Art. XXXVII.—Description of some Moa, Remains from the Knobby Ranges.
[Read before the Otago Institute, 13th July, 1874.]
The remarkable remains of the Moa which I have to describe were found by G. E. Allen, Esq., of Hawkdun Station, on the 4th of June last, on Messrs Campbell and Low's Galloway Station, Manuherikia district, in a crevice among mice-schist rocks, and were liberally presented by him to the Otago Museum.
Mr. Allen informs me that the crevice in question was two or three feet broad, five or six feet deep, and open at the top. The only covering the bones had was long rank grass growing up around them, and some of them were not covered at all.
The bones consist of a right metatarsus, with portions of the toes; a fragment of the left metatarsus; a right tibia; a left femur; and a fragment of a sternum. Judging by the measurements I believe them to belong to Dinornis ingens, Owen.
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In this unique specimen the whole of the skin and muscles of the posterior side are well preserved, while on nearly the whole of the anterior side they have gone. The bone thus exposed is bleached quite white, and the animal matter so much removed that the bone adheres to the tongue like ordinary Moa bones found on the surface, while the anterior surfaces of the trochleæ are considerably honeycombed and decayed. The hind-toe (hallux) is well preserved, being held in its position by the skin, but the horny claw covering the last joint has disappeared. Of the inner toe only the first joint remains, together with the flexor muscles. Of the middle toe the first two joints are left united with the skin of the sole of the foot, but in the second the bone is considerably decomposed. Of the outer toe all the joints are in their places, and the skin still covers the lower, outer, and part of the upper surfaces, but in this case also the horny claw is wanting, and the tip of the last joint (ungual phalanx) has decayed away.
The integument on the under surface of the toes is covered with small conical papillæ, about one-tenth of an inch in diameter at the base, which increase in size towards the sole of the foot. There is a marked protuberance under the first and second joints of the outer toe. The papillæ here are larger and closely packed together, while on the outside of the toe they are small and rounded. The surface of the integument on the upper side of the toe has been removed. On the back of the metatarsus the integument is covered by large irregular prominences nearly half an inch in diameter, divided by grooves from a tenth to a twentieth of an inch across, which are rough to the touch. These prominences are worn down quite flat, as proved by their striated surfaces, showing evidently that the Moa, like the emu, spent a considerable portion of its time with the lower surface of the metatarsus resting on the ground.
On the sides of the leg the prominences are flat, slightly lengthened longitudinally, and with a divided wart-like surface. They are about the same size as those on the lower surface, but are set closer together, and are arranged in irregular longitudinal rows. On the sides of the tibio-metatarsal articulation the prominences are smaller, more rounded, and higher. Judging from the fragment of integument left on the anterior side of the metatarsus, its surface appears to have been covered with flat, more or less rounded,
prominences in quincuncial arrangement, separated by flat smooth interspaces about a tenth of an inch wide. There is no appearance of its having been covered with horny scales as in Apteryx. In colour the integument is yellowish brown, getting paler on the posterior surface; while the bones, including the last (ungual) joint of the hind toe (pl. XIX., e), are bleached quite white.
Of this bone only a portion of the posterior half of the distal end remains, the rest having entirely decayed away.
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|Fibular ridge extends down||11||5|
The cartilage still extends over the lower epiphysis; but the upper articular end is quite decayed and rotten. Small lichens and Metzgeria furcata grow on the anterior surface close up to the cartilage.
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This bone is much decayed, and covered on its anterior side with small lichens.
A fragment of the right upper corner remains, showing an apparently small costal process, a rather shallow coracoid groove, and with the lateral process but slightly diverging. The whole bone seems to have been very small for so large a bird, as it by no means equals that of Dinornis elephantopus.
In conclusion I would remark that the extraordinary juxtaposition of decayed and lichen-covered bone with well-preserved skin and flesh seems to me to point to some peculiarity in the atmosphere which enables flesh to resist decay when shaded from the rays of the sun, and by no means to prove that the bird to which this skin and flesh belonged lived at a later date than those whose bones we now find buried under the soil.
