1902 Encyclopedia > Kangaroo


KANGAROO. When Captain Cook, during his first memorable voyage of discovery, was detained, for the purpose of refitting his ship at Endeavor river, on the north-east coast of Australia, a strange-looking animal, entirely unknown to them, was frequently seen by the ship’s company; and it is recorded in the annals of the voyage that, on the 14th of July 1770, "Mr Gore, who went out this day with his gun, had the good fortune to kill one of the animals which had been so much the subject of our speculations,…. And which is called by the natives kanguroo," a name which, though it does not appear to be now known to any of the aboriginal tribes of the country, has been adopted for this animal in all European languages, with only slight modifications of spelling. With the exception of a passing glimpse in the beginning of the same century by the Dutch traveler Bruyn of some living examples of an allied species, to be referred to presently, this was the first introduction to the civilized world of any member of a group of animals now so familiar. The affinities of the species, skins of which were brought home by Captain Cook and subsequent voyages, were recognized by Schreber as nearer to the American opossums (then the only known marsupials) than to any other mammals with which zoologists were acquainted, and consequently it was placed by him, in his great work on the Mammalia, then in the course of publication, in the genus Didelphis, with gigantean for a specific designation, - the latter having been bestowed upon it by Zimmerman under the impression that it was a huge species of jerboa. Soon afterwards (1791) Dr Shaw very properly formed a new genus for its reception, which he named Macropus, in allusion to the peculiar length of its hind foot. By the name thus formed, macropus giganteus, this kind of kangaroo has ever since been known in zoological literature.

Kangaroo (Macropus giganteus) image

Fig. 1 -- Kangaroo (Macropus giganteus)

Futher explorations in Australia and the neighboring islands have led to the discovery of a very considerable number of species, which are now included in the family Macropodidae, one of the subdivisions of the order Marsupialia, for the characters of which see MAMMALIA.

The Macropodidae, or kangaroos, taken as a whole, form a very well marked family, easily distinguished from the remaining members of the order by their general conformation, and by peculiarities in the structure of their limbs, teeth, and other organs. They vary in size from that of a sheep down to a small rabbit. The head, especially in the larger species, is small, compared with the rest of the body, and tapers forward to the muzzle. The shoulders and fore limbs are feebly developed, and the hind limbs of disproportionate strength and magnitude, which gives them a peculiarly awkward appearance when moving about on all fours, as they occasionally do when feeding. Rapid progression is, however, performed only by the powerful hind limbs, the animal covering the ground by a series of immense bounds, during which the fore part of the body is inclined forwards, and balanced by the long, strong, and tapering tail, which is carried horizontally backwards. When not moving they often assume a perfectly upright position, the tail aiding the tow high legs to form a sort of supporting tripod, and the front limbs dangling by the side of the chest. This positions gives full scope for the senses of sight, hearing, and smell to warn of the approach of enemies, from which they save themselves by their bounding flight. The fore paws have five distinct digits, each armed with a strong, curved claw. The foot of the hind limb is quite different, and very peculiar in construction, being extremely long and narrow, and (with only one, lately discovered, exception) without any hallux or great tow. It consists mainly of one very large and strong toe, corresponding to the fourth of the human or other typically developed foot, ending in a strong curved and pointed claw. Close to the outer side of this lies a smaller fifth digit, and to the inner side tow excessively slender toes (the second and third), bound together almost to the extremity in a common integument. The two little claws of these toes, projecting together from the skin, may be of use in scratching and cleaning the fur of the animal, but the toes must have quite lost all connection with the functions of support or progressive.

