The Marsupial has always been a strong prominent type of mammal species, existing now after millions of years of struggle and a fight for existence. Marsupials have overcome the invasion of other mammals (specifically placentals during the Mesozoic period), the splitting of continents, (see plate tectonics) which led to a whole new environment and way of life for them, and as well the adoption to new physical characteristics to survive in their new environment.

The continents of Australia and South America have both been able to nourish and sustain a living environment for millions of years, enough of a time to keep the Marsupial fauna going until present time. The first marsupials appeared in North America during the Mesozoic period (link) and were as well more popular than placental mammals. It wasn’t until the end of the Cretaceous period that Marsupials began to populate over South America. Due to the Eocene period, placentals were now unable to cross over to South America and invade the life of the Marsupials. The Marsupial fauna was then able to come in contact with Antarctica, which at the time was attached to South America and Australia. They then moved on to a land of vegetation found in Australia. The Miocene period allowed Marsupials to remain in Australia without fear of having an invasion from the placental species.

The Marsupial species has not only survived stages of conflict throughout millions of years but has managed to sustain a comprise of about 272 species and are today, the most dominant mammals known in Australia. According to The Encyclopedia of Mammals, it has been researched and recorded that there have been and probably still are around 19 main Marsupial families, these families stretch out to the infamous Koalas and Kangaroos to the rarely heard about and nectar eating Gliding Phalangers. Even though many scientists give evidential numbers to the species and families, it is suspicion that there are Marsupial species out in the world that are yet to be explored and classified. It is difficult, for their living habits have made it impossible for scientists to spot and explore them.

Due to the splitting of the continents that ocurred millions of years ago, the majority of marsupials were isolated in South America and Australia. One of the main Marsupial Mammals that can be found in Australia then and today is the Kangaroo. The Kangaroo is one of the world’s mammal that looks like no other. The most noticed factor of a kangaroo is it’s front pouch used for nourishing its young. This abdominal pouch is used for carrying around the new born young, Joey, until it is ready to be on its own. The Joey finds its way to the pouch without the help of its mother and stays there until it is five to nine months, depending on the species of the Kangaroo. The Kangaroo emerges permanently when it is 6-10 months of age, and stays inside its mother‘s pouch until it reaches the age of 12-18 months.

Kangaroos vary in size, the color and texture of their fur, and as well vary in the way they live. The largest is the Red Kangaroo. It stands taller than a man and can weigh up to 85 kgs. It is the largest marsupial known to man in the world.An adult Kangaroo usually has the characteristics consisting of, sheep like heads, large movable ears, with a slender chest. This specific type of Kangaroo has an immense amount of strength used for protection and defense against other mammals.

The large species of Kangaroos usually rests in the shade during the day and come out to eat in the late afternoon and during the night when it is much cooler. They eat mostly grass that they find in the fields. They need very little water to survive and can survive without drinking for months. When it comes to their young, they feed milk to them even when it is quite large, through the teats that they have inside of their abdominal pouch

Kangaroos as well range in smaller sizes, such as the size of a rabbit. These type of Kangaroo species are called wallabies. Wallabies range from Rock-wallabies which live on cliffs, boulder falls, or rock piles to the Large Red-Eyed Forest wallaby which lives the majority of its time on rainforest floor. These two specific wallabies are described by man to be more handsome and attractive than Red or Gray Kangaroos. Rock wallabies tend to be nocturnal and their way of nourishing their young resembles that of a regular Kangaroo would. Surprisingly, most young come out to weigh one gram at birth.

Kangaroos have differences in the way they live, where they live, and what they look like physically, but all Kangaroos share the way they nourish and look out for their young, and have similar choices in what they eat, being mostly grasses.

A Koalas life span today varies considerably due to stress factors, probably averaging 13-18 years. Koalas don't live in families, but are solitary animals. They sleep as long as 18 hours a day and have a low-energy diet of eucalyptus leaves. Although koalas obtain most of their water from leaves they do occasionally drink water at the edges of streams. It is presently known that one of their principal predator happens to be humans.