|Billions of years ago - Millions of years ago - Thousands of years ago - 1st century|
- c. 252,000,000 BC
- The Permian-Triassic Extinction Event occurs on Earth, causing up to 90% of Earth's species to disappear from the fossil record. 
- c. 250,000,000–100,000,000 BC
- The Manraloth try to forcibly "ascend" all intelligent life in the galaxy to a higher plane of existence. This results in there being no evidence of intelligent life during this period.
- c. 99,998,000 BC–998,000 BC
- The Rigellian Masters are the fourth civilization to rise on Rigel IV. Their empire conquers much of the Orion Arm, engages in stellar and planetary engineering in the Rigel system and creates the Rigellians before they finally die out.
- 65 million years ago
- Dinosaurs go extinct.
- 11 million years ago
- The first recognizable whales appeared from the evolution process on Earth. 
- 4 million years ago
- The Class R planet Cybertron drifts towards the sol asteroid belt. To save their home, the Autobots blast a path through the rocks but are attacked by Decepticons. Both parties crash onto Earth, winding up in stasis lock until the 1980s.
- Before 1m years ago
- Miscellaneous unclassified traces in Kridnar. An unidentified culture makes an appearance, code EO-522. Probable T'kon visits, and possibly Age of Xora.
- 1 million years ago
- According to traces of habitation found on worlds incapable of supporting life, interstellar travel was commonplace a million or more years before the 23rd century.
- 1,000,000 BC
- The humanoid creators of the Robots and the Master Computer abandon their creations, leaving them to fend for themselves. The Robots eventually learn to build new generations of their kind. 
References and notes
- TNG - The Lost Era novel: The Buried Age.
- FASA RPG - The Orions modules: Book of Common Knowledge, Book of Deep Knowledge.
- Last Unicorn RPG module: All Our Yesterdays: The Time Travel Sourcebook.
- TOS novelization: Star Trek IV: The Voyage Home.
- TAS comic: "Star Trek vs. Transformers, Issue 2"
- TNG video game: A Final Unity.
- FASA RPG - The Orions module: Book of Common Knowledge.
- TOS comic: "Life Form Nonexistent".
Chapters 12, 17, 19 & 23
|The Original Series||64,018,143 BC||novel|