Adzebill
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The adzebills (genus Aptornis) were two closely related bird species, the North Island Adzebill (Aptornis otidiformis) and the South Island Adzebill (Aptornis defossor) of the extinct family Aptornithidae. The family was endemic to New Zealand and has been placed, by various studies of morphology and DNA, variously close to and far off from the Kagu of New Caledonia, as well as the trumpeters in the order Gruiformes. Its morphological closeness to the kagu may be the result of convergent evolution, although New Zealand's proximity to New Caledonia and shared biological affinities (the two islands are part of the same microcontinent) has led some researchers to suggest they share a common ancestor from Gondwana.
In life the adzebills were massive gruiforms, the size of small moa (with which they were initially confused with on their discovery) with enormous downward pointed bill. They were flightless, having very reduced wings (smaller for their size than those of the dodo, with an uniquely reduced carpometacarpus: Livezey, 1994), and strong legs. The two species varied mostly in size, the North Island Adzebill being the smaller species. Their fossils have been found the drier areas of New Zealand, and only in the lowlands. Richard Owen, who described the two species, speculated that it was an omnivore, and analysis of its bones by stable isotope analysis has seemingly confirmed this. They are thought to have fed on large invertebrates, lizards, tuataras and even small birds.
The adzebills were never as common as the moa, and subjected to the same hunting pressure as the moa and other large birds by the settling Polynesians, they went extinct before the arrival of European explorers. Their remains have been found in archeological sites across New Zealand.
[edit] References
- Livezey, Bradley C. (1994): The carpometacarpus of Apterornis. Notornis 41(1): 51–60. PDF fulltext
- Worthy, Trevor H. (1989): The glossohyal and thyroid bone of Aptornis otidiformes. Notornis 36'(3): 248 PDF fulltext
- Worthy, Trevor H., & Holdaway, Richard N. (2002) The Lost World of the Moa, Indiana University Press:Bloomington, ISBN 0-253-34034-9
[edit] External links
- Reconstruction of A. otidiformis by Alexander Lang