The dental formula, when completely developed is incisors 3/1, canines 1/0, premolars 2/2, molars 4/4 on each side, giving a total of thirty-four teeth. the three incisors of the upper jaw are arranged in a continuous arched series, and have crowns with board cutting edges; the first or middle incisor is often larger than the others. Corresponding to these in the lower jaw is but one tooth on each side, but it is of great size, procumbent or directed horizontally forwards, narrow, lanceolate, pointed, and with sharp edges. Owing to the laxity of the union of the two rami of the lower jaw at the symphysis, in manyh species the two lower incisors can be made to work together like the blades of a pair of scissors, a very remarkable arrangement not known to occur in other mammals. The canines are absent or rudimentary, always so in the lower jaw, and often deciduous at an early age in the upper jaw. The premolars are compressed, with cutting longitudinal edges, the anterior one is always deciduous, being lost about the time the second one replaces the milk molar, so that both premolars are never found in place and use in the same individual. The true molars have quadrate crowns, provided with two strong transverse ridges, or with four obtuse cusps. In Macropus giganteus and its immediate allies, both premolars and one or two of the anterior true molars are shed during the lifetime of the animal so that in old examples only the two posterior molars and the incisors are found in place. The milk dentition, as in other marsupials, is confined into a single molar tooth on each side of each jaw, the other molars and incisors being never changed. The dentition of the kangaroos, functionally considered, thus consist of sharp-edged incisors, most fully developed near the median line of the month, for the purpose of cropping the various kinds of herbage on which they feed, and ridge and tuberculated molars for crushing it, there being no canines for offensive or defensive purposes.

Skeleton of hind foot of kangaroo image

Fig. 2 -- Skeleton of hind foot of kangaroo

The number of vertebrae is---in the cervical region 7, dorsal 13, lumbar 6, sacral 2, caudal varying according to the length of the tail , but generally from 21 to 25. In the fore limb the clavicle and the radius and ulna are well developed, allowing of considerable freedom of motion of the hand. The pelvis has large epipubic or ‘marsupial: bones. The femur is short, and the tibia and fibula of great length, as is the foot, the whole of which is applied to the ground when the animal is at rest in the upright position.

The stomach is of large size, and very complex, its walls being puckered up by longitudinal muscular bands into a great number of sacculi, like those of the human colon. The alimentary canal is long, and the caecum well developed. All the species have a marsupium or pouch formed by a fold of the skin of the abdomen, covering the mammary glands with their four nipples. In this pouch the young (which, as in other marsupials, leave the uterus in an extremely small and imperfect condition) are placed as soon as they are born; there their growth and development proceeds; and to it they resort temporarily for the purpose of shelter, concealment, or transport, for some time after they are able to run and jump about the ground and feed upon the same herbage which forms the nourishment of the parent. During the early period of their sojourn in the pouch, the blind, naked, helpless young creatures (which in the great kangaroo scarcely exceed an inch in length) are attached by their mouths to the nipple f the mother, and are fed by milk injected into their stomach by the contraction of the muscle covering the mammary gland. In this stage of their existence the respiratory organs are modified much as they are permanently in the Cetacea, the elongated upper part of the larynx projecting into the posterior nares, and so maintaining a free communication between the lungs and the external surface, independently of the mouth and gullet, thus averting all danger of suffocation while the milk is passing down the latter passage.

Skull and teeth of Bennett's kangaroo (image)

Fig. 3 -- Skull and teeth of Bennett's kangaroo (Macropus bennettii). i1, i2, i3 first,second and third upper incisors; pm, second or posterior premolar (the first having been already shed; m1, m2, m3, m4, the four true molars. The last, not fully developed, is nearly concealed by the ascending ramus of the jaw.

The kangaroos are all vegetable feeders, browsing on grass and various kinds of herbage, the smaller species also eating roots. They are naturally timid, inoffensive creatures, but the larger ones when hard pressed will turn and defend themselves, sometimes killing a dog by grasping it in their fore paws, and inflicting terrible wounds with the sharp claws of their powerful hind legs, sustaining themselves meanwhile upon the tail. The great majority are inhabitants of Australia and Tasmania, forming one of the most prominent and characteristic features of the fauna of these lands, and in the scenery of the country, as well as the economy of nature, performing the part of the deer and antelopes of other parts of the world, which are entirely wanting in Australia. They were very important sources of food supply to the natives, and are hunted by the colonists, both for sport and with a view to their destruction, on account of the damage they naturally do in consuming the grass, now required for feeding cattle and sheep. Notwithstanding this, they have in some districts increased in numbers, owing to the suppression of their former enemies, the aborigines and the dingo or native dog. A few species are found in New Guinea and the adjacent islands, which belong, in the zoological sense, to the Australian province, beyond the bounds of which none have been found either existing or in a fossil state.

