For one of the most copied musicians of the 20th century, it's pretty funny that "Ko-Ko" copies the chord changes of "Cherokee," a jazz standard by Ray Noble. Now, many songs have the same chord changes, but this was no accident. Bird himself has said that, with regards to "Cherokee," "[He] found that by using the higher intervals of a chord as a melody line and backing them with appropriately related changes, [he] could play the thing [he'd][/he] been hearing." In fact, he played the song so much that he couldn't stand it any more, even though he knew it in all 12 keys. Fortunately for Parker, you can't copyright chord changes, so he was free to improvise as he liked on top of them. From seemingly ceaseless experimentation over this chord progression came "Ko-Ko," the song you hear now.
What songs do you like that are based on other works?