Fauna of Australia in Australia, feeding on sea grass in coastal areas. The destruction of sea grass beds is a threat to the survival of this species. Eleven species of seal—family Pinnipedia—live off the southern coast. Australia and its territories are home to around 800 species of bird; 45% of these are endemic to Australia. The fossil record of birds in Australia is patchy; however, there are records of the ancestors of contemporary species as early as the Late Oligocene. Birds with a Gondwanan history include the flightless ratites (the emu and southern cassowary), megapodes (the malleefowl and Australian brush-turkey), and a huge
Bird feet and legs absent in diving birds. For example, in the long-tailed duck, the leg and wing bones are not pneumatic, in contrast with some of the other bones, while loonsand puffins have even more massive skeletons with no aired bones. The flightless ostrich and emu have pneumatic femurs, and so far this is the only known pneumatic bone in these birds except for the ostrich's cervical vertebrae. Fusions (leading to rigidity) and pneumatic bones (leading to reduced mass) are some of the many adaptations of birds for flight. Most birds, except loons and grebes, are digitigrade, not plantigrade. Also, chicks in the