Apparently the period after the disappearance of the marine dinosaurs and before the emergence of the whales, sea lions, and seals was an age of giant penguins, at least in areas like New Zealand, Antarctica, and Peru.
The idea of human-sized penguins is all the more amusing, because horror writer H. P. Lovecraft, in his 1936 story AT THE MOUNTAINS OF MADNESS,* had his intrepid Miskatonic explorers
encounter giant penguins in the shoggoth-haunted tunnels beneath the Elder Things' cyclopean city.Who knew that this bit of implausible exotica wd turn out to have a real-world analogue after all?
current reading: THE LIST OF 7 (resumed; dreadful stuff)
*the worst but most popular of his novels
I did a little more checking, and it seems that the giant Peruvian penguins (a phrase I really enjoyed writing) were discovered in 2007. But their giant Antarctic cousins seems to have been known to science since about 1905. So HPL may have been extrapolating from the known instead of wildly veering off into the unknown, on this point.