MOA, apparently the Maori name of the extinct Ratite birds in New Zealand, comprising the group Dinornithes (cf. BIRD: Classification; and RATITAE). The earliest account of these birds is that of Polack (New Zealand, London, 1838), who speaks of the former existence of some struthious birds in the north island as proved by fossil bones which were shown to him. " The natives added that, in times long past, they received the tradition that very large birds had existed, but the scarcity of food, as well as the easy method of entrapping them, had caused their extermination." In the North Island the moas seem to have died out soon after the arrival of the Maoris, according to F. W. Hutton, some 700-500 years ago. In the South Island they seem to have lingered much longer, possibly, according to H. O. Forbes (Nat Set. II. 1893, pp. 374-380), " down even to the time that Captain Cook visited New Zealand." But these are only surmises, based upon the fact that in various dry caves limbs still surrounded by the mummified flesh and skin, feathers, and even eggs with the inner membrane, have been found. Great quantities of bones have been found in caves and in swamps, so that now nearly every part of the skeleton, of some kind or other, is known.
The most striking feature of the moas, besides the truly gigantic size of some species, is the almost complete absence of the wings. In fact, the whole skeletons of the wings and of the shoulder girdle seem to have been lost, excepting Anomalopteryx dromaeoides, which, according to Hutton, 1 had still some vestiges. Such a complete reduction of the whole anterior limb and girdle is unique among birds, but the cassowaries indicate the process. In conformity with these reductions the breastbone of the moas is devoid of any coracoidal facets; there is no trace of a keel, and the number of sternal ribs is reduced to three or even two pairs. The hind limbs are very strong; the massive femur has a large pneumatic foramen; the tibia has a bony bridge on the anterior surface of the lower portion, a character in which the moas agree only with Apteryx amongst the other Ratitae. The number of toes is four, unless the hallux is more or less reduced. The pelvis much resembles that of the kiwis.
The skull has been monographed by T. J. Parker (" On the Cranial Osteology, Classification and Phylogeny of the Dinornithidae," Tr. Z. Soc. (1893), xiii. 373-431, pis. 56-62); it resembles in its general configuration that of the emeus ana cassowaries, while it differs from that of Apteryx most obviously by the short and stout bill.
The feathers have a large after-shaft which is of the size of the other half, likewise in agreement with the Australian Ratitae, while in the others, including the kiwis, the after-shaft is absent. Another important point, in which the moas agree with the other Ratitae and differ from the kiwis, are the branched, instead of simple, porous canals in the eggshell.
1 " The Moas of New Zealand," Tr. N. Zea. Inst. (1892), xxiv. 93-172, pis. xv.-xvii.
The affinities of the moas are undoubtedly with the Australian Ratitae, and, in spite of the differences mentioned above, with the kiwis. In this respect Max Fiirbringer and T. J. Parker are in perfect agreement. The relationship with Aepyornis of Madagascar is still problematic. Whilst the moas seem to have been entirely herbivorous, feeding not unlikely upon the shoots of ferns, the kiwis have become highly specialized wormeaters. In this respect cassowaries and emeus hold an intermediate position, their occasional zoophagous (especially piscivorous) inclination being well known. Unmolested by enemies (Harpagornis, a tremendous bird of prey, died out with the Pleistocene), living in an equable insular climate, with abundant vegetation, the moas flourished and seem to have reached their greatest development in specialization, numbers, and a bewildering variety of large and small kinds, within quite recent times. Unfortunately no fossil moas, older than the Pleiocene, are known. Parker recognizes five genera, with about twenty species, which he combines into three sub-families: Dinornithinae with Dinornis, Anomalopteryginae with Pachyornis, Mesopteryx and Anomalopteryx, comprising the comparatively least specialized forms; and Emeinae with the genus Emeus, not to be confounded with the vernacular emeu. The moas ranged in size from that of a turkey to truly colossal dimensions, the giant being Dinornis maximus, which, with a tibial length of 39 in., stood with its small head about 12 ft. above the ground.
(H. F. G.)
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)