Plotopteridae they became extinct. That they became extinct at the same time as the giant penguins of the Southern Hemisphere, which also coincided with the radiation of the seals and dolphins, has led to speculation that the expansion of marine mammals was responsible for the extinction of the Plotopteridae, though this has not been formally tested. Plotopteridae Plotopteridae is the name of an extinct family of flightless seabirds from the order Suliformes. Related to the gannets and boobies, they exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant penguins. That they lived in the North Pacific, the
Flightless cormorant and other small creatures. They feed near the sea floor and no more than 200 metres offshore. The flightless cormorant is the largest extant member of its family, in length and weighing , and its wings are about one-third the size that would be required for a bird of its proportions to fly. The keel on the breastbone, where birds attach the large muscles needed for flight, is also greatly reduced. The flightless cormorants look slightly like a duck, except for their short, stubby wings. The upperparts are blackish and the underparts are brown. The long beak is hooked at