That's a very nice sentiment, but aside from the obvious (dolphins, a few whales, some primates, and elephants) do you have any sort of proof or justification for this statement? "Many many" is a very strong claim.
You just named "many", as far as I'm concerned. How many proven examples do we need before we start to think that the only reason we don't know of 1000s more is because of lack of research?
You also forget cephalopods. Oh, and Magpies and some other birds.
