Twin Tribulation: the Fall of the Moon

In order to save human civilization that was on the verge of extinction due to a helium flash in the sun, a team traveled back to the age of dinosaurs, only to discover that there was an independent "lunar" civilization on the moon. Two civilizations with the same origin but distrust each other, at the last moment of joining forces to fight against the world-destroying meteorite, fell short due to suspicion, and together they witnessed the shattering of the moon and the end of the age of dinosaurs.