June 25, 2007 — Human-sized, muscular penguins with enormous beaks thrived in sunny Peru 36 million years ago, according to a paper published today in the
Proceedings of the National Academy of Sciences.
Standing at 5 feet tall, Icadyptes salasi was preceded in Peru by yet another newly identified penguin species, Perudyptes devriesi, which lived there 42 million years ago and was about the same size (3 feet tall) as modern king penguins.
Since both were among the world's earliest known penguins, they represent an evolutionary stage somewhere between flying, winged birds and the waddling, flippered penguins of today.
Lead author Julia Clarke told Discovery News that the ancient Peruvian penguins had "less rigid, paddle-like flippers than living penguins."
Clarke, an assistant professor of marine, earth and atmospheric sciences at North Carolina State University, added that both prehistoric species also had "distinctly straighter and narrower pointed beaks, with that of Icadyptes being nearly twice the length of the beak of any living penguin."
This particularly long-beaked penguin also possessed "a massive arm bone," suggesting Icadyptes was one tall, buff bird.
Deep muscle scars on the back of the prehistoric penguins' skulls further indicate they had extremely powerful jaws that could snap shut to catch and squash prey, which probably consisted of big fish.
"From these new finds, we now believe that a narrow, pointed, spear-like bill may be ancestral to the penguin lineage, and the very different beak shapes seen in some living penguins that feed on small invertebrate animals evolved much later," Clarke explained.
The new fossils call into question a popularly held theory about the timing and pattern of penguin evolution and expansion. The widespread belief has been that cold-adapted penguins evolved around the South Pole and then headed north towards equatorial regions around 10 million years ago, long after a period of cooling that began 34 million years ago.
Now the new fossil evidence suggests penguins evolved in Antarctica and New Zealand before heading northward more than 40 million years ago during one of Earth's warmest periods.
