[zw123456]

They used to be land mammals. Maybe they had a civilization, but they ruined the climate with it, then evolved to be sea mammals but kept their intelligence? https://en.wikipedia.org/wiki/Silurian_hypothesis

[alchemist1e9]

Yes! another fan of the Silurian hypothesis. I know most dismiss it but there really are oddities in the geological record that are somewhat consistent with it.

[MattPalmer1086]

Do you have any references to these oddities? Always fun to think about things like this, but can't find much about it.

[zw123456]

Agree. No proof, I know, but such an interesting idea to think about!