What is the distinctive feature of birds of the class 'ratites'?
"evolved into some basic lineages by the end of the Cretaceous (see ""Vegavis""). The Neornithes are split into the paleognaths and neognaths. The paleognaths include the tinamous (found only in Central and South America) and the ratites, which nowadays are found almost exclusively on the Southern Hemisphere. The ratites are large flightless birds, and include ostriches, rheas, cassowaries, kiwis and emus. A few scientists propose that the ratites represent an artificial grouping of birds which have independently lost the ability to fly in a number of unrelated lineages. In any case, the available data regarding their evolution is still very"
"term ""ratite"" is from the Latin word for raft, ""ratis"", because they possess a flat breastbone, or sternum, shaped like a raft. This characteristic sternum differs from that in flighted birds, where the pectoral musculature is disproportionately large to provide the power for wingbeats and the sternum develops a prominent keel, or carina sterni to anchor these muscles. The clavicles do not fuse into a furcula. Instead, if present at all, each is splint-like and lies along the medial border of the coracoid, attached there by a coraco–clavicular ligament. There is an obtuse angle between the scapula and coracoid, and"
"Ratite A ratite is any of a diverse group of flightless and mostly large and long-legged birds of the infraclass Palaeognathae. Kiwi, however, are relatively much smaller and shorter-legged, as well as being the only nocturnal ratites. The systematics of and relationships within the paleognath clade have been in flux. Previously, all the flightless members had been assigned to the order Struthioniformes, which is more recently regarded as containing only the ostrich. The modern bird superorder Palaeognathae consists of ratites and flighted Neotropic tinamous (compare to Neognathae). Unlike other flightless birds, the ratites have no keel on their sternum –"
"seq.). Ratite A ratite is any of a diverse group of flightless and mostly large and long-legged birds of the infraclass Palaeognathae. Kiwi, however, are relatively much smaller and shorter-legged, as well as being the only nocturnal ratites. The systematics of and relationships within the paleognath clade have been in flux. Previously, all the flightless members had been assigned to the order Struthioniformes, which is more recently regarded as containing only the ostrich. The modern bird superorder Palaeognathae consists of ratites and flighted Neotropic tinamous (compare to Neognathae). Unlike other flightless birds, the ratites have no keel on their sternum"
"more efficient use of energy in adulthood. The name ""ratite"" refers to their flat sternum that is distinct from the typical sternum of flighted birds because it lacks the keel. This structure is the place where flight muscles attach and thus allow for powered flight. However, ratite anatomy presents other primitive characters meant for flight, such as the fusion of wing elements, a cerebellar structure, the presence of a pygostyle for tail feathers, and an alula on the wing. These morphological traits suggest some affinities to volant groups. Palaeognathes were one of the first colonizers of novel niches and were"
"such as the ostrich are farmed and sometimes even kept as pets. Ratites play a large role in human culture; they are farmed, eaten, raced, protected, and kept in zoos. Footnotes Sources Palaeognathae Palaeognathae, or paleognaths, is one of the two living clades of birds – the other being Neognathae. Together, these two clades form the clade Neornithes. Palaeognathae contains five extant branches of flightless lineages (plus two extinct clades), termed ratites, and one flying lineage, the Neotropic tinamous. There are 47 species of tinamous, 5 of kiwis (""Apteryx""), 3 of cassowaries (""Casuarius""), 1 of emus (""Dromaius"") (another became extinct"
"ratites such as emus, ostriches, cassowaries, and kiwis, along with the extinct forms: moas and elephant birds. There are five subspecies of the greater rhea; their ranges meet around the Tropic of Capricorn: Main subspecific differences are the extent of the black coloring of the throat and the height. However, subspecies of the greater rhea differ so little across their range that, without knowledge of the place of origin, it is essentially impossible to identify captive birds by subspecies. The adults have an average weight of and often measure long from beak to tail; they usually stand about tall, with"