The Macropodicae are divided into two well-marked sections – (1) the true kangaroos (macropodinae), and (2) a group consisting of smaller animals, commonly called rat-kangaroos, or (improperly) "kangaroo-rats," or sometimes potoroos.

I.In the macropodinae (see fig. 3) the cutting edges of the upper incisors are nearly level, or the first pair but slightly longer than the others. The canines are rudimentary and often wanting. The premolars are usually not longer (from before backwards) than the true molars, and less compressed than in the next section. The crowns of the molars have always two prominent transverse ridges. The forelimbs are small with subequal toes, armed with strong, moderately long, curved claws. Hind limbs very long and strongly made. Head small, with more or less elongated muzzle. Ears generally rather long and ovate.

Upward of thirty species of this group have been described, and many attempts have been made to subdivide it into smaller groups or genera for the convenience of arrangement and description, but these have generally been based upon such trivial characters that it is preferable to speak of most of them as sections of the genus Macropus, reserving generic rank only to two forms somewhat aberrant both in structure and geographical distribution. According to this arrangement the genera will be as follows:-

1. Macropus, Shaw, divided into the following sections or subgenera. A. Macropus proper, of which the type is M. giganteus spoken of at the beginning of this article as having been discovered in 1770 by the first English explorers of Australia. It is the common great kangaroo, called "boomer," "forrester," or "old man" mby the colonists, and frequents the open grassy plains of the greater part of eastern Australia and Tasmania. Some closely allied species or perhaps local varieties, M. ocydromus, M. fuliginosus, and M. melanops, are found in southern and western Australia. B. Osphranter, Gould, distinguished from the above by the naked muffle, includes some very large and handsome species, which principally dwell in rocky mountain ranges, as the great red kangaroo, M. rufus, M. antilopinus, and m. robustus. C. Halmaturys, F. Cuv. The kangaroos of this section have also the muffle naked, but they are rather smaller species, frequenters of forests and dense impenetrable brushes and scrubs, and hence often called brush kangaroos, though a native name "wallaby" is now generally applied to them. there are many species, of which M. bennettii, M. ruficollis, M. ualabatus, M. dorsalis, M. agilis, M. derbainus, M. thetidis, M. billardieri are the best known. M. brachyurus is remarkable for its comparatively short and slender tail and small ears. The earliest known species of kangaroo, referred to before, M. brunii (Schreber), may perhaps belong to this section. Several examples were seen by Bruyn in 1711 living in captivity in the garden of the Dutch governor of Batavia, and described and figured in the account of his travels (Reizen overMoskovie, &c) under the name of "Filander." It wasquite lost sight of an its name even transferred by S. Muller to another species (now known as Dorcopsis mulleri, Schlegel) until rediscovered in 1865 by Rosenberg, who sent a series of specimen to the Leyden Museum from the islands of Aru and Greak Key, thusdetermining its true habitat. Quite recently three other species of true kangaroo have been discovered out of Australia: - M. papuanus, Peters, from the eastern extremity of New Guinea, near Yule Island; M. crassipes, Pierson-Ramsay, from near Port Presby; and M. browni, Pierson-Ramsay, from New Ireland. D. Onychoyalea, Gould, with a hairy muffle and long and slender tail, furnished with a horny nail-like organ at the apex. M. unguifer, M. fraenatus, and M. lunatus. E. Lagorchestes, Gould, hare-kangaroos, a group of small hare-like animals, great leapers and swift runners, which mostly affect the open grassy ridges, particularly those of a stony character, sleeping in forms or seats like the common hare. Their limbs are comparatively small, their claws sharp and slender, and their muffle clothed with velvet-like hairs . M. fasciatus, M. leporoides, M. hirsitus, M. conspicillatus, &c.F. Petrogale, Gray. These differ from all the others in having the tail cylindrical and bushy towards the apex instead of tapering . the muffle is naked, the hind foot comparatively short and stout, and densely clothed with coarse hairs, the nails short. These are the "rock kangaroos," making their retreats in caverns and crevices, leaping with surprising agility from one narrow ledge to another, and browsing upon the scanty herbage that the neighborhood of such situations affords. M. xanthopus, M. penicillatus, M. lateralis, M. concinnus, M. brachyotus, M. inornatus, &c.

