KANGAROO, the universally accepted, though not
apparently the native, designation of the more typical
representatives of the marsupial family
Macropodidae (see
Marsupialia).
Although intimately connected with the cuscuses and phalangers by
means of the
musk-kangaroo, the
kangaroos and wallabies, together with the
rat-kangaroos, are easily distinguishable from
other diprotodont marsupials 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 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 give the animals 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 animals 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 two hind-legs to form a
tripod, and the front-limbs dangling by the side
of the
chest. This position
gives full scope for the senses of sight,
hearing and
smell to warn of the approach of enemies. The
fore-paws have five digits, each armed with a strong, curved claw.
The hind-foot is extremely long, narrow and (except in the
musk-kangaroo) without the first toe. It consists mainly of one
very large and strong toe, corresponding to the fourth of the human
foot, ending in a strong curved and pointed claw (fig. 2). Close to
the outer side of this lies a smaller fifth
digit, and to the inner side two excessively
slender toes (the second and third), bound together almost to the
extremity in a common
FIG. 1. - The Great Grey
Kangaroo (
Macropus giganteus). 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 connexion with the functions of support or progression.
This type
of foot-structure is termed
syndactylous.
The dental formula, when completely developed, is
incisors
i, canines o, premolars 31 molars - on each side, giving a
total of 34 teeth. The three incisors of the upper
jaw are arranged in a continuous arched series, and
have crowns with broad 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, which is of great size,
directed horizontally forwards, narrow, lanceolate and pointed with
sharp edges. Owing to the slight union of the two halves of the
lower jaw in front in many species the two lower incisors work
together like the blades of a pair of
scissors. The canines are absent or
rudimentary in the lower, and often
deciduous at an early age in the upper jaw.
The first two premolars are compressed, with cutting longitudinal
edges, the anterior one is deciduous, being lost about the time the
second one replaces the
milk-molar, so that three premolars are never
found in place and use in the same individual. The last premolar
and the molars have quadrate crowns, provided with two strong
transverse ridges, or with four obtuse cusps. In
Macropus
giganteus and its immediate allies, the premolars and
sometimes the first molar are
shed, 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 to a single
tooth on each side of each jaw, the other molars and incisors being
never changed. The dentition of the kangaroos, functionally
considered, thus consists of sharp-edged incisors, most developed
near the median line of the mouth, for the purpose of cropping
herbage, and ridged or tuberculated molars for crushing.
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
fore-paw. 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 large and
very complex, its walls being puckered by longitudinal muscular
bands into a number of folds. The
alimentary canal is long, and the
caecum well developed. The young (which, as in other marsupials,
leave the uterus in an extremely small and imperfect condition) are
placed in the pouch as soon as they are born; and to this they
resort temporarily for shelter for some time after they are able to
run, jump and feed upon the 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 of 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 existence the elongated upper part of the larynx
projects into the posterior nares, and so maintains a free
communication between the lungs and the external surface,
independently of the mouth and gullet, thus averting danger of
suffocation while the milk is passing down the gullet.
Kangaroos are
vegetable-feeders, browsing on
grass
and various kinds of herbage, but the smaller species also eat
FIG. 3. -
Skull and teeth of
Bennett's
Wallaby
(
Macropus ruficollis bennettii): i l , i 2, i 3, first,
second and third upper incisors; pm, second premolar (the first
having been already shed); m l, m 2, m 3, m4, last premolar and
three molars. The last, not fully developed, is nearly concealed by
the ascending part of the lower jaw.
roots. They are naturally timid and inoffensive, but the larger
kinds 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, supporting themselves meanwhile
upon the tail. The majority are inhabitants of
Australia and
Tasmania, forming one of the most prominent
and characteristic features of the
fauna of these lands, and performing the part of
the
deer and antelopes of other
parts of the world.
.^ One Australian team has even suggested we wean ourselves from cattle and sheep altogether and eat kangaroo instead - they do not emit methane.- How kangaroo burgers could save the planet - environment - 25 December 2008 - New Scientist 14 January 2010 4:04 UTC www.newscientist.com [Source type: General]
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 occurs.
The more typical representatives of the group constitute the
subfamily Macropodinae, in which the cutting-edges of the
upper incisors are nearly level, or the first pair but slightly
longer than the others (fig. 3). The canines are rudimentary and
often wanting. The molars are usually not longer (from before
backwards) than the anterior premolars, and less compressed than in
the next section. The crowns of the molars have two prominent
transverse ridges. The fore-limbs 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.
FIG. 2. -
Skeleton of
right hindfoot of Kangaroo.
The typical genus
Macropus, in which the muzzle is
generally naked, the ears large, the fur on the nape of the neck
usually directed backwards, the claw of the fourth hind-toe very
large, and the tail stout and tapering, includes a large number of
species. Among these, the great grey kangaroo (
M.
giganteus, fig. i) deserves special mention on account of
having been discovered during Captain Cook's first voyage in 1770.
The great red kangaroo (
M. rufus) is about the same size,
while other large species are
M. antilopinus and
M.
robustus. The larger wallabies, or
brush-kangaroos, such as the red-necked wallaby
(
M. ruficollis) constitute a group of smallersized
species; while the smaller wallabies, such as the
filander (
M.
muelleri) and
M. thetidis, constitute yet another
section.
.^ Under new owners, and with skipper Gus Mere in charge, ran aground in Windmill Bay, under Cape Willoughby, eastern tip of Kangaroo Island.
