Geology of the Provinces of Canterbury and Westland, New Zealand : a report comprising the results of official explorations
(B) The Dinornithidæ or Moa
(B) The Dinornithidæ or Moa.
This chapter would be incomplete were I not to offer a few observations on the Dinornithidœ, the great extinct wingless birds of New Zealand. It has been the good fortune of the Colony, that some, if not the very first Moa bones discovered in New Zealand, were handed over to Professor R. Owen, F.R.S., the illustrious pupil and successor of Cuvier, and from that date, November, 1839, or for nearly 40 years that great comparative anatomist has continued his work on our extinct Avifauna, on the ample material gradually furnished to him from the Colony. The first description was given in the "Proceedings of the Zoological Society of London," for November, 1839. For several years the material accumulated, so that Professor Owen in a paper communicated November 28, 1843, to the same Society could already describe six species, of which Dinornis giganteus was the largest, and Dinornis otidiformis the smallest, all from specimens collected in the Northern Island. In the course of the next 35 years, twenty more papers on the same subject were published by him in the same Transactions, now dealing however mostly with a number of species of the Dinornithidœ and a few other birds, belonging to some other orders, all laving been obtained in this (the South) Island.
Mention must here, however, be made of an important paper published in the "Annals and Magazine of Natural History" of August, 1844, written by the Rev. W. Colenso, F.L.S, who as far back as 1838, began to devote much attention to our extinct Avifauna. It bears the title, "An account of some enormous fossil bones of an unknown species of the class Aves, lately discovered in New Zealand." In this interesting paper the writer gives some valuable information and correctly places the fossil bones closely to Apteryx.page 432
The following species were described by Professor Owen, from this Island*:—
|Dinornis maximus||10 feet 6 inches.|
|Dinornis robustus||8 feet 6 inches.|
|Dinornis ingens (Palapteryx)||6 feet 0 inches.|
|Dinornis gracilis||5 feet 3 inches.|
|Dinornis struthioides||5 feet 6 inches.|
|Dinornis casuarinus||4 feet 10 inches.|
|Dinornis didiformis||4 feet 2 inches.|
|Dinornis elephantopus||5 feet 4 inches.|
|Dinornis crassus||4 feet 2 inches.|
|Dinornis gravis||4 feet 6 inches.|
|Dinornis rheides||4 feet 2 inches.|
Dinornis giganteus, dromioides, and curtus described from bones obtained in the Northern Island, have hitherto not been found in this Island, where they are doubtless represented by nearly allied species. There are still several species of the Dinornithidœ of both Islands, mostly of small size, still undescribed, of which, however, the Canterbury Museum possesses only single bones.
Besides these struthious birds, remains of some other remarkable birds contemporaneous to them and of considerable size, when the orders they belong to, are taken into account, have been discovered with them. The following were described by Professor Owen:— Rallidœ: Aptornis otidiformis, Aptornis defossor, Notornis Mantelli, the latter said to be still living in the south-west corner of this Island in mountainous regions, Anatidœ Cnemiornis calcitrans†
* The different sizes added, represent the mean height of a number of specimens of each species in the Canterbury Museum. All these species with the exception of geranoides have been found in this province.
† Dr. Hector, F.E.S., in Vol. VI., of the "Transactions of the New Zealand Institute" has given also a description of this species, at the same time pointing out ita anserine character.
There are still some naturalists who think that the division of the bones of our extinct Avifauna into so many species is a mistake, and that future researches will prove that what appeared to Professor Owen as several well-defined species, were after all, only various stages of age and growth of one and the same kind. However, in this respect, the collections of the Canterbury Museum bear a strong confirmation of the correctness of the great English anatomist's conclusions. We possess, not only young bones of each species, from the chick to the full grown bird, where—to take only one bone as guide—the tarsal epiphysis of the metatarsus is not yet quite anchylosed,* but we have of each species a series of specimens of generally two well distinct sizes, from which we may conclude that they represent the male and female bird of such species. In some instances, we possess four distinct sizes, which might represent the two sexes of two distinct but closely allied species.