"""raft"", referring to the flatness of the sternum). The difficulty with this scheme phylogenetically was that some flightless birds, without strong keels, are descended directly from ordinary flying birds possessing one. Examples include the kakapo, a flightless parrot, and the dodo, a columbiform (the pigeon family). None of these birds is a ratite. Thus, this supposedly distinctive feature was easy to use, but had nothing to do with actual phylogenetic relationship. Beginning in the 1980s, Carinatae was given several phylogenetic definitions. The first was as a node-based clade uniting ""Ichthyornis"" with modern birds. However, in many analyses, this definition would"
"Unlike other ratites, tinamous can fly, although in general they are not strong fliers. All ratites evolved from prehistoric flying birds, and tinamous are the closest living relative of these birds. Isidore Geoffroy Saint-Hilaire first identified the elegant crested tinamou from a specimen from South America, in 1832. The elegant-crested tinamou averages long. The species is a dark or yellowish brown partridge-like bird with a short tail and wings, two white stripes on each side of its face and a long crest with an upward pointed tip. The feet have no hind toes and the bluish or greyish legs are"
"species richness and no mammalian predators, the need for large, powerful flight muscles that make for a quick escape decreases. Moreover, raptor species tend to become generalist predators on islands with low species richness as opposed to specializing in the predation of birds. An increase in leg size compensates for a reduction in wing length in insular birds that have not lost flight by providing a longer lever to increase force generated during the thrust that initiates takeoff. Ratites in general have many physical characteristics in common, which are often not shared by the family Tinamidae, or tinamous. First, the"
"this specimen to ""Struthiomimus altus""; he partly based his reconstruction of ""S. altus"" on the skull of the specimen. The remainder of the skeleton was not described until 2016. In 2016, the type species ""Rativates evadens"" was named and described by Bradley McFeeters, Michael J. Ryan, Claudia Schröder-Adams and Thomas M. Cullen. The generic name is derived from the Latin ""ratis"", ""raft"", in reference to the bird group ratites, and ""vates"", ""seer"", as the ornithomimids, as it were, foretold the future existence of the ratites they resembled. The specific name ""evadens"" means ""evading"" in Latin, referring to the ability of"
"as near passerines. Feduccia defined the clade Neognathia as birds whose palatal mobility increased due to the following modifications (Feduccia 1980, 1996): Neognathae cladogram of modern bird relationships based on Prum, R.O. ""et al"". (2015) with some clade names after Yury, T. et al. (2013) and Kimball et al. 2013. Neognathae Neognaths (Neognathae) are birds within the subclass Neornithes of the class Aves. The Neognathae include virtually all living birds; exceptions being their sister taxon (Palaeognathae), which contains the tinamous and the flightless ratites. There are nearly 10,000 species of neognaths. The earliest fossils are known from the very end"
"invisible under the bristly, hair-like, two-branched feathers. While most adult birds have bones with hollow insides to minimise weight and make flight practicable, kiwi have marrow, like mammals and the young of other birds. With no constraints on weight due to flight requirements, brown kiwi females carry and lay a single egg that may weigh as much as . Like most other ratites, they have no uropygial gland (preen gland). Their bill is long, pliable and sensitive to touch, and their eyes have a reduced pecten. Their feathers lack barbules and aftershafts, and they have large vibrissae around the gape."
"the similarities between the ratite orders are partly due to convergent evolution, and that the Palaeognathae are monophyletic, but the ratites are not. Beginning in 2010, DNA analysis studies have shown that tinamous are the sister group to extinct moa of New Zealand. In the history of biology there have been many competing taxonomies of the birds now included in the Palaeognathae. The topic has been studied by Dubois (1891), Sharpe (1891), Shufeldt (1904), Sibley and Ahlquist (1972, 1981) and Cracraft (1981). Merrem (1813) is often credited with classifying the paleognathes together, and he coined the taxon ""Ratitae"" (see above)."
