It’s been proven that quite a few species of animals and birds have intelligence, speech, empathy, critical thinking, and analysis levels similar to those of humans. Dolphins, birds, parrots, dogs, monkeys to name a few.
What if this is true for all major eras in Earth’s history where what we define as animals/birds roamed the world? (As in, not lower celled life).
Could that mean that various eras of dinosaurs or early humans evolved intelligence levels appropriate to go beyond just their survival – problem solving, play, one-up-man-ship, etc.
But how can we figure this out? There would be some markers in the brains or bodies of current fauna to measure or perhaps only point to their intelligence. Would fossils allow us to find the same markers?
If I get a chance, I’ll google around to find out more on this topic. If you know something about this, dear reader, please let me know? In the comments or on socials would be great!
There is a chapter about that in “The Science of Discworld” (https://wiki.lspace.org/Book:The_Science_of_Discworld)
I recommend that book if you like the discworld books.
Tldr: There is a high chance this happened without leaving a detectable trace.