Sphenisciformes

Penguins are a group of flightless semi-aquatic sea birds which live almost exclusively in the Southern Hemisphere. Only one species, the Galapagos penguin, lives at, and slightly north of, the equator. Highly adapted for life in the ocean water, penguins have countershaded dark and white plumage and flippers for swimming. Most penguins feed on krill, fish, squid and other forms of sea life which they catch with their bills and swallow whole while swimming. A penguin has a spiny tongue and powerful jaws to grip slippery prey.

Icadyptes is an extinct genus of giant penguins from the Late Eocene tropics of South America.

Waimanu is a genus of early penguin which lived during the Paleocene, soon after the Cretaceous–Paleogene extinction event, around 62–60 million years ago. It was about the size of an emperor penguin (1 metre (3.3 ft)). It is one of the most important bird fossils for understanding the origin and evolution of birds because of the time period it comes from, and the position of penguins near the base of the bird family tree. alt=Artist's reconstruction of fossil penguin Waimanu manneringi|thumb|Artist's reconstruction Waimanu was a very early member of the Sphenisciformes, the order that include

Inkayacu is a genus of extinct penguins. It lived in what is now Peru during the Late Eocene, around 36 million years ago. The only species, I. paracasensis, was named from a single nearly complete skeleton discovered in 2008. It includes fossilized feathers, the first known in penguins. A study of the melanosomes, pigment-containing organelles within the feathers, indicated that they were gray or reddish brown. This differs from modern penguins, which get their dark black-brown feathers from unique melanosomes that are large and ellipsoidal.