For the following valuable notes I am indebted to my friend Dr. Millen Coughtrey.
Anatomical Notes on the Moa's Leg found at Knobby Ranges in the Province of Otago. By Millen Coughtrey.
It is the right leg, and is composed of the following bones held together by muscles and ligaments:—R. tarso-metatarsus, and bones of 1st, 2nd, 3rd, and 4th toes; in addition a calcaneo-sesamoid bone at the tibio-tarsal joint, and a sesamoid cartilage at the metatarso-phalangeal joint.
The joints, sesamoids and muscles, even though fragmentary, in an extinct bird must be of interest, and I will therefore describe them with care.
Tibio-tarsal joint, i.e., the joint between distal end of tibio-tarsus and proximal end of tarso-metatarsus.
The ecto- and endo-condylar fossæ and the intercondylar ridge of the R. tarso-metatarsus are still covered by articular cartilage, which, though brown and dry with age, still presents distinctive characters.
The ecto-condylar fossa is as broad as long, and is shallow; the endocondylar fossa is longer than broad and is deep.
The margins of these fossæ are sharply defined and prominent with the exception of the posterior border of the ecto-condylar fossa, which is rounded from before backwards so as to adapt it for the shape, and to facilitate the movements on it of a sesamoid bone. * (Pl. XIX., fig. 1, a.)
The marginal prominence, and consequently the increased depth of the fossæ, is caused by a rim of fibro-cartilage (fig. 1, b) which is fused into the margin of the true articular cartilage in all parts except one, viz., the outer and posterior margin of the ecto-condylar fossa.
This separation is natural, and the free part is semilunar in form (fig. 1, c), bevelled from without inwards, and so contributing materially to increase the depth of the fossa at the sides in a somewhat similar way to what the semi-lunar cartilages act in the knee-joint of man.
This free semilunar cartilage is continuous with the sharp cartilage skirting the antero-inferior border of a sesamoid bone to be afterwards described.
Calcaneo-sesamoid bone, fig. 1, a:—
Its position has been before mentioned. Its general form is pyramidal, having two ends, three surfaces, and three borders.
[Footnote] * The difference between the two fossæ at their posterior margin may be well seen in a bone denuded of cartilage. The calcaneo-sesamoid bone is only connected with the ecto-condylar fossa. Yet it is right I should mention a curious fact observed by Captain Hutton when superintending the excavation of the Moa remains at Hamilton Swamp. He observed a leg of the Moa (probably D. elephantopus?) or D. crassus?) with all the bones loose but in sitù, and he especially noticed in this case two sesamoid bones at the tibio-tarsal joint. Bearing in mind the general positions and functions of sesamoid bones, the morphology of the tibio-tarsal joint in other birds, also the marked inarticular character of the posterior margin of the endo-condylar fossa in Dinornis, together with the degree of prominence and strength of the endo-calcaneal process, I should think it quite possible that the second sesamoid bone Captain Hutton saw in the Hamilton Swamp specimen was from the opposite limb, and had fallen accidentally into apposition with the other one.
The outer end is blunt and equals the base of pyramid, the inner end is acute and curved.
The inferior surface is situated between the antero-inferior and the postero-inferior borders; it is concave, and adapted for playing on the convexity of the posterior border of ecto-condylar fossa.
The anterior surface lies between the superior and the antero-inferior borders; outwardly it presents a shallow concavity, which plays on the outer half of posterior and inferior surface of the tibial trochlea, whilst its inner moiety presents a convexity which acts the part of a movable intercondylar ridge to the back part of the tibial intercondylar groove.
The posterior surface is between the postero-inferior and the superior borders, and is convex in contour. It is bare and denuded of cartilage, but presented the appearance of having at one time had a thin layer, and I should fancy from the position of the tendons to it, much bursal tissue formerly existed between it and them.
A band of dried ligament connected the posterior margin of the sesamoid bone with a depression at the back part of the intercondylar ridge of the tarso-metatarsus.