"ranging in height from and weight . They have shaggy brown feathers. Tinamous range in size from and weigh . Many of the larger ratite birds have extremely long legs and the largest living bird, the ostrich, can run at speeds over 35 mph (60 km/h). Emus have long, strong legs and can run up to . Cassowaries and rheas show a similar likeness in agility and some extinct forms may have reached speeds of 45 mph (75 km/h). Today, the ratites are largely restricted to the Southern Hemisphere, though across the Cenozoic they were also present in Europe, North"
"Rhea (bird) The rheas () are large ratites (flightless birds without a keel on their sternum bone) in the order Rheiformes, native to South America, distantly related to the ostrich and emu. Most taxonomic authorities recognize two extant species: the greater or American rhea (""Rhea americana"") and the lesser or Darwin's rhea (""Rhea pennata""). The IUCN lists the puna rhea (""Rhea tarapacensis"") as a separate species. The IUCN currently rates the greater and puna rheas as near-threatened in their native ranges, while Darwin's rhea is of least concern. In addition, a feral population of the greater rhea in Germany appears"
"hence the name from the Latin ""ratis"" (raft, a vessel which has no keel). Without this to anchor their wing muscles, they could not fly even if they were to develop suitable wings. Recent research has indicated that ratites are a paraphyletic group; tinamous fall within them, and are the sister group of the extinct moa. This implies that flightlessness is a trait that evolved independently multiple times in different ratite lineages. Most parts of the former supercontinent Gondwana have ratites, or did have until the fairly recent past. So did Europe in the Paleocene and Eocene, from where the"
"birds. The pelvis has an open ilio–ischiatic fenestra that incises the posterior edge between the ilium and ischium, as in all paleognathes. Tinamous have no true pygostyle, their caudal vertebrae remain unfused, as in ratites. Tinamou feathers look like those of volant birds in that they have a rachis and two vanes. The structure of tinamou feathers is unique, however, in that they have barbs that remain joined at their tips. Thus the parallel barbs are separated only by slits between them. Tinamous have uropygial glands. Ratite birds are strictly flightless and their anatomy reflects specializations for terrestrial life. The"
"19 loci in 169 species. It recovered evidence that the paleognathes are one natural group (monophyletic), and that their divergence from other birds is the oldest divergence of any extant bird groups. It also placed the tinamous within the ratites, more derived than ostriches, or rheas and as a sister group to emus and kiwis, and this makes ratites paraphyletic. A related study addressed the issue of paleognath phylogeny exclusively. It used molecular analysis and looked at twenty unlinked nuclear genes. This study concluded that there were at least three events of flightlessness that produced the different ratite orders, that"
"Neognathae Neognaths (Neognathae) are birds within the subclass Neornithes of the class Aves. The Neognathae include virtually all living birds; exceptions being their sister taxon (Palaeognathae), which contains the tinamous and the flightless ratites. There are nearly 10,000 species of neognaths. The earliest fossils are known from the very end of the Cretaceous but molecular clocks suggest that neognaths originated sometime in the first half of the Late Cretaceous about 90 million year ago. Since then, they have undergone adaptive radiation producing the diversity of form, function, and behavior that we see today. It includes the order Passeriformes (perching birds),"
"a thin sheet of nasal bones is attached to the skull at the nasofrontal hinge, which gives mobility to the upper mandible, allowing it to move upwards and downwards. The base of the upper mandible, or the roof when seen from the mouth, is the palate, the structure of which differs greatly in the ratites. Here, the vomer is large and connects with premaxillae and maxillopalatine bones in a condition termed as a ""paleognathous palate"". All other extant birds have a narrow forked vomer that does not connect with other bones and is then termed as neognathous. The shape of"
"named from its harsh cry, in Vulgar Latin *""rascula"", from Latin ""rādere"" ('to scrape'). The rails are a family of small to medium-sized, ground-living birds. They vary in length from and in weight from . Some species have long necks and in many cases are laterally compressed. The bill is the most variable feature within the family. In some species, it is longer than the head (like the clapper rail of the Americas); in others, it may be short and wide (as in the coots), or massive (as in the purple gallinules). A few coots and gallinules have a frontal"
"Rail (bird) The rails, or Rallidae, are a large cosmopolitan family of small- to medium-sized, ground-living birds. The family exhibits considerable diversity and includes the crakes, coots, and gallinules. Many species are associated with wetlands, although the family is found in every terrestrial habitat except dry deserts, polar regions, and alpine areas above the snow line. Members of the Rallidae occur on every continent except Antarctica. Numerous island species are known. The most common rail habitats are marshland and dense forest. They are especially fond of dense vegetation. ""Rail"" is derived from French ""râle"", from Old French ""rasle"". It is"
"rhea, large fast-running birds of the Pampas. The larger American rhea grows to about tall and usually weighs . The smallest ratites are the five species of kiwi from New Zealand. Kiwi are chicken-sized, shy, and nocturnal. They nest in deep burrows and use a highly developed sense of smell to find small insects and grubs in the soil. Kiwi are notable for laying eggs that are very large in relation to their body size. A kiwi egg may equal 15 to 20 percent of the body mass of a female kiwi. The smallest species of kiwi is the little"
