This lifeform is found in Australia. This lifeform is rare.

Duck Billed Platypus (Ornithorhynchus anatinus) is a primitive mammal and one of several that lay eggs. Found in southeastern Australia and Tasmania, it is about twenty-two inches long (including the long flattened tail). It lives in burrows along the edge of bodies of water and dives for food that includes aquatic insects, mollusks, and other small animals. Its duck-like muzzle has adapted well to this purpose. It is one of only a few mammals that is poisonous. The poison on the horny spur of the heel of the male can kill small mammals and cause great pain to a human.

Monotremes (Monotremata Order). Archaeologists who study extinct primitive mammals divide them into two groups: Protherians and Therians.

Of the once giant group of Protherians, it is felt by many experts that the Monotremes are the only surviving members. Examples of this order are found solely in Australia, neighboring New Guinea, and Tasmania. The similarity of the extant (non-extinct) Monotremes and the ancient members of the Protherian group is very high. It has recently been proposed that the Monotremes may really be an ancient offshoot of a few selected Marsupials.

For further study of this complex issue refer to "Mesozoic Mammals," edited by Jason A. Lillegraven, Zofia Kielan-Jaworowska, and William A. Clemens published by University of California Press at Berkley. Chapter 15 by William Clemems discusses this issue.

The two types of Monotremes are: Echidna (spiny ant-eaters) and Ornithorhynchus (platypus). There are four species of echidnas and one species of platypus.

The spiny ant-eaters are found in New Guinea, Tasmania and Australia. Very much resembling the hedgehog, the name is derived from their tapering snout. Their tongues are very thin; rather than teeth they have warts that act as food grinders.

The platypus is a burrowing animal that lives singly or in pairs. It's name is derived from its duck-like bill. It has webbed feet and thick brown fur. Its triple reptilian eyelid is located on the side of its head. The young suckle the fur of the mother from whose mammary area milk trickles through small pores. The platypus is very much at home in and spends a great deal of its time in the water.

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.