2. Dendrolagus, Sal. Muller. – A genus formed for the reception of two species, D ursinus and D. inustus, commonly known as "tree kangaroos," both inhabitants of New Guinea, and which differ greatly from all the foregoing in being chiefly arboreal in their habits, climbing with facility among the branches of large trees, and feeding on the bark, leaves, and fruit. In accordance with this habit their hinder limbs are comparatively shorter than in the true kangaroos, and their fore limbs are longer and more robust, and have very strong curved and pointed claws. These differ from all the preceding, and agree with the next genus, in some details of the structure of the molar teeth, and in the circumstance that the fur of the back of the neck is directed forwards or in a reverse position to that of the remainder of the coat.

3. Dorcopsis, S. Muller. – Of this genus two species are at present known, both from New Guinea, D. mulleri, and another lately discovered by D’Albertis, d. luctuosa. In some respects they resemble the last, but they differ from them and all the other Macropodinae, and agree with the next section, in the great size and joeculiar form of the premola teeth.

Skull and teeth of Gray's Rat Kangaroo (image)

Fig. 4 -- Skull and teeth of Gray's Rat Kangaroo (Bettongia grayii). c, upper canine teeth. The other letters as in Fig. 3.

II.The second section or sub-family, the Hypsiprymninae (see fig. 4), have the first upper incisor narrow, curved, and much exceeding the others in length. Upper canines always persistent flattened, blunt, and slightly curved. Premolars of both jaws always with large, simple, compressed crowns, with a nearly straight or slightly concave free cutting edge, both outer and inner surfaces usually marked by a series of parallel, vertical grooves and ridges. Molars with quadrate crowns, having a blunt, conical cusp at each corner, the fourth notably smaller than the third, sometimes rudimentary or absent. Fore feet narrow; three middle toes considerably exceeding the first and fifth in length; their claws long, compressed, and but slightly curved. Hind feet as in Macropus. Tail long, sometimes partially prehensile, being used for carrying bundles of grass with which they build their nests.

The potoroos or rat-kangaroos are all small animals, none of them exceeding a common rabbit in size. They inhabit Australia and Tasmania, are nocturnal, and feed on the leaves of various kinds of grasses and other plants, as well as roots and bulbs, which they dig up with their fore paws. About ten species are known, presenting a considerable range of diversity in minor characters, and admitting of being grouped in four principal sections, which may perhaps be allowed the rank of genera. These are.

1. Hypsiprymnus, Illiger. – Head long and slender. Auditory bullae somewhat inflated. Ridges on premolars few and perpendicular. Large platine foramina. Tarsus short. Muffle naked. H. murinus, H. apicalis, H. gilberti, h. platyops.

2. Bettongia, Gray. Head comparatively short and broad. Auditory bullae much inflated. Tarsus long. Large palatine foramina. Ridges on premolars numerous and oblique. Muffle naked. B. penicillatus, B. cuniculus B. gaimardii, B. ogilbyi, B. grayii, B. campestris, &c.

3. Aepyprymnus, Garrod. – Head short and broad. Auditory bullae not inflated. No palatine foramina. Tarsus long. Muddle hairy. AE rufescens.

4. Hypsiprymnodon, Pierson-Ramsayt- distinguished from all other members of the family by possessing a small prehensile hallux or first toe, without nail. It is, therefore, a form of great interest, as showing a structure of foot connecting that of the kangaroos with that of the phalangers. The single known species, H. moschatus, Ramsay, has been lately discovered in north-east Australia. It was described almost simultaneously by Owen under the name of Pleopus nudicaudatus.

In seeking among the other marsupials for the nearest allies to the kangaroos using this word in the comprehensive sense as above, two most striking points in their organization must be borne in mind, the structure of the hind foot and the dentition. Of the former the essential peculiarity is the great predominance of the fourth digit, and the remarkable character of the second and third, which while retaining a considerable length, are of extreme tenuity, and buried up to the claws in a common integument. Such a structure of foot is quite unknown out of the marsupial order, but in that order it is found in the Phalangistidae in a very modified form, associated with a large opposable hallux, and a broad sole of the foot, appropriate for climbing trees; and again, in almost the same form as in the kangaroos, in the ground –dwelling Peramelidae, which in their dentition and digestive organs are so widely different. The Australian carnivorous marsupials, Dasyuridae, and the American opossums or Didelphidae, show no trace of this singular conformation. It is therefore only with the former families, the Phalangistidae and the Peramelidae, that the kangaroos are allied by this character.