There are a few ligamentous remains attached to the apex of the calcaneo-sesamoid, but their other attachments are broken.
The tibio-tarsal bone of same side and same creature was found with the above. Its distal extremity has a thin layer of articular cartilage spread over its articular portion in a much more weathered state than that found on opposing articular surface of this joint; remains of ligaments are left in the pits on the lateral faces of the condyles, and from the more prominent tuberosity of the outer condyle a marked tuft of ligament proceeds.
These are the remains of the outer and inner lateral ligaments of the joint.
The outer toe is complete, the middle toe has its two proximal bones, and the inner or second toe has only its proximal segment. The hallux is entire but displaced from its normal position.
The posterior and inferior faces of the trochleæ of matatarsal bone are covered with articular cartilage, but the anterior faces of these trochleæ were bare, and the bone much worn and weathered (fig. 1, d.)
The opposing articular surfaces of the proximal phalangeal bones are covered with articular cartilage.
Strong bands of ligament (the lateral portions of the capsular ligaments) are present in the outer and middle toes on both sides, and on the outer side of the inner toe, the proximal attachments of these ligaments are to the lateral faces of the trochleæ.
The phalangeal joints were nearly complete, those of the fourth toe quite entire; the under portions of the capsular ligaments are grooved for tendons and specially thickened.
The conjoined tendon of G. internus and G. externus is well seen, and its respective connections to the ento- and ecto-gastrocnemial surfaces still remain. The inner insertion is neither so strong nor so extensive as the outer one.
The ento-gastrocnemial insertion begins behind and below the endo-metatarsal tuberosity by a rough patch which runs into a strong ridge that ends on the posterior aspect of the inner margin of tarso-metatarsus at a point about two inches above the inner trochlea (fig. 2, f.)
The ecto-gastrocnemial insertion is in its upper part with greater difficulty made out, owing to its being partly covered by the hardened inflexible skin, which it was not thought advisable to disturb. It is attached to the outer border of tarso-metatarsus, and terminates in a distinct impression about three-quarters of an inch from the outer trochlea, from which it is separated by a deep but smooth groove. (This groove presents all the appearances of a vascular groove, in which an artery and a vein have formerly lain.)
The outer insertion is separated from the bone at one point to allow a tendon * to pass from the front of leg to the back; this point is at the junction of the upper third with the lower two-thirds of bone; but above and below this point the outer insertion is very firm and strong.
Between the two gastrocnemial surfaces a portion of the periosteum of bone is left, and the periosteum receives many fibres from the gastrocnemius at these surfaces.
There was no connection between this muscle and the sesamoid cartilage at the tarso-phalangeal joint, nor did any slip pass from the gastrocnemius to the flexor perforatus, thus differing from what has been observed in the ostrich. †
The flexor tendons ran beneath the arch formed by the conjoined tendon.
Although there is a distinct hallux (fig. 2, a) present, there are no appearances by which it could possibly be asserted that it had been in this case attached to the lower end of the ento-gastrocnemial ridge.
b.—Flexor Tendons of the Toes:—
These are in a very fragmentary condition.
There are distinctly four flexor tendons on the back of the tarso-metatarsal
[Footnote] * Can this tendon be that peculiar tendon of the Pectineus, Owen; (or Rectus anticus femoris of Cuvier), fig. 1, x.
[Footnote] † Dissection of an Ostrich. A. H. Garrod, B.A., and Frank Darwin, B.A. Proc. Zool. Soc. 1872, pl. I., p. 361.
bone; of these four tendons one is a broken portion (fig. 2, g), a second is twisted much out of position, and its fibres unravelled (fig. 2, h), the other two are quite entïre (fig. 2, i).
They can easily be divided into two sets—a posterior or superficial pair, and an anterior or deep pair.
And this is best seen where they are enclosed in an aponeurotic sheath just above and behind the tarso-phalangeal joint.
The above aponeurotic sheath being divided into two main canals, one anterior to the other, each containing two tendons, those lying in the posterior canal are the tendons of the flexor perforatus digitorum (fig. 2, g, h), those in anterior canal being the deep flexor tendons (i) (flexor perforans digitorum pedis), but in both cases only to the third and fourth toes.
