Penguins

The basal penguins lived around the time of the Cretaceous–Tertiary extinction event somewhere in the general area of (southern) New Zealand and Byrd Land, Antarctica. Due to plate tectonics, these areas were at that time less than 1,500 kilometres (930 mi) apart rather than the 4,000 kilometres (2,500 mi) of today. The most recent common ancestor of penguins and their sister clade can be roughly dated to the Campanian–Maastrichtian boundary, around 70–68 mya. What can be said as certainly as possible in the absence of direct (i.e., fossil) evidence is that by the end of the Cretaceous, the penguin lineage must have been evolutionarily well distinct, though much less so morphologically; it is fairly likely that they were not yet entirely flightless at that time, as flightless birds have generally low resilience to the breakdown of trophic webs that follows the initial phase of mass extinctions because of their below-average dispersal capabilities (Flightless Cormorant).
• The basal fossils
The oldest known fossil penguin species is Waimanu manneringi, which lived in the early Paleocene epoch of New Zealand, or about 62 mya. While they were not as well-adapted to aquatic life as modern penguins, Waimanu were generally loon-like birds but already flightless, with short wings adapted for deep diving. They swam on the surface using mainly their feet, but the wings were – as opposed to most other diving birds, living and extinct – already adapting to underwater locomotion.
Perudyptes from northern Peru was dated to 42 mya. An unnamed fossil from Argentina proves that by the Bartonian (Middle Eocene), some 39–38 mya, primitive penguins had spread to South America and were in the process of expanding into Atlantic waters.