Octopodes are definitely very bright and capable of tool use, but they have three major barriers to achieving civilisation - they only live a couple of years, most species aren't social, and they are carnivorous. read more
Octopi can already survive a surpisingly long time outside water, so let’s give them 20 million years to achieve true amphibious status. Then another 100 million years to diversify into a variety of land-dwelling species. read more