Kakapo relative wing size of any parrot. Its wing feathers are shorter, more rounded, less asymmetrical, and have fewer distal barbules to lock the feathers together. The sternum is small and has a low, vestigial keel and a shortened spina externa. As in other flightless birds and some flighted parrots, the furcula is not fused but consists of a pair of clavicles lying in contact with each coracoid. As in other flightless birds, the angle between the coracoid and sternum is enlarged. The kakapo has a larger pelvis than other parrots. The proximal bones of the leg and arm are disproportionately
Flightless bird oceanic islands. Incongruences between ratite phylogeny and Gondwana geological history indicate the presence of ratites in their current locations is the result of a secondary invasion by flying birds. It remains possible that the most recent common ancestor of ratites was flightless and the tinamou regained the ability to fly However, it is believed that the loss of flight is an easier transition for birds rather than the loss and regain of flight, which has never been documented in avian history. Moreover, tinamou nesting within flightless ratites indicates ancestral ratites were volant and multiple losses of flight occurred independently throughout