Referring to the list of species, it will be seen that Professor Owen includes all the Dinornithidœ under one genus Dinornis, and abolishing even his former genus Palapteryx, thinking that the back toe (Hallux) was only a small functionless appendage to the foot. Although I was of opinion that the back toe might prove a good distinctive character for the grouping of the different genera, there seems, judging from the discovery during the last few years of several nearly complete skeletons in Otago and Canterbury, all probability that Professor Owen's views on that point are correct. However, I believe there exist many more distinctive features of great usefulness for the separation of the principal groups, and that my attempt in 1874 to make such divisions, is a step in the right direction. I then proposed the following sub-divisions:—A. family Dinornithidœ; a. genus Dinornis. 1. Dinornis maximus. 2. Dinornis robustus. 3. Dinornis ingens. 4. Dinornis [unclear: struthiodes]. 5. Dinornis gracilis; b. genus Meionornis. 1. Meionornis casuarinus; 2. Meionornis didiformis. B. family Palapterygidœ; a. genus Palapteryx. 1. Palapteryx elephantopus. 2. Palapteryx crassus; b. genus Euryapteryx. 1. Euryapterys gravis. 2. Earyapteryx rheides.
* We possess amongst others, the leg bones of a specimen of Dinornis maximus which is in size only second to the largest bones we have, but in which this immature character in the metatarsus is not yet quite effaced.
Anybody examining the skeletons of the different species ranged under the proposed genera, will at once admit that they have many natural and distinct characteristics in common, separating them at once from the other proposed genera. Professor Owen, in his last Memoir (XXI), has drawn attention to the generic sub-divisions of the Dinornithidæ as proposed by Reichenbach in an excellent work "Das natürliche System der Vögel" 4to, 1849 and 1850. I wish however, to point out, that when Reichenbach published his work, comparatively little was known of the osteology of the Dinornithidæ, the third memoir of Professor Owen having scarcely been printed. Consequently the eminent German ornithologist had not material enough upon which to place a sound basis for his proposed sub-divisions, and I am convinced that otherwise, they would have been somewhat different, and more in accordance with the genera into which the Dinornithidæ have naturally to be classed. Thus instead of separating D. giganteus, struthioides and ingens, into three genera, he would certainly have united them, they having all three some of the principal characters in common. The same can be said of D. didiformis and casuarinus. However, as more facts are gathered, more light will be thrown on this question, which after all is of minor importance, and only a matter of opinion till a still larger number of complete skeletons have been secured.
Professor Owen having described at some length in several of his memoirs on Dinornis, the affinity our struthious birds bear with those of other countries, and having pointed out at the same time, the peculiarities in which they vary from them, it would have been unnecessary for me to add anything to the subject, had not the attempt been lately made by Professor Alphonse Milne-Edwards, in Paris, to show from a comparison of the remains of the extinct ornithic fauna exhumed in Madagascar, Mauritius, and Rodriguez, that in some distant ages New Zealand formed portion of a large continent or of a group of more or less extensive islands in the Southern Hemisphere, which at one time were in some way connected with each other.
