h. 3,500,000,000 BC
City of Death
Scaroth, the last survivor of an advanced humanoid race called the Jagorath who had wiped themselves out in a huge war, crashed on primeval Earth. Attempting to take his ship to power three, warp thrust, he got too close to Earth's surface and his spaceship exploded over what would become the Atlantic Ocean. This somehow split him into twelve segments, which would later appear at various points in human history. [The interference of the last of these segments, the fourth Doctor, Romana, and a 1979 detective called Duggan may be responsible for this effect. The explosion acted as a catalyst for the primeval soup, which had formed to become simple life.
[Although the date is given by Scaroth and others as 400,000,000 BC, current evolutionary theory claims that life on Earth began c.3,500,000,000 BC and it had already begun by Venusian Lullaby. Hence, either the date or its connection to the creation of life on Earth is wrong. We've gone with the date being wrong.]
c. 3,000,000,000 BC
For three million years before this time, there had been a thriving civilisation on Venus. The Venusians were allergic to all metals except gold, platinum, and titanium. Despite this, their civilisation was highly developed, more so than those of many races without such weaknesses. But now Venus was dying. Most of its plant and animal life had gone and the majority of Venusians had accepted their fate. In some areas, Death Inspectors killed Venusians who had outlived their usefulness. A small number of Venusians tried to escape their fate. Thus such groups as the Magneteers, the Below the Sun Believers, the Magnetologists, the Water Breathers, the Rocketeers, the Cave Makers and the Volcano Makers had sprung up.
Following the death of Jofghil Dharkhig, Presidor of the Night Council of Bikugih, a vampiric race called the Sou(ou)shi offered the Venusians a way out in their vast spaceship. When the Venusians found out that the Sou(ou)shi just wanted to consume their race, the Volcano people destroyed the Sou(ou)shi ship, causing a dust cloud that prolonged Venusian civilisation for another hundred generations. The Sou(ou)shi escaped to primeval Earth where they waited for life to evolve into a sentient form that they could use.
[The Doctor approximates the date as 3 billion BC (p. 18) and 3.5 billion BC (p. 159).]
c. 3,000,000,000 BC
[Some of] the Great Old Ones visit Veltroch, and leave behind ancient carvings. There are no other records of their influence on the planet.
[White Darkness. The carvings are said to be at least 3 billion years old (p. 90)]
c. 1,000,000,000 BC
The last seas dried up on Androzani Major.
[One billion years before The Caves of Androzani]
c. 1,000,000,000 BC
The Nestene Consciousness began their conquest of other worlds.
[One billion years before Spearhead from Space.]
c. 500,000,000 BC
A spacecraft visits Earth, leaving trace elements of warp-drive radiation.
[500 million years before Invasion of the Cat-People page 3 (set 39,780 BC), it may be intended as a reference to Scaroth's ship in City of Death. On the other hand, page 2 suggests that it's only 1,000,000 years after Adric's crash in Earthshock (65 million BC)]
c. 352,000,000 BC
The descendants of Lungfish evolve into Ichthyostega, the first true amphibians.
[According to the Doctor's dream in Transit (p. 1) this happened two million years early. Current evolutionary theory tells us this was about 350 million years ago.]
h. 200,000,000 BC
At this point, all of Earth's landmasses are part of a super-continent called Pangaea.
[This is shown on a globe in The Silurians, and dated by evolutionary/geological theory (Pangaea existed 335 to 175 million years ago).]
c. 180,000,000 BC
A plesiosaurus was kidnapped and placed in a miniscope.
[We see it in Carnival of Monsters (ep. 1). The plesiosaurus lived from 199.6 to 175.6 million years ago.]
c. 152,000,000 BC
Whitaker transported an apatosaurus to the UNIT era as part of Operation Golden Age.
[Invasion of the Dinosaurs. The apatosaurus lived from 152 to 151 million years ago.]
c. 150,000,000 BC
On the planet Kastria, the scientist Eldrad created barriers to keep out the solar winds that had ravaged the planet. He also devised a silicon-based form for the Kastrians and built machines that would replenish both the planet and its atmosphere. Eldrad then attempted to seize control and go on a galactic war of conquest. The rest of the population declined to co-operate and destroyed the barriers, sending him into space in an obliteration module. The capsule was prematurely detonated at nineteen spans, due to a computer fault. Against odds of one in three million, Eldrad survived. His hand eventually reached Earth and became buried in a Jurassic stratum of Blackstone Dolomite.
[According to the Doctor, this happened 150,000,000 years before The Hand of Fear.]
c. 150,000,000 BC
Whitaker transported a pterodactyl to the UNIT era as part of Operation Golden Age.
[Invasion of the Dinosaurs. The pterodactyl lived from 150.8 to 148.5 million years ago.]
c. 140,000,000 BC
The Xeraphin's planet is devastated by the Vardon-Kosnax war, and they flee to Earth. They are poisoned by radiation sickness, and form themselves into a gestalt entity to regenerate. This process is interrupted by the intervention of two Time Lords.
[The date is given by the Doctor. He also says that it's the Jurassic era (actually 201 to 145 million years ago), and that they can't be far off the Pleistocene era (2.58 million years ago to 11,700 years ago). We've gone with the most precise of those three dates.]
c. 110,000,000 BC
Deinoychus dinosaurs leave fossilised footprints in the area that will become California.
[The Doctor recognises the species deinoychus footprints, and dates them as having gone extinct 120 million years ago in A Town Called Eternity (p. 16). These are presumably the same dinosaurs that the Master identifies as Velociraptors on the basis of Jurassic Park. The species is currently believed to have lived 115 to 108 million years ago.]
c. 85,000,000 BC
The hadrosaur existed in what would become California.
[We see a fossil of one in A Town Called Eternity (Short Trips and Side Steps) (p. 20). The Doctor claims it is 130 million years old, give or take 10 million years. The species actually lived from 86 to 66 million years ago.]
c. 70,000,000 BC
The ornithomimus is alive at this time.
[The Doctor says it comes from the Cretaceous era (145 to 66 million years ago) in Blood Heat. The ornithomimus actually lived from 76.5 to 66.5 million years ago.]
c. 67,000,000 BC
Whitaker transported a triceratops and a tyrannosaurus rex to the UNIT era as part of Operation Golden Age.
[Invasion of the Dinosaurs. Both species lived from 68 to 66 million years ago. Blood Heat shows a sign at Cheddar Gorge which says that these species lived in the Cretaceous period, 85 million years ago (p.45). Since the sign is in a parallel timeline version of the 1970s, and also mentions the brontosaurus (which was later realised to be a mislabeled apatosaurus), We're going with the historical dates.]
c. 67,000,000 BC
The Rani obtained some Tyrannosaur embryos.
[This is mentioned in Mark of the Rani. T Rexes lived from 68 to 66 million years ago.]
c. 65,000,000 BC
A spacecraft from 2526 AD exploded in Earth's atmosphere, killing most of the Dinosaurs and a great deal of other life. This was watched by the Timewyrm. It released a massive dust cloud, and lowered the temperature.
[The date is given by the Doctor. Timewyrm: Revelation (p. 113) establishes that the arrival of the moon finished the job, explaining why the Earth Reptiles had dinosaur pets in The Silurians and Blood Heat. Some details are from Transit (p. 1-2). In Face of the Enemy (p.215) the Master refers to this as the K/T impact.]