Related Clues:

• Big differences
• Intervals
• Missing links?
• Hypothetical primates
• Spots in need of filling
• Halloween visitors, maybe
• Ancestors from long, long ago
• Pithecanthropine
• Sci-fi primates
• Alibi problems
• Interruptions
• They may be bridged
• Tarzan and kin
• Ancestors in Darwin's theory
• Zaius and Honorious, e.g.