The mancallines were a lineage of flightless semi-aquatic birds closely related to auks. Known from the Pacific coasts of what are now California and Mexico, between about 7.5 and 0.5 million years ago, they convergently evolved a close resemblance and similar lifestyle to both the recently-extinct North Atlantic great auk and the southern penguins.
Miomancalla howardi here lived in offshore waters around southern California during the late Miocene (~7-5 million years ago). The largest of the mancallines, it just slightly beat out the great auk in size – standing around 90cm tall (~3′) and weighing an estimated 5kg (11lbs).
Like great auks and penguins it would have been a specialized wing-propelled diver, swimming using “underwater flight” to feed on small bait fish. It probably spent much of its life out at sea, probably only returning to land to molt and breed.