Hesperornis is an extinct genus of flightless aquatic birds that lived during the Santonian to Campanian sub-epochs of the Late Cretaceous (89-65 mya). Hesperornis were very large birds, reaching up to 2 meters (6.5 feet) in length. They had virtually no wings, swimming with powerful hind legs. Their toes were probably lobed rather than being webbed, as in today's grebes; like in these, the toes could rotate well, which is necessary to decrease drag in lobed feet but not in webbed ones such as in loons, where the toes are simply folded together.

Hesperornis

Hesperornis is an extinct genus of flightless aquatic birds that lived during the Santonian to Campanian…