He thinks that additional confirmation can be obtained from the ascertained occurrence of different Ocydromidæ, such as the Aphanapteryx and the Miserythrus Leguati, which latter, he informs me (letter to me, dated Jardin des Plantes, Paris, Aug. 3, 1873), bears close resemblance to our common woodhen (Ocydromus Australis). However enticing the tracing of close affinities must be to the naturalist-philosopher, I believe, that it would be rather rash to conclude the connection of two such distant insular groups from a few forms of page 435birds only. Leaving the general question alone for the present, to which I shall return shortly, it is impossible for me to conceive that two countries, which in all other respects have such a dissimilar and distinctive flora and fauna could have been united in any way, without having left other living proofs of such connection in their present endemic organic life, not to speak of fossil remains. We know that Madagascar is a zoological sub-province of South Africa (Ethiopian region), but that it has a fauna so peculiar, that it must have, according to Sir Charles Lyell, been separated from Africa probably since the Upper Miocene era. New Zealand, on the other hand, although it may have been formerly of larger extent, has never been more than an oceanic continental island from a zoological point of view, a theory first propounded by Darwin and Wallace, and with which I fully agree. It would be a rather difficult task to prove upon such slender grounds as the presence of a few species of struthious and ralline birds may afford, that both countries might possibly have been connected. Moreover, the difference in the anatomical structure of the three Madagascar species of Aepyornis and of the New Zealand Dinornithidæ —using this latter term in a general sense—is so enormous that I fail to see how they possibly could prove that connection in anyway.
I cannot agree with Professor Alphonse Milne-Edwards, that the Aepyornis stands nearer to the Dinornis than to the Ostriches, Casuaries and Emus, except in so far that the fossil bones of Madagascar and New Zealand have a more pachydermal type, than the living species abovenamed. But I may point out, that the fossil Dromornis Australis of Australia shows similar characteristics, and I am sure if fossil remains of struthious birds in beds of post-pliocene age were discovered in Africa, America, and Asia that they would exhibit a similar pachydermal character. Judging from Professor Milne-Edwards' own excellent memoirs on the Aepyornis and the fine casts of the unique fossil bones in the Paris Museum, he was good enough to send to the Canterbury Museum I am unable to trace their relationship with our Dinornithidæ. It appears to me that the Madagascar species are separated from the former by many fundamental differences, such as (to point out only a few ) the pneumatic foramen in the femur and the straightness of the trochleæ of the metatarsus. And although I am convinced that the struthious character of Aepyornis has sufficiently been proved by the eminent Paris comparative anatomist, I can easily understand that there was at first some show of reason for placing it amongst the sarcoramphous vultures, as has been done by Professor Bianconi.page 436
However, speaking of the principle itself, I wish to point out, if we were to decide from a few isolated species in two distant countries which show some or even a close resemblance to each other, that these countries must have once been connected in some way, we should in many instances form erroneous conclusions, We might as well say that because there are struthious birds in Australia, the Malay Archipelago, Africa, America, and Asia, all these countries have been connected with New Zealand, or because marsupial remains have been found in secondary rocks in Europe and several species of opossums are living in America, these countries had also been united with Australia.
Speaking from a general point of view, I wish to add, that the attempts to trace the geographical relations of the fauna and flora of a country can easily be exaggerated, and thus a theory be ridden to death which otherwise would be very useful. Can the explanation of any specific resemblance in two distant countries not be found in many instances at least, in the adoption of more simple natural causes, such as the transport by icebergs, or on floating islands, by birds, etc., and of which Sir Chas. Lyell, in his great work, the "Principles of Greology," gives many striking instances? However, where the theory of land connection is not admissible, and where also others, which have hitherto been applied, fail, might we not assume that similar climatic and other physical conditions could produce similar specific characters under the great law of evolution? It is a most difficult problem to say what constitutes a species, and therefore might it not be safer to believe until the impossibility of such an hypothesis has been demonstrated satisfactorily, that there exists a similitude as well as an identity of species under certain given conditions. In one word, might we not throw out the conjecture that in two more or less distant countries which never were directly united, some forms of organic life can and do exist, which show what to us appears identical specific characters, because the cause or causes of their evolution were identical or nearly identical, and thus a considerable number of supposed changes in the level of many countries of which we do not find geological records, can be dispensed with. It is true, that instances to be explained by the migration or accident theories are of more frequent occurrence and more easily proved, but 1 think it would be just as interesting, where these cannot be admitted, to trace in all its bearings the similitude of species in distant countries. This view would, at least, open up a field of fresh research, and afford a new illustration and confirmation of the great theory of evolution.