"Carinatae Carinatae is the group of all birds and their extinct relatives to possess a keel, or ""carina"", on the underside of the breastbone used to anchor large flight muscles. Traditionally, Carinatae were defined as all birds whose sternum (breast bone) has a keel (""carina""). The keel is a strong median ridge running down the length of the sternum. This is an important area for the attachment of flight muscles. Thus, all flying birds have a pronounced keel. Ratites, all of which are flightless, lack a strong keel. Thus, living birds were divided into carinatae (keeled) and ratites (from ""ratis"","
"to carry off large primates; today, lemurs still retain a fear of aerial predators such as these. Another might be the perception of ratites retaining neotenic features and thus being mistaken for enormous chicks of a presumably more massive bird. The ancient Malagasy name for the bird is vorompatra, meaning ""bird of the Ampatres"". The Ampatres are today known as the Androy region of southern Madagascar. Like the ostrich, rhea, cassowary, emu, kiwi and extinct moa, ""Mullerornis"" and ""Aepyornis"" were ratites; they could not fly, and their breast bones had no keel. Because Madagascar and Africa separated before the ratite"
"ratite evolution than the northern ones, often to irrational extremes. Feduccia (1995) emphasized the extinction event at the Cretaceous-Paleogene boundary as the probable engine of diversification in the Neornithes, picturing only one or very few lineages of birds surviving the end of the Cretaceous. He also noted that birds around the world had developed ratite-like anatomies when they became flightless, and saw the affinities of modern ratites, especially kiwis, as ambiguous. In this emphasis on the Cenozoic, rather than Cretaceous period, as the time of basal divergences between neornithines, he follows Olson. Houde demonstrated that the Lithornithiformes, a group of"
"Tinamou Tinamous form an order of birds (Tinamiformes), comprising a single family (Tinamidae) with two distinct subfamilies, containing 47 species found in Mexico, Central America, and South America. The word ""tinamou"" comes from the Galibi term for these birds, ""tinamu"". Tinamous have traditionally been regarded as the sister group of the flightless ratites, but recent work places them well within the ratite radiation, implying basal ratites could fly. Tinamous first appear in the fossil record in the Miocene epoch. They are generally sedentary, ground-dwelling and, though not flightless, when possible avoid flight in favour of hiding or running away from"
"in some individuals, also on the third). Ostriches differ from other paleognathes in that they have a reduced vomer bone of the skull. Emus are in height and weigh . They have short wings and the adults have brown feathers. Rheas are and weigh . Their feathers are gray or spotted brown and white. They have large wings but no tail feathers. They have no clavicles. Cassowaries are in height and weigh . They have rudimentary wings with black feathers and six stiff, porcupine-like, quills in the place of their primary and secondary feathers. Kiwis are the smallest of ratites,"
"Patagonian tinamou The Patagonian tinamou (""Tinamotis ingoufi"") also known as Ingouf’s tinamou is a member of the most ancient group of bird families, the tinamous. This species is native to southern South America The Patagonian tinamou is a monotypic species. All tinamou are from the family Tinamidae, and in the larger scheme are also ratites. Unlike other ratites, tinamous can fly, although in general, they are not strong fliers. All ratites evolved from prehistoric flying birds, and tinamous are the closest living relative of these birds. The Patagonian tinamou is approximately in length. Its upper parts are grey spotted with"
"Palaeognathae Palaeognathae, or paleognaths, is one of the two living clades of birds – the other being Neognathae. Together, these two clades form the clade Neornithes. Palaeognathae contains five extant branches of flightless lineages (plus two extinct clades), termed ratites, and one flying lineage, the Neotropic tinamous. There are 47 species of tinamous, 5 of kiwis (""Apteryx""), 3 of cassowaries (""Casuarius""), 1 of emus (""Dromaius"") (another became extinct in historic times), 2 of rheas and 2 of ostrich. Recent research has indicated that paleognaths are monophyletic but the traditional taxonomic split between flightless and flighted forms is incorrect; tinamous are"
"mass of flight muscles; the absence of predators (particularly mammalian) and a reduced need for dispersal are factors that allow this feature to develop in island birds. J.R. Forster stated the Tahiti rail was long, which is small for a species of ""Gallirallus"". Its colouration was also striking and unusual for a rail, and it was described as being an attractive bird. The upper parts were black with white dots and bands (also referred to as spots and bars), and the underparts, throat, and eyebrow-like supercilium were white. The nape (or hind neck) was ferruginous (rust-coloured), the breast was grey,"
"like a ratite's. It has unique characteristics quite unlike the sternum of any other bird (though vaguely convergent to that of the modern hoatzin), making it easily identifiable. Both ""P. antiqua"" and ""P. gigantea"" were clearly flightless, being large birds with far too short forelimbs and keels, the former in particular having highly reduced metacarpals, though ""P. wetmorei"" might have still been capable of limited flight. ""Paracrax gigantea"" in particular is a very large bird, reaching estimated heights of over , making it among the largest of bathornithids and among the tallest animals in its environment. Like most Cariamiformes, including"