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Volume 25, 1892
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Art. IV.—On Anomalopteryx antiqua.

By Captain F. W. Hutton, F.R.S.

[Read before tke Philosophical Institute of Canterbury, 7th September, 1892.]

Plate IV.

In my paper on the moas read to this society last year I mentioned some moa-bones which had been found under a lavastream near Timaru, and named them Anomalopteryx antiqua. The description was very imperfect, as I had only seen two fragmentary tibiæ, both of which were much hidden by the matrix in which they were imbedded. I also mentioned that two fragments of a metatarsus, free from matrix, had been found, but that I had not been able to see them. These fragments are shown in the plate accompanying my paper (Pl. IV.), which is taken from a photograph given me by Mr. G. Hogben. They are still missing, but while they were in Mr. Forbes's possession he had moulds made in the museum, and from these I have obtained casts which enable me to add considerably to my former description of this interesting bird. These casts consist of two fragments of a right metatarsus and a small portion of what may be the shaft of a femur.

Proximal Portion of the Metatarsus. Plate IV., figs. 1, 2.

The width is 51mm. (2in.), and the depth, from the bottom of the hypotarsal groove, is 34mm. (1.33in.). The intercondylar ridge is high, projecting in front and rising considerably above the hypotarsal groove: the outer condylar depression is considerably broader and shallower than the inner. The ectocondylar ridge is also high. The inner margin is simply rounded without any longitudinal ridge on the tarsal portion of the bone: the anterior margin is rather strongly sinuated, showing two concavities, one on each side of the intercondylar ridge. The hypotarsal groove is shallow, owing to the slight development of the inner ridge; but the outer ridge is well developed and much broader than the inner one. The interosseous canals, between the metatarsals, open anteriorly together in a deep but small pit, as is usually the case in the Dinornithidœ, and the rough surface for the insertion of the tendon of the tibialis anticus is small.

Distal Portion of the Metatarsus. Plate IV., figs. 3–5.

In this fragment the outer trochlea and the outer portion of the middle trochlea are missing. The inner trochlea has a width of 18mm. on its anterior surface, and

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a depth of 23mm.; so that the anterior width is less than the depth. The anterior surface is not so oblique as is usual in the other small species of moa, but makes almost a rightangle with the outer surface. It is also directed inwards well within the inner edge of the middle trochlea (fig. 4). The most remarkable character, however, is its flatness behind (fig. 5), the posterior process, which is so large in all other moas except Palapteryx dromioides, being here quite small. The trochlear groove is slight.

The middle trochlea is considerably broader than the inner one, its width being probably about 28mm., but it tapers off rapidly so that its distal width is only about 19mm. Its depth is 26mm. It does not project so far forwards as in most other moas.

The intertrochlear gorge is broad and does not narrow so much at its entrance (figs. 3–4) as in all other moas except Cela curta. Its width at the entrance is nearly half that of the inner trochlea.

Supposed Femur. Plate IV., fig. 6.

This is nearly cylindrical, the greatest and least diameters being 28mm. and 26mm. It is remarkable for the thickness of the bony wall, the diameter of the medullary cavity being only about 8mm. or 9mm. This great thickness of the bony wall makes it doubtful if the bone belongs to a bird at all. The only bones of the moa which have so relatively small a central cavity are the toe-bones, and these are always flat on the undersurface. It is also too large for a toe-bone of A. antiqua, while its diameter is about what we should expect in the femur of that species. As the bone has disappeared it is impossible now to make a microscopical investigation to test its avian or reptilian character.

Affinities of the Species.

In the high intercondylar ridge our species resembles Anomalopteryx didiformis, Mesopteryx didina, and Pachyornis (?) geranoides, and differs from Cela curta. In the sinuated anterior margin of the proximal articular surface it most resembles A. didiformis and P. geranoides, but in these species there is usually only a single concavity on the inner side of the intercondylar ridge. In the absence of a longitudinal ridge on the inner margin it resembles P. geranoides but this ridge is often absent in A. didiformis and C. curta. In the high ectocondylar margin it most resembles M. didina and P. geranoides. In the small inner hypotarsal ridge it approaches Emeus crassus, but A. didiformis sometimes has the inner ridge less than the outer.

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The middle trochlea does not project forwards so much as in C. curta or P. geranoides, and in this point again our species resembles A. didiformis. The inner trochlea is not produced so much as in M. didina or P. geranoides, but resembles that of C. curta and A. didiformis; it is, however, narrower in proportion to its depth than in either of those species. It agrees with A. didiformis in the more transverse direction of its anterior face, which in C. curta and in P. geranoides is directed almost to the inner edge of the middle trochlea.

The intertrochlear gorge is broader than in C. curta, but does not narrow so much at the entrance as in A. didiformis and all the other moas.

It thus appears that, while it has distinctive characters of its own, the affinities of A. antiqua are more closely with A. didiformis than with any other species. It differs, however, from A. didiformis in the narrowness and in the shape of the lower surface of the inner trochlea; in the shape of the intertrochlear gorge; in the more rapid tapering of the middle trochlea; in the double sinuation of the anterior margin of the proximal articular surface; and in the small inner hypotarsal ridge. The length of the metatarsus is not known, but the tibia is considerably shorter than that of A. didiformis.

It will thus be seen that my inference that the moa bones from Timaru belonged probably to the genus Anomalopteryx was a correct one.

Description of Plate IV.

Anomalopteryx antiqua.

Fig. 1. Proximal end of metatarsus, front view.

Fig. 2. " " proximal view.

Fig. 3. Distal end of metatarsus, front view.

Fig. 4. " " distal view.

Fig. 5. " " interior view.

Fig. 6. Section of supposed shaft of femur.

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Anomalopteryx antiqua nat size

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