They are the only ratites known to exhibit this feature, which is also present in several other bird groups, including swans, cranes, and guinea fowl. Excavation of these rings from articulated skeletons has shown that at least two moa genera ( Euryapteryx and Emeus) exhibited tracheal elongation, that is, their trachea were up to 1 m (3 ft) long and formed a large loop within the body cavity. The trachea of moa were supported by many small rings of bone known as tracheal rings. No records survive of what sounds moa made, though some idea of their calls can be gained from fossil evidence. However, Māori rock art depicts moa or moa-like birds (likely geese or adzebills) with necks upright, indicating that moa were more than capable of assuming both neck postures. This has resulted in a reconsideration of the height of larger moa. This would have let them graze on low vegetation, while being able to lift their heads and browse trees when necessary. The spine was attached to the rear of the head rather than the base, indicating the horizontal alignment. Moa skeletons were traditionally reconstructed in an upright position to create impressive height, but analysis of their vertebral articulations indicates that they probably carried their heads forward, in the manner of a kiwi. Description A size comparison between four moa species and a human In 1912, Māori chief Urupeni Pūhara claimed that the moa's traditional name was "te kura" (the red bird). The earliest record of the name was by missionaries William Williams and William Colenso in January 1838 Colenso speculated that the birds may have resembled gigantic fowl. The name was not in common use among the Māori by the time of European contact, likely because the bird it described had been extinct for some time, and traditional stories about it were rare. The word moa is a Polynesian term for domestic fowl. Moa extinction occurred within 100 years of human settlement of New Zealand, primarily due to overhunting. They were the largest terrestrial animals and dominant herbivores in New Zealand's forest, shrubland, and subalpine ecosystems until the arrival of the Māori, and were hunted only by the Haast's eagle. The nine species of moa were the only wingless birds, lacking even the vestigial wings that all other ratites have. However, their closest relatives have been found by genetic studies to be the flighted South American tinamous, once considered to be a sister group to ratites. Moa are traditionally placed in the ratite group. Estimates of the moa population when Polynesians settled New Zealand circa 1300 vary between 58,000 and approximately 2.5 million. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about 3.6 metres (12 ft) in height with neck outstretched, and weighed about 230 kilograms (510 lb) while the smallest, the bush moa ( Anomalopteryx didiformis), was around the size of a turkey. During the Late Pleistocene- Holocene, there were nine species (in six genera). Moa ( order Dinornithiformes) are an extinct group of flightless birds formerly endemic to New Zealand.
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