Penguin

Aptenodytes

Evolution

Penguins are actually very old birds. The oldest fossils of penguins emerged in the Eocene era more than 40 million years ago. However these fossils proved that prehistoric penguins were already flightless and seagoing, so their origins may go as far back as 65 million years ago. Had the dinosaurs not died out, penguins could look like this http://www.bowdoin.edu/~dbensen/Spec/Sphenisciformes.html. With no more giant marine reptiles and prehistoric marine birds like Hesperornis, penguins diversified. During the Eocene, penguins had no competition as top aquatic predators. Some extinct penguins grew larger than humans. Birds like Palaeeudyptes from the Eocene, Pachydyptes from the Miocene and the now extinct Great Auks resembled modern penguins. The links between other bird orders and penguins are still unknown, and though a close relationship between penguins, Procellariiformes and Gaviiformes is usually assumed, it has not been proved and some anatomical evidence has been interpreted as supporting a placement of Spheniscidae within a group of birds classified as Pelecaniformes. Most fossil penguins known are large, but not larger than the modern Emperor Penguin. This size is maintained because at the time, there were no marine mammals so far south. By the Miocene and Pliocene, marine mammals colonized the southern hemisphere, wiping out a vast majority of the penguins at the time. Only 17 species survived, dwarfs compared to the fallen giants so long ago. All lived in the southern hemisphere.

Related Topics:
Eocene - Marine reptiles - Hesperornis - Miocene - Great Auk - Procellariiformes - Gaviiformes - Pliocene - Southern hemisphere

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