Penguins – the small, slightly clumsy birds we know and love today – had a massive ancestor. That’s according to a team of scientists that unearthed a penguin fossil and says it belonged to a roughly 350-pound bird – heavier than a typical NFL lineman.
“The emperor penguin is the largest penguin alive today,” said Daniel Ksepka, a curator at the Bruce Museum in Greenwich. “We’re talking much, much larger.”
Ksepka is the lead author of a paper outlining the fossil find, which dates to around 57 million years ago and was found in 2017 on a beach in New Zealand.
Writing in the Journal of Paleontology, Ksepka said the bird’s massive size may have given it a competitive edge – allowing it to beat out rivals for food and territory and maintain its body heat underwater.
“Being larger is a big plus if you’re a diving bird,” Ksepka said. “You can stay in the water longer without burning as much energy, and you can also, usually, dive deeper.”
Richard Prum, an ornithologist at Yale University who was not involved with the study, said scientists are learning more and more that early penguins were huge.
“The discovery of penguins that are startlingly large – you might even say frighteningly large if you were to encounter one – is always a fascinating event,” Prum said.
Ksepka’s team said measurements of the fossilized species, which they named Kumimanu fordycei, indicate it is the heaviest penguin known to science.
“We have a few other large-bodied fossil penguins – bigger than current penguins – that were already known,” Prum said. “This adds to that picture, but the fact that it also adds a new size extreme is really fascinating.”
Unearthing a ‘monster bird’
Ksepka said the fossil of Kumimanu fordycei was uncovered during a walk on the beach by study co-author Alan J.D. Tennyson.
“He found a boulder with these bone fragments,” Ksepka said. “A lot of times you only see a little piece of bone – so you might not know how much of the skeleton is there.”
But once the rock was broken away from the fossil, Ksepka said, it turned out a lot was there.
“I saw it in a drawer after it was prepped,” Ksepka said. “I was blown away by the sheer size of it.”
Since it’s impossible to measure an animal that’s long vanished from the planet, Ksepka said his team compared measurements of the fossil bone against bone measurements in hundreds of modern-day penguins whose weights are well documented. Using that data, they estimated how much the fossilized penguin would have weighed, based on the size of its bones.
“This is widely done with extinct animals like dinosaurs,” Ksepka said. “You can’t find them and weigh them on the scale, so that’s the best we can do for something that’s extinct.”
Results yielded a penguin that was astonishingly heavy – about 350 pounds. Ksepka said determining the bird’s height was difficult because they didn’t have a complete set of bones.
That big weight is reflected in the bird’s name: Kumimanu fordycei.
“Kumimanu” is an existing genus, which Ksepka said means “monster bird.” The second part of the name is to honor Dr. R. Ewan Fordyce, who Ksepka said was instrumental in building New Zealand’s paleontology program. “I can’t overstate the impact he’s made both on the field of paleontology and on people.”
Why don’t we have giant penguins today?
Scientists believe penguins evolved to massive sizes millions of years ago before perfecting their flippers. Ksepka said their big size may have helped penguins disperse in the ocean from New Zealand to other parts of the globe.
But today’s penguins aren’t behemoths. So why did the really big ones all go extinct?
“I’ve always wondered about that,” Ksepka said. “This is the biggest we’ve seen yet – but there’s other very large penguins that persist up to about 20 million years ago. So they’re there for tens of millions of years.”
“The going hypothesis is that they lost out in some way to marine mammals,” Ksepka said. “When penguins evolved, there’s no whales, there’s no sea lions – there’s no seals.”
As those animals appeared, some would actually eat penguins, Ksepka said, or begin to hog crucial beach real estate where big penguins would want to nest.
“Whereas a smaller penguin could scrabble up the rocks and take the more marginal environments,” Ksepka said.
Prum, with Yale, said many penguin researchers think whales and other large ocean-going species like dolphins outcompeted penguins, in part, by being able to give birth at sea.
“As a result, penguins today are limited to the southern oceans and a few outlying non-cold places,” he said.
“But in [these] early days, they were ocean-going. They were way out in the seas,” Prum said. “And that’s an interesting thing.”
