File:Emu.PNG

Image in the public domain, as indicated on. Reason given is "This image is in the public domain because its copyright has expired. This applies to the European Union, Canada, the United States and those countries with a copyright term of life of the author plus 70 years."

Anyway, the point of the image is this, that wing is literally a vestigial stub, about the size of a human hand, and has quite literally no discernable usage at all whatsoever in any way.