Giant Penguin

Fossil evidence of a giant penguin were found recently. Inkayacu paracasensis or Water King, had brown and grey plumage instead of the modern white and black. Along with the Icadyptes salasi another species discovered a few years ago, these birds lived in what is now Peru about 36 million years ago. They stood over five feet tall and were twice as heavy as today's largest penguin, the Emperor which stands at 3ft 7in and weighs 75 lbs. They may also have been able to dive to great depths judging by their large size. The Emperor often dives to 200m (and the record is 565m)
Articles describing these penguins are from the BBC and can be found here and here.

And strangely the mention of giant penguins makes me think immediately of HP Lovecraft.
An odd association to be sure, but there is a mention of penguins in his 1931 story At The Mountains of Madness.

This white, waddling thing was fully six feet high....a penguin—albeit of a huge, unknown species larger than the greatest of the known king penguins, and monstrous in its combined albinism and virtual eyelessness.

The story has little to do with penguins at all, for some reason their brief presence within the story has stuck with me. They have little significance to the plot but perhaps it is there recognizable familiarity within this strange Lovecraftian mythology that grounds the story. It is actually a tale of an Antarctic Expedition and the discovery of a race of Ancient beings. Genuinely creepy and written with excellent detail I find it to be one of his better stories.

The complete text can be found here.

The image below is from the Spanish Graphic Novel En Las Montañas de la Locura illustrated by Enrique Breccia