Diplodocus is a dinosaur that lived 150-145 million years ago during the late Jurassic period. It was a character in Disney's 1940 film Fantasia appearing in The Rite of Spring segment.
A 30 minute short film where after the animators at Disney Studios leave for the day, suddenly Mickey and Minnie jump out of the pictures and round up all the animated Disney characters in history for one giant group photo after 100 years.