Marsupial

“ We had a glimpse of the museum, by courtesy of the American gentleman who is curator of it. It has samples of half-a-dozen different kinds of marsupials— [A marsupial is a plantigrade vertebrate whose specialty is its pocket. In some countries it is extinct, in the others it is rare. The first American marsupials were Stephen Girard, Mr. Astor and the opossum; the principal marsupials of the Southern Hemisphere are Mr. Rhodes, and the kangaroo. I, myself, am the latest marsupial. Also, I might boast that I have the largest pocket of them all. But there is nothing in that.] ”

“ Among the characters which serve to distinguish the marsupials, there are two to which I have already called attention in describing the kangaroo; namely, the marsupial bones and the inflected angle of the lower jaw.
Every mammal which has marsupial bones has the angle of its jaw inflected, or else has no angle to its jaw at all; while every animal which has both marsupial bones and an inflected jaw-angle possesses also those special characters of the reproductive system which distinguish the marsupials from all other mammals. ”

“ This pair of little pits may be regarded as the beginning of the bilateral pocket so largely developed in some marsupials. If we can imagine that these depressions have become so deep as to envelop not only the nose of the young, but also its whole body, we can understand the evolution of a marsupial from something lower. ”

“ As this inferior condition of living Marsupialia shows this order to hold an intermediate place between viviparous and oviparous animals, forming, as it were, a link between Mammalia and Reptiles; the analogies afforded by the occurrence of the more simple forms of other classes of animals in the earlier geological deposites, would lead us to expect also that the first forms of Mammalia would have been Marsupial. ”

“ The last order of mammals is a very curious one, for in most of the animals which belong to it there is a large pouch on the lower part of the body of the female, in which she carries her little ones about for several weeks, or even several months, after they are born. That is why these creatures are called marsupials, for marsupial means pouched. Even after the little animals are quite able to take care of themselves they will hurry back to their mother and jump into her pouch in moments of danger. ”

“ Mammals belonging to quite different Orders show traces more or less marked of a marsupium. In young Dogs the teats are borne upon an area where the skin is thinner, the covering of hair less dense than elsewhere—all points of resemblance to the inside of the pouch of a Marsupial; in addition to this there are traces of the sphincter marsupii muscle. In other Carnivora there are similar vestiges. In Lemur catta a more complete rudiment of a marsupial pouch is to be met with. ”

“ It is an innocent and peaceful marsupial, which is active only at night, and sluggishly climbs the trees, eating leaves and sleeping during the whole day. As soon as the young has left the pouch, the mother carries it with her on her back. ”

“ The Duckbill lays its eggs just like the reptile, but provides a warm nest for them at the bottom of its burrow. The Anteater develops a temporary pouch in its body, when it lays an egg, and hatches the egg in it. The Marsupial retains the egg in its womb until the young is advanced in development, then transfers the young to the pouch, and forces milk into its mouth from its breasts. The real reason for this is that the Marsupial falls far short of the higher mammals in the structure of the womb, and cannot fully develop its young therein. ”

“ The very peculiar structure from which the Marsupial animals derive their name has been regarded by almost every naturalist who has written on the subject as so essential a deviation from the common type, that, setting aside all considerations of form or habits, and regardless even of those technical characters on which so much reliance is usually placed, they have for the most part agreed in uniting under the same family designation every animal in which it occurred. ”

“ See the Noun.
Marsupial, n. an animal in which the female has an abdominal pouch in which the young, born in a very immature state, are carried. (Lat. Marsupium = a pouch.) At the present day Marsupials are only found in America and the Australian region, the greater number being confined to the latter. See quotation 1894, Lydekker.
1848. W. Westgarth, `Australia Felix,' p. 129:
"The marsupial type exhibits the economy of nature under novel and very interesting arrangements. . . . Australia is the great head-quarters of the marsupial tribe." ”

“ This pouch is supported by two characteristic marsupial bones, also existing in Cloacal animals, but not in Placental animals. The young Marsupial animal is born in a much more imperfect form than the young Placental animal, and only attains the same degree of development which the latter possesses directly at its birth, after it has developed in the pouch for some time. ”

“ In standard works on natural history the animals under consideration are classed as mammiferous Didelphæ. They are brought forth in an imperfect state, and during their transitional condition are suckled in a pouch supported by bones called marsupial, which are attached by their extremities to the pelvis, and serve to support the marsupium, whence the animals provided with these provisions for bringing up their progeny are called Marsupial Mammals. The Opossum, Kangaroo, and Ornithorhynchus are existing representatives of this group. ”

“ Here, shut off from the severe competition experienced by the animals of northern lands, marsupials were modified so that they were adapted for life in almost every realm utilized by the higher mammals of other countries. Thus there are herbivorous, carnivorous, and insectivorous marsupials. Owing, probably, to the advent of Bats—true flying mammals—at, possibly, a comparatively early time, the marsupial was beaten in the air, and so a true flying form was not evolved, though the so-called "Flying Phalanger" is some distance on the way. ”

“ Many of the early mammals showed characters now found in the marsupials, the order to which the Kangaroo and Opossum belong, members of which are found in rocks of the Secondary Era, and are the only representatives of the mammalia in that age. Some of the early Eocene mammalia are either marsupials, or closely related to them. In the Oligocene we find the mammalian life becoming more varied, and branching out into the various groups we know to-day ”

“ We see, then, that the marsupials in a world of their own, cut off by the sea from the struggling world beyond, play all parts in life; and squirrels, monkeys, insect-eaters, gnawing animals, hoofed animals, and beasts of prey, all have their parallel among the pouch-bearers. But just because they are so isolated it becomes a curious question why, when we travel right across the wide Atlantic or Pacific to America, we find another set of pouched animals197 slightly different but belonging to the same group. ”

