Consider the humble penguin. Now consider a humble penguin that stands five feet tall. The Waimanu, the oldest penguin known to science, was just such a giant. The giant penguins, first discovered in 1980, lived in New Zealand during the Early Paleocene period. Like modern penguins, birds in the Waimanu genus were flightless and used their wings for diving. They probably looked a bit like giant, flightless loons, which evolved from the same genetic stock as penguins. Scientists recently found a Waimanu fossil that is poised to rewrite the history of bird evolution.
The fossil was found in the Canterbury region of New Zealand. The fossil has been dated to 61 million years ago. It's the one of the largest penguin fossils we've ever discovered.
The Waipara River, where the fossil was found, brags a high density of bird fossils, including the stately Waimanu. But this particular Waimanu is interesting because it is significantly different than fossils of other Waimanu species that were contemporary with it, leading researchers to conclude that penguins were much more genetically diverse early in their evolution than previously believed.
"Among the finds from these sites, the skeletons of Waimanu, the oldest known penguin to date, are of particular importance," says Dr. Gerald Mayr, an ornithologist from the Senckenberg Research Institute in Frankfurt.
The research team that found the fossil published a study in the Springer Journal Science of Nature that suggests the fossil indicates that birds started evolving much earlier than was formerly believed. They may have even began to appear while dinosaurs still walked the Earth.
According to Dr. Mayr, "What sets this fossil apart are the obvious differences compared to the previously known penguin remains from this period of geological history. The leg bones we examined show that during its lifetime, the newly described penguin was significantly larger than its already described relatives. Moreover, it belongs to a species that is more closely related to penguins from later time periods."
The new penguin species, though large, was still not as big as the largest penguin fossil ever found, the Anthropornis nordenskjoeld. A.nordenskjoeld lived in coastal Antarcitca between 45 and 33 million years ago, and could grow about six and a half feet long.
While A.nordenskjoeld was larger, Waimanu penguins were older. "This shows that penguins reached an enormous size quite early in their evolutionary history, around 60 million years ago," says Dr. Mayr.
Like modern penguins, the newly discovered Waimanu species probably walked with a waddle. The signature gait differentiates it from other Waimanus that probably had more elegant locomotion.
Says Mayr, "The discoveries show that penguin diversity in the early Paleocene was clearly higher than we previously assumed. In turn, this diversity indicates that the first representatives of penguins already arose during the age of dinosaurs, more than 65 million years ago.
It's oddly endearing to imagine dinosaurs rubbing shoulders with giant penguins. Too bad giant penguins can't rub shoulders with us, too.