King Ghidorah’s Arrival to Earth

King Ghidorah (alien with unknown origins) arrives to earth 65 million years before the events of the comic.

King Ghidorah sent(or on his own terms) to Earth
Either way, his goal is to convert the biomes of Earth for something more suitable to his biology

Mass Extinction of 75% of life on Earth (K-T event)
Godzilla’s disturbance from hibernation
Volcano eruptions globally
Certain Kaiju also reawakened, varied reactions
Eventually leading up to the first King Ghidorah - Godzilla battle (before the main story)

The KT extinction. Ghidorah encased in a meteor via unknown means lands on Earth (Chicxulub Impact)
Begins to cause destruction and announces himself as King, obv certain kaiju (and not just Godzilla) aren’t too fond of that
Massive hurricanes ravage the lands, eventually Godzilla fights Ghidorah and later joined by Mothra and one of the ancestors of Rodan - they fight together to take down Ghidorah.
Ends with all three heads being blasted off, but due to alien biology (the body left undisturbed) Ghidorah survives in a weakened, dormant state...

KT extinction Ghidorah is stronger than the one featured in the main comic (not to say that he’s weak. Just KT Ghidorah survived massive, direct meteor impact into earth). After fight with Godzilla, Mothra and Rodan he was weakened greatly and spent much of his energy regenerating
Obv strong enough due to the fact he can survive all three heads decapitated