The chief peculiarity of the dentition consists in the presence of three pairs of incisors in the upper jaw, the first or middle one of which is generally the largest, opposed to a single pair in the lower jaw, strong, sharp, and procumbent. These are followed by an interval, in which may be, in the upper jaw only, a canine, but always so small, as to be of little functional importance. The premolars are compressed and cutting, and the true molars ridged or tuberculated. Such a dentition is found among the Phalangistidae alone of existing marsupials. In this respect the Peramelidae are completely separated from the kangaroos, their numerous small incisors, large canines, and cuspidated molars resembling those of the Dasyuridae and Didelphidae. On the whole then, the kangaroos and the phalangers are groups most nearly allied in essential characters, having both dentition and extremities formed upon the same fundamental type, though with modifications of the latter to suit their respective terrestrial and arboreal habits.

Remains of numerous extinct species of true kangaroos, many of them of much larger size than any now existing, are abundant in the Pleistocene deposits of Australia, and have been described and figured by Professor Owen in the Philosophical Transactions. Hitherto they have been found in no other part of the world. Other animals of gigantic size, the Diprotodon, as large as a rhinoceros, and the Nototherium, but little inferior, with dentition of the same general type, but the structure of whose feet is not yet known, lived with these kangaroos in the same land. An extraordinary modification of the Hypsiorymnus type, with the great premolar characteristic of that genus immensely exaggerated in size, and the true molars equally reduced, misnamed Thylacoleo carnifex, was another contemporary. Beyond these, which all belong to the most recent geological epoch, we have to knowledge of any extinct animals which can be said to be nearly allied to kangaroos, or to connect them with any other forms of mammals. The only marsupials discovered in European Tertiaries resemble the existing opossums of America, and except in their common marsupial character have no affinities with the kangaroos.

It is, however, a most remarkable fact that in the Purbeck beds of the nevr Oolitic series, not only in England, but also in deposits of corresponding age in America, lower jaws of small mammals (to which Dr Falconer gave the name of Plagiaulax), with a type of dentition showing a considerable resemblance to that described above as peculiar to the kangaroos and their existing allies, have been discovered. Unfortunately no part of the skull or upper teeth, or of the limbs of any of these is as yet known; so whether the resemblance was fully carried out, even in the dentition, is uncertain, and it is almost too great a stretch of the imagination to assume that the modern "diprotodont" marsupials have derived their special type of tooth structure from such remote ancestry. The evidence of the affinity of the still more ancient Hypsiprymuopsis (Boyd Dawkins), founded upon a single and much worn tooth, having some resemblance to one of the large premolars of Hypsiprymnus, found in the infra-Liassic beds of Watchet in Somersetshire, is based on still slighter foundation; but, if it should eventually turn out to be well-grounded, it would carry back the type to an extraordinary antiquity.

Literature. – G.R. Waterhouse, Nat. Hist. f the Mammalia, vol. i. "Marsupiata," 1846; J. Gould, Mammals of Australia; R. Owe, article "Marsupialia" in Cyclop. Of Anatomy and Physiology; various memoirs "On Extinct Mammals of Australia" in Philosophical Transactions; "Mesozoic Mammalia," Palaeontographical Society, 1871; H. Falconer, "On Plagiaulax," Quart. Journ. Goel. Soc. August 1857 and November 1862; W.H. Flower, "On the Development and Succession of the Teeth in the marsupialia, "Phil, Trans., 1867; "On the Affinities and Probable Habits of Thylacoleo," Quart, Journ, Geol.Soc., August, 1868; A.H. Garrod, "On Dorcopsis luctuosa and its Affinities," Proc. Zool. Soc., 1875, p. 48. (W.H.F.)

The above article was written by Sir William Henry Flower, K.C.B., D.Sc, D.C.L., LL.D., Ph.D., F.R.S.; Director of British Museum, Natural History Department; President of the Zoological Society; President of the British Association, 1889; author of Introduction to the Osteology of Mammalia and The Horse: a Study in Natural History.

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