Nearly allied are the rock-wallabies of Australia and Tasmania,
constituting the genus
Petrogale, chiefly distinguished by
the thinner tail being more densely haired and terminating in a
tuff. Wellknown species are
P.
penicillata, P. xanthopus and
P. lateralis. The few
species of
nail-tailed wallabies,
Onychogale, which are confined to the Australian mainland,
take their name from the presence of a horny
spur at the end of the tail, and are further
distinguished by the hairy muzzle.
0. unguifer, 0.
fraenatus and
0. lunatus represent the group. The
hare-wallabies, such as
Lagorchestes leporoides, L. hirsutus and
L.
consepicillatus, constitute a genus with the same distribution
as the last, and likewise with a hairy muzzle, but with a rather
short, evenly furred tail, devoid of a spur. They are great leapers
and
swift runners, mostly
frequenting open stony plains.
More distinct is the Papuan genus Dorcopsis, as
typified by D. muelleri, although it is to some extent
connected with Macropus by D. macleyi. The muzzle
is naked, the fur on the nape of the neck directed more or less
completely forward, and the hind-limbs are less
disproportionately elongated. Perhaps, however, the most Fig. 4. -
Skull and teeth of Lesueuir's Rat-Kangaroo (Bettongia
lesueuiri). c, upper canine. Other letters as in fig. 3. The
anterior premolar has been shed.
distinctive feature of the genus is the great fore-and-aft
length of the penultimate premolar in both jaws. Other species are
D. rufolateralis and
D. aurantiacus. In the
tree-kangaroos, which include the
Papuan
Dendrolagus inustus, D. ursinus, D. dorianus, D.
benetianus and
D. maximus, and the North
Queensland D.
lumholtzi, the reduction in the length of the hind-limbs is
carried to a still further degree, so that the proportions of the
fore and hind limbs are almost normal. The genus agrees with
Dorcopsis in the direction of the hair on the neck, but
the muzzle
is only partially hairy, and the
elongation of the
penultimate premolar is less. These kangaroos are largely arboreal
in their habits, but they descend to the ground to feed. Lastly, we
have the banded wallaby,
Lagostrophus fasciatus, of
Western
Australia, a small species characterized by its naked muzzle,
the presence of long bristles on the hindfeet which conceal the
claws, and also of dark transverse bands on the lower part of the
back. The skull has a remarkably narrow and pointed muzzle and much
inflated auditory bullae; while the two halves of the lower jaw are
firmly welded together at their junction, thus effectually
preventing the scissor-like action of the lower incisors
distinctive of
Macropus and its immediate allies. As
regards the teeth, canines are wanting, and the penultimate upper
premolar is short, from before backwards, with a distinct ledge on
the inner side.
.^ Also organic, more or less by definition - they're hunted, not grown (there's a serious surplus of roos in Australia).- How kangaroo burgers could save the planet - environment - 25 December 2008 - New Scientist 14 January 2010 4:04 UTC www.newscientist.com [Source type: General]
^ How exactly will viewers benefit from other VOD services - all of which are subscription based - rather than the free ad-supported offering from Kangaroo?- Project Kangaroo blocked by Competition Commission | Media | guardian.co.uk 14 January 2010 4:04 UTC www.guardian.co.uk [Source type: News]
Molars with quadrate crowns and a blunt conical
cusp at each corner, the last notably
smaller than the rest, sometimes rudimentary or absent. Forefeet
narrow; the three middle toes considerably exceeding the first and
fifth in length and their claws long, compressed and but slightly
curved. Hind-feet as in
Macropus. Tail long, and sometimes
partially prehensile when it is used for carrying bundles of grass
with which these animals build their nests. The group is confined
to Australia and Tasmania, and all the species are relatively
small.
In the members of the typical genus
Potorous (formerly
known as
Hypsiprymnus) the head is long and slender, with
the auditory bullae somewhat swollen; while the ridges on the first
two premolars are few and perpendicular, and there are large
vacuities on the
palate. The
tarsus is short and the muzzle
naked. The genus includes
P. tridactylus, P. gilberti and
P. platyops. In
Bettongia, on the other hand, the
head is shorter and wider, with smaller and more rounded ears, and
more swollen auditory bullae. The ridges on the first two premolars
are also more numerous and somewhat oblique (fig. 4); the tarsus is
long and the tail is prehensile. The species include
B.
lesueuiri, B. gaimardi and
B. cuniculus. The South
Australian
Caloprymnus campestris represents a genus near
akin to the last, but with the edge of the hairy border of the bare
muzzle less emarginate in the middle line, still more swollen
auditory bullae, very large and posterially expanded nasals and
longer vacuities on the palate. The list is completed by
Aepyprymnus rufescens, which differs from all the others
by the hairy muzzle, and the absence of inflation in the auditory
bullae and of vacuities in the palate.
.^ Ashore in strong winds, a few miles north east from Kingscote, Kangaroo Island, 15 May 1884.
^ Wrecked ashore, north east of Cape St. Albans on Kangaroo Island, 3 March 1976.
.^ I think it very remiss of NS to make methane sound like it is the real problem, without at least some mention of these other considerations.- How kangaroo burgers could save the planet - environment - 25 December 2008 - New Scientist 14 January 2010 4:04 UTC www.newscientist.com [Source type: General]
(W. H. F.; R. L.*)