Short Stories, Long Timeline

2001: A Space Odyssey is broken into four distinct chapters that cover about 4 million years of history. These chapters are:

• The Dawn of Man
• The Untitled Second Section
• Jupiter Mission
• Jupiter and Beyond the Infinite

The chapters are mostly distinct stories connected by the mysterious monoliths as well as the film's themes and motifs. Although Dr. Floyd's message provides context for the Jupiter mission, it only appears at the end of that chapter. The conflict between HAL, Poole, and Bowman is a nearly self-contained story. Likewise, the appearance of the monolith connects Dawn of Man to the final story segment, but Dawn of Man can be seen as an independent story, as the hominids have their own character arcs. There's Caesar, and Koba, and…oh, sorry, wrong movie.

The film manages these story lines in a mostly traditional fashion. Each chapter is given a title card introducing audiences to the break between them. The exception to this rule is the second chapter.

Here, chapter transition isn't a title card but one of the most famous match cuts in cinematic history. When Moon-Watcher throws his bone club, the camera follows it spinning in the air. As it slowly falls back to earth, the picture suddenly cuts to a cylindrical satellite orbiting Earth, in a similar shape as the bone, moving the viewer 4 million years into the future.

If you were hoping for a narrative voice in the sky to help you put things together, you'll be disappointed. Kubrick often used voiceover narration and originally included it in 2001. Late in production, though, he cut the exposition from the film, sliding the difficultly level from challenging to hardcore mode. (Source)

No cheat sheets have been found to bring it back, either.