Raiders of the Lost Arc

The "Flicks on the Bricks" series at Portland Pioneer Square, showing a movie on Friday night on a giant inflatable screen at dusk, with "Raiders of the Lost Ark"...

... the presenter (a dj from a light rock radio station, apparently) rolled through the trivia, and mentioned (probably through a google search, and indeed a google search shows the words she used precisely-- ie: George Lucas was 15 and Steven Spielberg was 12) that the opening sequence came out of a Carl Barks - created Donald Duck comic book -- "Prize of Pizarro". (Further allusions can be made with "The Seven Cities of Cibola".)

Adapted into the tv cartoon "Duck Tales", and thus engrained in my memory is the image of a giant boulder chasing Scrooge McDuck and Huey Duey and Luey and the character created for the show whom I don't remember a name for. (Doofus?)