Moa nalos

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Moa nalos
Kauai Moa Nalo (Chelychelynechen quassus) reconstruction based on beak shape and relationship

Kauai Moa Nalo ( Chelychelynechen quassus )
reconstruction based on beak shape and relationship

Systematics
Class : Birds (aves)
Order : Goose birds (Anseriformes)
Family : Duck birds (Anatidae)
incertae sedis
Tribe : Moa nalos
Scientific name
Thambetochenini
Livezey , 1996

The Moa Nalos were flightless endemic duck birds (Anatidae) of the Hawaiian Islands.

The word Moa-Nalo is made up of Hawaiian "Moa" for poultry and "nalo", which means lost or forgotten.

Way of life

Before humans arrived in the Hawaiian archipelago , the moa nalos were the archipelago's largest herbivores, occupying an ecological niche similar to that of the various giant tortoise species in the Mascarene Islands , the Seychelles, and the Galapagos Islands . They specialized in digesting plant fibers in the back of the colon .

The species Kauai Moa-Nalo ( Chelychelynechen quassus ) had a high, broad beak , which - similar to a turtle's mouth - was used to graze herbs . The longer, downwardly curved, pointed beaks of the other Moa Nalo species had bony pseudo- teeth to enable them to eat grass and twigs. As a defense against the Moa Nalos as well as against the Hawaiian geese (Nēnēs), for example, the plant genus Cyanea, which belongs to the Lobelioideae ( lobelia plants ), has developed spines and leaves that look different ( heterophylly ).

description

The shoulder girdle and the wings were extremely reduced, even more so than in the giant geese of the genus Cnemiornis on New Zealand's South Island . The sternum ridge was also completely missing. The rear legs were accordingly stronger. Their bones are all very large and strong. The clavicle and raven bones are clearly regressed. In some of the species, the raven bone is either fused with the shoulder blade, with which it forms a right angle, or with the sternum. The wishbone is very weak and may be absent from a population. The wing bones are very small compared to the size of the birds and are often significantly deformed. The ulna and radius are often fused into a single bone, the gap between the two bone parts of the carpometacarpus is often closed and this bone is often fused with the first phalanx of the big finger. The beaks are large, strong and unusually shaped.

External system

Because of the extreme regression of the wings and the shoulder girdle, a systematically correct classification of the species is difficult. In 1991, based on the shape of the syrinx, Olson and James assumed that the Moa nalos must be more ducks (Anatinae) than geese (Anserinae). Livecey came to the conclusion in 1996 by examining the skeleton that they were a sister group of the geese and swans. In the meantime, in 1999 it was established by genetic tests that their closest living relatives are the swimming ducks (Anantini).

Distribution history

The Moa Nalos probably split off from the other swimming ducks (Anantini) over three million years ago . This means that they probably reached Kauaʻi and / or Oʻahu at that time and later a species that was not yet completely flightless emigrated to Molokai , from where they could migrate on foot to the islands of Lanai and Maui in the Pleistocene , which at that time with Molokai formed a coherent island. It was never able to colonize Hawaii because it was completely incapable of flight when this island was formed.

They were exterminated by the Polynesian settlers around 1,600 years ago as one of the first bird species on the archipelago .

species

  • The Kauai Moa Nalo ( Chelychelynechen quassus Olson & James, 1991) lived on Kauai.
  • The Moa-Nalo ( Thambetochen chauliodous Olson & Wetmore, 1976) lived on Molokai, Maui and Lanai.
  • The Oahu Moa Nalo ( Thambetochen xanion Olson & James, 1991) lived on Oʻahu.
  • The Maui Moa Nalo ( Ptaiochen pau ) lived on Maui.

Individual evidence

  1. ↑ a b c d Storrs L. Olson, Helen F. James: Descriptions of Thirty-Two New Species of Birds from the Hawaiian Islands: Part I. Non-Passeriformes. In: Ornithological Monographs. 1991, pp. 1-88, doi: 10.2307 / 40166794 .
  2. ↑ a b c Michael D. Sorenson, Alan Cooper, Ellen Paxinos, Thomas W. Quinn, Helen F. James, Storrs L. Olson, Robert C. Fleischer: Relationships of the extinct moa-nalos, flightless hawaiian waterfowl, based on ancient DNA. In: Proceedings B. The Royal Society Publishing, London 1999, pp. 2187-2193, doi: 10.1098 / rspb.1999.0907 , PMID 10649633 , PMC 1690346 (free full text).
  3. Jump up ↑ TJ Givinish, KJ Sytsma, JF Smith, WJ Hahn: Thorn-Like Prickles and heterophylly in Cyanea: Adaptions to extinct avian Browsers in Hawaii. In: PNAS . Volume 91, Washington, DC 1994, pp. 2810-2814.
  4. ^ Bradley C. Livezey, A Phylogenetic Analysis of Geese and Swans (Anseriformes: Anserinae), Including Selected Fossil Species. In: Systematic Biology. Volume 45, No. 4 (Dec., 1996), pp. 415-450, doi: 10.2307 / 2413524 .
  5. ↑ David A. Burney, Helen F. James, Lida Pigott Burney, Storrs L. Olson, William Kikuchi, Warren L. Wagner, Mara Burney, Deirdre McCloskey, Delores Kikuchi, Frederick V. Grady, Reginald Gage II and Robert Nishek: Fossil Evidence for a Diverse Biota from Kaua'i and Its Transformation since Human Arrival. In: Ecological Monographs. 71, 2001, p. 615, doi: 10.2307 / 3100038 .