A skeleton of the late Cenozoic “pseudotooth bird”, Pelagornis. As the name would imply, what you see in its mouth aren’t true teeth, but protrustions of its beak. Pelagornis itself could attain a wingspan in excess of 15 feet (approx. 3 meters), but even “small” pelagornithids were particularly big for flying birds. These birds went extinct in the Pleistocene, but for much of the Cenozoic they might well have taken up the ecological niche left empty by some pterosaur groups at their extinction 66 million years ago.