Hesperornis was a toothed bird found in the late Cretaceous, 80-65 million years ago. It was 2 metres long and could not fly and could not walk properly. It spent most of its time eating (and being eaten) at sea, where it preyed on fish, ammonites and belemnites. It was popular food with most predators in the Cretaceous seas. Its brain was tiny even by bird standards. they would usualy spend most of the day on the beach, playing with each other . [1] <--- a hesperonis skeleton.