Koala dominant. Older males usually have accumulated scratches, scars, and cuts on the exposed parts of their noses and on their eyelids. The koala's gestation period lasts 33–35 days, and a female gives birth to a single joey (although twins occur on occasion). As with all marsupials, the young are born while at the embryonic stage, weighing only . However, they have relatively well-developed lips, forelimbs, and shoulders, as well as functioning respiratory, digestive, and urinary systems. The joey crawls into its mother's pouch to continue the rest of its development. Unlike most other marsupials, the koala does not clean her
Giant koala two koala species co-existed during the Pleistocene, occupying the same arboreal niche. The reason for the extinction of the larger of the two about 50,000 years ago is unknown, although there are various hypotheses for the extinction. The giant koala is an arboreal marsupial weighing about twice as much as a koala, about 30 kg. It is known as the largest tree dwelling marsupial that has ever lived. Scientists say that there is a clear similarity in the physical appearance from the modern koala. It is assumed that the diet of the giant koala is eucalyptus leaves, and that the