Hesperornis closeup
Hesperornis is a flightless sea bird from the cretaceous period.  They are good divers, they can dive into the water from the surface up to maybe a mile with one breath of air similar to the penguin.  They have clumbsy legs which does not help it very well while walking so they may have waddled like Penguins.  There prefered food is mainly fish, they can be taregeted by sharks and other marine reptiles.  They lived around the western interior sea.