[Red Badger]

So, did they survive?

What was Earth like 3 million years hence?...............

[Mr170IQ]

Yes, they survive and return to a very changed Earth. There are still people living there, although not many.

You can read the plot summary in eight paragraphs at
https://en.wikipedia.org/wiki/A_World_Out_of_Time

and you can download the entire novel online as a pdf at https://silo.pub/qdownload/larry-niven-a-world-out-of-time-o-5405644.html

If you decide you want to read other stories based in this alternate future timeline , I would recommend his books “The Integral Trees” and “The Smoke Ring”

Forty years ago I was a major Larry Niven fan, but lately I’ve found weaknesses in his writing style.