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
Koala the middle to late Pleistocene, and possibly as early as the Pliocene. The fossil record of the modern koala extends back at least to the middle Pleistocene. Traditionally, three distinct subspecies have been recognised: the Queensland koala ("P. c. adustus", Thomas 1923), the New South Wales koala ("P. c. cinereus", Goldfuss 1817), and the Victorian koala ("P. c. victor", Troughton 1935). These forms are distinguished by pelage colour and thickness, body size, and skull shape. The Queensland koala is the smallest of the three, with shorter, silver fur and a shorter skull. The Victorian koala is the largest, with shaggier,