This lifeform is found in Australia. This lifeform is widespread, but not common.
Red Kangaroo (Macropus rufa; Megaleia rufa), have extensively been hunted for their skins to the point that their populations have declined in some areas although their numbers have increased in others. They are perhaps the largest of the living kangaroos and are best adapted to the grassy savannas of western Australia. The Red Kangaroo is a grazing ungulate (hoofed mammal) and represents the final stage of herbivorous evolution. They are excellent sprinters and jumpers. Their speed can reach approximately 80 km/hour; their jumping distance is approximately nine meters. But they tire easily over long distances. There is evidence they are threatened by hunting. They have received various measures of protection.
Macropus genus, kangaroos and wallabies, contains 14 different species including the red kangaroo, the eastern gray kangaroo, and the blackfaced kangaroo. This genus also contains several species of wallabies. Members of this genus are found in Australia and New Guinea.
Kangaroos and Wallabies (Macropodidae Family) with over seventy species form a family that includes a range of species differing widely in appearance and habits. Some species are the size of rats; others may be as large as four feet tall. The marsupial pouch opens forward and is well-developed. There are five digits on the shorter forearms and usually no first digit on the hind limbs which can be relatively long. Members of this family may be found in Australia, New Guinea, Tasmania and surrounding islands.
Wallabia represents a group that differs from the kangaroo genus Macropus by its smaller size. Wallabies generally live on open plains where they can find shelter in shrubs or under trees while visiting the open areas only to graze late in the day or early mornings. Considered competitors of sheep and cattle, they are hunted and provide meat for dog food and some are considered excellent for the fur trade. They are an element of Australia's typical kangaroo community.
Marsupials (Order Marsupiala) are a very ancient group of mammals that emerged at the end of the Mesozoic. They are the original mammalian fauna of the Australian region where most of this order are found. They are more advanced than the monotremes, differing in anatomy and physiology as well as in the fact that they give birth to young formed within the mother's body (viviparous). Members are characterized by having a pouch to hold the newly born underdeveloped young.
This group of mammals is unusual in that it contains a great variety of forms. There are mouselike animals, kangaroos, the familiar opossum, a wolf-like creature (Tasmanian Wolf, seemingly recently extinct), and an unusual creature called the Tasmanian Devil that has habits like a primitive carnivore.
Marsupials contain examples of a biological theory called convergent evolution. The fact that the Marsupials could develop a wolf-like creature very similar in habits and shape to the North American wolf shows that certain life forms are stable in certain environments.
Several prehistoric marsupials are worthy of mention. The Thylacosmilus genus of South America contained a large species of cat-like carnivore that looked like a saber-toothed tiger and was the size of a jaguar. Thylacoleo was a marsupial lion that became extinct perhaps just 40,000 years ago.
Mammals (Class Mammalia), together with the birds, are among the youngest of the classes of animals. In species count, mammals number about fifty-one hundred, trailing reptiles (approximately fifty-five hundred), fish (approximately eighteen thousand), and birds (approximately eighty-six hundred).
There are three sub-types of mammals:
monotremes, the most primitive:
Develop in reptilian-like eggs and suckle milk emerging
(i.e., spiny anteater, duckbilled platypus)
marsupials
Newborn emerges very underdeveloped and continue to
mature in a pouch on its mother's abdomen (i.e., opossums,
koala, kangaroo)
placental
Embryo develops within the uterus of the female and is
dependent on a placenta for nutrition and waste removal
(i.e., humans, lions, monkeys)
About sixty-five million years ago, the Tertiary era produced thirty-five orders of mammals. Of this number, eighteen have survived to represent Earth's most diversified as well as its most highly developed classification of animals.
Extinction of mammals is fast becoming a serious issue. Duff and Lawson present a list of forty-one extinct species that reached extinction prior to 1800. These forty-one species are not acknowledged in the counts of the various families. Duff and Lawson also present a list of forty-six species including three gazelles, one zebra, one seal, one deer, and one wolf that have probably gone extinct since 1800. These forty-six species are included in the family counts. Science is adding about forty to fifty new species a year to the list. Many of these are the result of divisions of prior species; some are recent discoveries.
Mammals owe their survival to adaptive capabilities that include the ability to exploit whatever sources of food are available to them, as well as their ability to adjust to various climes. Food specialization influenced evolution to such a great extent that the teeth structure can and has been used to provide extensive information on the food needs and various lifestyles of extinct species.
Despite the vast diversity among mammals in terms of size, habitats and adaptations, they share without exception many characteristics such as:
a. body hair
b. mammary glands
c. certain skull characteristics
d. four limbs that permit speed
e. parallel not perpendicular limbs
f. compartmentalized internal organs
g. a four-chambered heart and pulmonary circulation
Backboned Animals (Phylum Chordata) are the most advanced group of animals on earth. These animals are characterized by having a spinal cord or backbone. Most members have a clearly defined brain that controls the organism through a spinal cord. Fish, amphibians, reptiles, birds, and mammals are in this phylum.
Currently, some taxonomists believe that the fish should be divided into two groups (sharks and regular fishes) and that there are some other primitive groups in the phylum such as hagfish or lampreys.
Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.