Now let's say someone from our present-day visits a prehistoric Earth and returns.

It is a world similar to prehistoric Earth but has three moons.

To pinpoint the exact location of a cave on prehistoric Earth.

They stood there alone on a hill on prehistoric Earth and stared each other resolutely in the face.

Arthur could hardly bear the fact that it was the same sofa which had appeared to him in the fields of prehistoric Earth.

It was a survival crisis comparable to the ice ages of prehistoric Earth.

"Though my father says they are smaller than those you built on the prehistoric Earth."

Bornstellar's curiosity leads him to prehistoric Earth where he meets the humans.

This would result in the Ark venturing out and then crashing into prehistoric Earth.

Again the spocy images of prehistoric Earth rumbled by like a grade school simulation.