His eldest son, Anthony Avildsen,confirmed the newsto the Associated Press.
He was a pretty extraordinary man in my estimation, he said.
The 1976 film, which Stallone wrote, also claimed Oscars for best picture and editing.

Credit: Matt Winkelmeyer/Getty Images
Though it proved to be a huge hit, Avildsen wasnt sold on the project at first.
When this script came to me from an old friend …
He pleaded and pleaded, so I finally read the thing.
And on the second or third page, hes talking to his turtles, Cuff and Link.
And I said yes.
Avildsen is also the subject of the upcoming documentaryJohn G. Avildsen: King of the Underdogs.