Dolphins are pretty smart, I have always thought that they are merely limited in their evolutionary progression by the fact that it is difficult to generate and

Dolphins are pretty smart, I have always thought that they are merely limited in their evolutionary progression by the fact that it is difficult to generate and control fire underwater (and therefore difficult to cook food, smelt metal etc.), and also difficult to domesticate oceanic creatures for agri(aqua?)culture. See also; octopodes.