It is generally
agreed amongst biologists and archeologists that penguins evolved, somewhere
in the Southern hemisphere, from a flying ancestor around 140,000,000 to
65,000,000 years ago. The common ancestor is assumed to have been
somewhat similar to a modern-day diving petrel, or auk in appearance and
behaviour. In the 1930's it was mooted that the evolution of penguins
occured before the development of flight in birds; however, this suggestion
is largely discounted these days.
The fossil evidence is rather sparse and no intermediate species between a flying ancestor and the flightless pengiuns has ever been discovered. accordingly many authors take the view that speciation was very rapid as the penguins developed with many distinct species appearing in a relatively short period around 50 to 100 million years ago.
The closest flying relatives of the penguins today are the Procellaridae (the Albatross and Petrels) and the Gaviidae (the Divers).
The diagram indicates, very crudely, the relationships between the penguins.
