There was a study funded by NASA on the topic which made the rounds back in the day. Here is the Scientific American take: [1], here is PBS Space Time YouTube:

There was a study funded by NASA on the topic which made the rounds back in the day. Here is the Scientific American take: [1], here is PBS Space Time YouTube: [2] The topic pops up now and again, most recently called the The Silurian Hypothesis. There are many articles in respectable sources on the subject, it goes beyond science fiction into literal science. For example, you might wonder how long it would take for some large portion of the surface of the earth to subduct. I believe the answer to that question is in the paper discussed in that article. 1. https://www.scientificamerican.com/article/could-an-industrial-prehuman-civilization-have-existed-on-earth-before-ours/ https://www.scientificamerican.com/article/could-an-industri... 2. https://www.youtube.com/watch?v=vyEWLhOfLgQ&ab_channel=PBSSpaceTime https://www.youtube.com/watch?v=vyEWLhOfLgQ&ab_channel=PBSSp...