The superficial and deep flexors to second toe will be separately described.
Between the deep flexors and the posterior surface of middle trochlea a sesamoid cartilage * is interposed; from the sides of this cartilage springs the aponeurotic archway, which has been before mentioned; the septum between the two divisions of this archway is thick and semi-cartilaginous.
The flexor tendons after being conducted by this aponeurotic sheath beyond the tarso-phalangeal joints, break up and run to their respective attachments.
The greater part of tendons of flexor perforatus end in lateral slips to the bases of proximal segments of third and fourth toes; there are second perforated tendons to the outer and third toe, those to latter toe being broken across.
The two tendons of flexor perforans respectively to the third and fourth toes each subdivides into four slender slips, which have that flattened character and imbricate relations to one another peculiar to digital tendons; the termination of those to outer toe is indistinct, except that the two deepest seem to unite and become attached to base of ungual segment, while the two superficial ones go to base of third segment of outer toe. The deep flexors of third toe are broken across opposite second phalangeal joint.
The inferior portions of the capsular ligaments of the phalangeal joints are strengthened and grooved for the passage of these tendons.
Inner or Second Toe:—
The proximal phalanx of this toe was the only part left, it was quite loose and it has to be retained in situ by artificial means; its external lateral ligament, however, is present.
To its base there still remain attached several tendons, and a portion of the annular ligament retains others.
It is quite clear that the superficial and deep flexors to this toe did pass through a separate and distinct aponeurotic sheath to that of the third and
[Footnote] * Same has been seen in ostrich. Loc. cit., p. 361.
fourth toes. They also possessed a separate semi-sesamoid, there being a fibiocartilaginous plate of about a quarter inch in thickness interposed between them, and the back of inner trochlea and its tarso-phalangeal joint. (Fig. 1, e).
From the margins of this fibro-cartilage arises the annular sheath of this digit, and this is partially divided by septæ for the tendons.
The tendons left are:—
About 4 inches of outer slip of flexor perforatus (fig. 1, f) to base of proximal bone of this toe, the stump of inner slip.
A small tendon enclosed in a separate sheath outside the annular ligament, and ending in the outer side of the base of this bone. It lies at the outer margin of the ligamentous substance. What it is I am unable to say-Fig. 1, g indicates its position.
Lying within the annular sheath tendons, that present two strong bundles proximally (fig. 1, h), but are so dishevelled and unravelled distally (fig. 2, h) that it is impossible to differentiate them into separate tendons possibly deep flexors, for they are evidently the remains of tendons passing to the distal segments of this toe.
c.—Tibialis anticus (fig. 2, i):—
A mere tuft of the insertion of this tendon is left, but it is clearly defined slightly below and to the side of the anti-interosseal canal, from which it is separated by a bridge of bone.
The anti-interosseal canal is large, and its bifurcation is deeply situated. fig. 1, k
d—Extensor longus digitorum, pedis, (fig. 1, l):—
A portion of the tendon of this muscle is left, (fig. 1, b), the rest of extensor group of tendons are destroyed.
Inserted into a depression beneath and in front of ecto-metatarsal tuberosity is a tendon, what it is (?) I do not know (fig. 1, m).
The scraps marked n in fig. 1 and l in fig. 2 indicate displaced portions of the gastrocnemii.
For a detailed account of skin and degree of decay see Captain Hutton's part of this paper.
Had the peculiar distinctness and separation of the tendons going to the second toe anything to do with peculiar motion of this digit in the Moa?
References to Plate XIX.
Fig. 1 indicates anterior aspect of specimen.
d., anterior faces of trochleæ. 1′, inner; 2′, middle; 3′, outer trochlea.
Fig. 2 indicates posterior and inner aspect of specimen.
a. hallux; b., ungual segment of fourth toe; c., second segment of third toe; d., proximal segment of second toe; e′., refers to the decayed left tarsometatarsus.
The remaining references are distributed throughout the description.