This lifeform is found in Australia.

Rock Wallaby (Petrogale penicillata) is sensitive to disturbances of its habitat. It appears to be endangered and is perhaps declining over most of its range. The Rock Wallaby lives in colonies in scarps, rocky areas, of southeastern Australia. They venture out in the late afternoon and evenings and sleep during the day. Well-worn paths among stony areas give away their habitat.
                      
Yellow-footed Rock Wallaby (Petrogale xanthopus)(also known as the ring-tailed rock wallaby) has been extensively hunted for their pelts and appear to be endangered. They have striking marks of yellow and brown rings on their tails, yellow ear-backs and brightly colored feet. This small marsupial is a social animal and lives in colonies. Although capable of great speed and daring leaps they are slow to become alarmed. In addition to the threat of man, they must compete with goats for forage and shelter and are subject to attack by foxes, wild dogs and snakes. While once plentiful in South Australia, they are now making a last stand on the New South Wales border. They are protected in South Australia.

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.