Green, 2010), carijo hawks (Santos, 2001) and rheas (Fortes et al., 2009), eosinophils found in rheas in the present study may also have bilobular or trilobular nucleus.
As argued above, one of the advantages of ratite eggshell as an archaeological dating material, especially for cave sites, is that it is extremely unlikely to have entered the deposit other than through direct human activity.
Five years ago, ratites (emus, ostrich, rheas) were all selling at high prices.
Ratites (rah-tit) are a group of large flightless birds.
El avestruz pertenece al grupo de los Ratite del que se conocen varios Ordenes: entre ellos el Orden Struthioniformes, al cual pertenece el avestruz que habita en desiertos y sabanas de Africa y la peninsula Arabiga.
Saying that, however, I've certainly seen no evidence of ratite relations occurring yet - though the stags have been displaying and strutting around beautifully for weeks now.
Joe Haid, editor of several magazines about the ratite industry, says emu oil is an "inert ingredient" in sunscreens, shampoos, perfumes, and lotions.
Like other ratite birds including the ostrich, cassowary, rhea and kiwi, this bird can neither fly nor run.
The epididymis and its the development in ratite birds (Ostrich, Emu, Rhea).
The researchers conclude that, while clearly members of the ratite group, moas diverged from other ratites early in their evolution.
The phylogeny and relationships of ratite birds as indicated by DNA-DNA hybridization.