[aziaziazi]

> The largest birds are smaller than the largest mammals on land or at sea

With all my respect to you theory I think comparing size of animals should not ignore the medium they moved in: water, land or air. Weight is (loosely but still) related to size. It’s probably not a coincidence the largest mammals lives on water where they need less energy to supper their weight, and it’s not a coïncidents the largest mammals on earth are way bigger that bats.

The biggest bats are ~1.7m which is not so far from biggest albatros (3.7m).

Also consider the biggest bird (Ostriches) can’t fly. Now I’m trying to picture a swimming gigantic bird.

[vanderZwan]

Well, fair. But birds are warmblooded too so that doesn't change much there, and on top of that the difference in requiring bigger lungs for the same amount of oxygen extraction would exactly add much weight per volume, so to speak

[totallykvothe]

An Emperor Penguin?

[aziaziazi]

Right! To complete the unusual list : flying fish and... Amphibious fish! Wikipedia says there's 11 of them. Ok stop procrastinating now.