Dolphins use one hemisphere of the brain, while second is sleeping, but potentialy, but imagine the situation, they mutate to have leglike things, while no in water, they don't need to put one hemisphere to sleep...

Dolphins intellegence roughtly compares to chimpanzee, which by itself equates to 80-90 and thats only using half of the brain, imagine them using both parts of their brains.

This really creeps me out