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 Various ratite birds
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Struthionidae (ostriches) |
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Elephant birds are an extinct family of Flightless Birds comprising the genera Aepyornis and Mullerornis. The Moa were ten species (in six genera of flightless Birds endemic to New Zealand. KIWI (1029 FM, "Radio Lobo" is a commercial Radio station located in McFarland California, broadcasting to the Bakersfield California Flightless birds are birds which lack the ability to fly relying instead on their ability to run or swim and are thought to have evolved from their flying ancestors Gondwana (ɡɒnˈdwɑːnə originally Gondwanaland) was a southern Supercontinent that existed about 500 to 200 Ma ago Unlike other flightless birds, the ratites have no keel on their sternum - hence their name which comes from the Latin (ratis) for raft. A keel in Bird anatomy is an extension of the Sternum which runs axially along the midline of the sternum and extends outward perpendicular to the plane of the The sternum (from Greek στέρνον sternon, "chest" or breastbone) is a long flat Bone located in the center of the thorax (chest A raft is any flat floating structure for travel over water It is the most basic of Boat design characterized by the absence of a hull. Without this to anchor their wing muscles they could not fly even if they were to develop suitable wings.
Most parts of the former Gondwana have ratites, or have had until the fairly recent past. Gondwana (ɡɒnˈdwɑːnə originally Gondwanaland) was a southern Supercontinent that existed about 500 to 200 Ma ago Their closest living relatives are the tinamous of South America. The tinamous are one of the most ancient groups of Bird, members of a South American Bird family of about 47 species in 9 genera [1][2]
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Living forms
The African Ostrich is the largest living ratite. The Ostrich ( Struthio camelus) is a large Flightless bird native to Africa (and formerly the Middle East) A large member of this species can be nearly 3 meters (9. 9 feet) tall, weigh as much as 159 kg (350 lb), and can outrun a horse.
Of the living species, the Australian emu is next in size, reaching up to 2 m (6. The Emu ( Dromaius novaehollandiae, is the largest Bird native to Australia and the only extant member of the Genus 6 feet) tall and about 60 kg (130 lb). Like the ostrich, it is a fast-running, powerful bird of the open plains and woodlands.
Also native to Australia and the islands to the north are the three species of cassowary. Cassowaries ( Genus Casuarius) are very large flightless Birds native to the Tropical forests of New Guinea and Shorter than an emu and very solidly built, cassowaries prefer thickly vegetated tropical forest. They can be very dangerous when surprised or cornered. In New Guinea, cassowary eggs are brought back to villages and the chicks raised for eating as a much-prized delicacy, despite (or perhaps because of) the risk they pose to life and limb. New Guinea, located just north of Australia, is the world's second largest island, having become separated from the Australian mainland when the area now known
South America has two species of rhea, mid-sized, fast-running birds of the Pampas. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a The rheas are species of flightless Ratite Birds in the genus Rhea, native to South America. Laguna de Gomezjpg|thumb|left|240px|Lake Gomez near Junín in the heart of the Pampas grain belt The larger American rhea grows to about 1. 5 meters(5 feet) tall and usually weighs 20 to 25 kg (44 to 55 lb). (South America also has 73 species of the small and ground-dwelling but not flightless tinamou family, which is distantly related to the ratite group. The tinamous are one of the most ancient groups of Bird, members of a South American Bird family of about 47 species in 9 genera )
The smallest ratites are the five species of kiwi from New Zealand. KIWI (1029 FM, "Radio Lobo" is a commercial Radio station located in McFarland California, broadcasting to the Bakersfield California Kiwi are chicken-sized, shy, and nocturnal. The chicken ( Gallus gallus, sometimes G gallus domesticus) is a domesticated Fowl which is traditionally believed to have descended from 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 Spotted Kiwi, at 1. The Little Spotted Kiwi ( Apteryx owenii) is a small species of Kiwi originally from South Island (what is known is they used to live near 2 kg (2. 7 lb) and 40 cm (16 inches).