“ In the varied forms and functions they present, as beasts of prey, as grazers or root diggers, as ground-running, tree-climbing, burrowing or cave-haunting forms, some solitary and slow, others agile and gregarious, the marsupial tribe in its isolated corner of the earth exhibits an epitome of the whole mammalian world. It shows in a conspicuous way how the necessity and habit of making a living in [Pg 281] varied circumstances, and exposed to lively competition, restricting every species to a particular manner, brings about a suitable modification of structure. ”

“ Fig. 109.—Newborn young of Kangaroo.
It is very interesting to observe how, in Australia, where the Marsupials have been free from the competition of other mammals, they have evolved along many of the same general lines as the higher group. We have indeed no marsupial whales, bats, or seals, but there is a mole, very similar in its appearance and habits to our European species, and a carnivorous type which closely resembles a wolf or jackal; again we have bandicoots, occupying the same place in nature as our rabbits and other rodents ”

“ We have indeed far more clue to the relationship of the birds than we have of the marsupials, for while we have these reptile-like birds, we have also the bird-like reptiles such as the little Compsognathus, which hopped on two feet, had a long neck, bird-like head and many other bird-like characters, though no wings or feathers. ”

“ As we have no complete skeletons of these early mammals we must abstain from picturing their external appearance. It is enough that the living Monotreme and Marsupial so finely illustrate the transition from a reptilian to a mammalian form. There may have been types more primitive than the Duckbill, and others between the Duckbill and the Marsupial. ”

“ In many respects these marsupials evince a low organization, and really resemble, in their jaws and teeth, primitive mammals of ancient times discovered in fossil in Great Britain and North America. New Guinea also possesses some of these marsupial types, derived probably from Australia. ”

“ Mammalia have been found, as already stated, as far back as the Trias formation, in Europe in the United States and in South Africa, all being very small, and belonging either to the Marsupial order, or to some still lower and more generalised type, out of which both Marsupials and Insectivora were developed. ”

“ It is then clear that the Marsupials—viviparous Mammals without placenta—are a necessary transition from the oviparous Monotremes to the higher Placentals with chorion-villi. In this sense the Marsupial class certainly contains some of man’s ancestors. ”

“ Now everybody knows the marsupials as a class are nothing short of preternaturally stupid. They are just about the very dullest and silliest of all existing quadrupeds. And this is reasonable enough, when one comes to think of it, for they represent a very antique and early type, the first rough sketch of the mammalian idea, if I may so describe them, with wits unsharpened as yet by contact with the world in the fierce competition of the struggle for life as it displays itself on the crowded stage of the great continents. ”

“ For of course in the kingdom of science the last shall be first, and the first last; it is the oldest families that are accounted the worst, while the best families mean always the newest. Now, the earliest mammals to appear on earth were creatures of distinctly marsupial type. As long ago as the time when the red marl of Devonshire and the blue lias of Lyme Regis were laid down on the bed of the muddy sea that once covered the surface of Dorset and the English Channel, a little creature like the kangaroo rats of Southern Australia lived among the plains of what is now the south of England. ”

“ Returning now to our subject from this geological digression—which will hardly be deemed unprofitable, since I have given you in few words the results of a great deal of my own hard mountain work—let us consider the Tertiary mammals, as we know them front the remains already discovered, and attempt to trace the history of each order down to the present time. We have seen that a single small Marsupial, from the Trias, is the only mammal found in all the American rocks below the Eocene; and yet in beds of this age, immediately over the Chalk, fossil mammals of many different kinds abound. ”

“ Marsupials, in fact, are separated off from the rest of their class—from the great bulk of mammals—the Monodelphia—no less by their geographical limits than by their peculiarities of anatomical structure. ”

“ Hence, while the old-fashioned marsupials continued to survive and to evolve slowly along their own lines in their own restricted southern world, their collateral descendants in Europe and Asia and America or elsewhere went on progressing into far higher, stronger, and better adapted forms—the great central mammalian fauna. ”

“ Now, in the first place, very noticeable is the much greater diversity of structure found in the kangaroo's order than in any other order of mammals. While each of the latter is of one predominate type of structure and habit, we have found in the marsupials the greatest diversity in both.
Some marsupials are, we have seen, arboreal, some are burrowing, some flit through the air, while others range over and graze upon grassy plains. Some feed on vegetable food only, others are as exclusively insectivorous or carnivorous, and their teeth vary much in number and structure. ”

“ Marsupial bones unossified. The gradual passage of the thick root of the tail into the body is a character common to the Tasmanian wolf and the aard-vark, and may be directly inherited from reptilian ancestors (see Thylacine) . ”

“ The young of the Marsupials are brought forth, or born, in an imperfect condition, and undeveloped in size and strength. There are fossil remains of Marsupials showing that in past ages creatures of this kind existed which were as large as elephants. ”

“ The marsupials are a group of more primitive structure and greater antiquity than any which we have yet considered, so primitive, indeed, that they are referred to a separate infraclass, the Didelphia or Metatheria. ”

“ The order of living marsupials presents remarkable diversity of structure and habits, containing herbivorous, insectivorous, and carnivorous species; yet we find all these traits combined in one and the same species, the opossum. It is probable that, by adaptation to similar modes of life, the marsupials have developed groups parallel to those of the placental mammals. However, it is certain the Quadrumana seem represented by the Phalangers, the Carnivora by the Dasyuri, Insectivora by the Phascogales, Ruminantia by the kangaroos, and Edentata by the Monotremes. ”

“ The smaller types of marsupials of a hardier nature and capable of removing to greater distances for food, maintained their existence, while the giants of a similar race have left only their bones embedded in the drift to testify to the [Pg 242] mighty changes that Nature has wrought out in the past ages. ”