During the last few years, we have worked on the systematics and paleobiology of the South American and Antarctic fossil penguins. As a result, we have obtained new data about their past biodiversity. Concerning South American fossil penguins, particularly the Tertiary ones, we can point out that, based on phylogenetic and morphometric analyses practiced on skulls and appendicular skeleton, we recognised three non taxonomic groups, partially in agreement partially with the systematic scheme proposed by Simpson: Paraptenodytinae, Palaeospheniscinae and Spheniscinae. These species are recorded exclusively from South America and morphologically have more resemblance with the living species than the fossil penguins from others regions of the Southern Hemisphere. This suggests that the evolutionary and biogeographical history of the penguin fauna of Argentina, Chile and Peru followed different routes from those of Antarctica, New Zealand and Australia.