Extinct forms
Aepyornis, the "elephant bird" of Madagascar, was the largest bird ever known. Elephant birds are an extinct family of Flightless Birds comprising the genera Aepyornis and Mullerornis. Madagascar, or Republic of Madagascar (older name Malagasy Republic) is an Island nation in the Indian Ocean off the southeastern Although shorter than the tallest moa, a large Aepyornis could weigh over 450 kg (1,000 lb) and stand up to 3 meters (10 feet) tall. The Moa were ten species (in six genera of flightless Birds endemic to New Zealand.
Moa - at least eleven species in New Zealand, ranging from turkey-sized, to the Giant Moa Dinornis giganteus with a height of 3. The Moa were ten species (in six genera of flightless Birds endemic to New Zealand. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island The giant moa ( Dinornis) is an extinct genus of Ratite birds belonging to the Moa family 3 meters (11 feet) and weighing about 250 kg (550 lb)[1]. Extinct by 1500 due to hunting by Māori settlers, who arrived around 1000, although at least one species may have survived past this date and was even possibly seen by early European settlers. This article discusses the Māori people of New Zealand For their language see Māori language, and for other meanings see Māori (disambiguation.
In addition, eggshell fragments similar to those of Aepyornis were found on the Canary Islands. The Canary Islands ( English pronunciation kəˈnæriː ˈaɪləndz Spanish: Islas Canarias, ˈizlas kaˈnarjas are a Spanish The fragments apparently date to the Middle or Late Miocene, and no satisfying theory has been proposed as to how they got there due to uncertainties about whether these islands were ever connected to the mainland. The Miocene is a geological epoch of the Neogene period and extends from about 23
Evolution and systematics
There are two taxonomic approaches to ratite classification: the one applied here combines the groups as families in the order Struthioniformes, while the other supposes that the lineages evolved mostly independently and thus elevates the families to order rank (e. Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos In Biological classification, family ( Latin This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used g. Rheiformes, Casuariformes etc. ).
Numerous studies based on morphology, immunology and DNA sequencing indicate that ratites are monophyletic. [1] The traditional account of ratite evolution has the group emerging in flightless form in Gondwana in the Cretaceous, then evolving in their separate directions as the continents drifted apart. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of However, recent analysis of genetic variation between the ratites conflicts with this: DNA analysis appears to show that the ratites diverged from one another too recently to share a common Gondwanian ancestor. Also, the Middle Eocene fossil "proto-ostrich" Palaeotis from Central Europe may imply that the "out-of-Gondwana" hypothesis is wrong. Palaeotis is a Palaeognath bird from the Eocene epoch. Originally it was thought to be a bustard hence its name ( Palaeotis means ancient bustard
A comparative study of the full mitochondrial DNA sequences of living ratites plus two moas places moas in the basal position, followed by rheas, followed by ostriches, followed by kiwis, with emus and cassowaries being closest relatives. [1] Another study has reversed the relative positions of moas and rheas, and indicated that elephant birds are not close relatives of ostriches or other ratites. [2] What these studies have in common is branching dates that imply that while the ancestors of moas may have been present in New Zealand since it split off from other parts of Gondwana, the ancestors of kiwis appear to have somehow dispersed there from Australia more recently, perhaps via a land bridge or by island-hopping. Similarly, ostriches seem to have arrived in Africa by some route after it detached from South America. Other aspects of ratite paleobiogeography were found to be consistent with the vicariance (plate tectonic split-up of Gondwana) hypothesis. Biogeography is the study of the distribution of Biodiversity over Space and Time. Allopatric speciation, also known as geographic Speciation, is the phenomenon whereby biological populations are physically isolated by an extrinsic barrier Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere
References and Notes
- ^ a b c Haddrath, O. ; Baker, A. J. (2001). "Complete mitochondrial DNA genome sequences of extinct birds: ratite phylogenetics and the vicariance biogeography hypothesis". Proc. R. Soc. Lond. B 268: 939-945. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ a b Cooper, A. ; Lalueza-Fox, C. ; Anderson, S. ; Rambaut, A. ; Austin, J; Ward, R. (2001-02-08). "Complete mitochondrial genome sequences of two extinct moas clarify ratite evolution". Nature 409: 704-707.
Gallery of Living Species
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Dictionary
ratite
-noun
- The order of Struthioniformes, a diverse group of large running, flightless birds, mostly extinct, but including the cassowary, elephant bird, emu, kiwi, moa, ostrich, rhea and tinamou
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