Fossilized remains of the largest penguin known to science were recently discovered in New Zealand, shocking researchers who determined the massive bird weighed hundreds of pounds.
Named Kumimanu fordycei, paleontologists believe the species could have weighed up to 340 pounds. By comparison, the average adult male Western lowland gorilla weighs about 300 pounds.
The fossil was discovered in a 57-million-year-old boulder that had been cracked open with the tides. Along with it they also found the remains of several individual specimens of another large but not quite as big previously undiscovered ancient penguin named Petradyptes stonehousei and fragments of two smaller yet-unnamed species of ancient penguins.
Scientists estimate the newly-discovered penguins lived around 60 million years ago. Petradyptes, they estimate, weighed around 110 pounds, far smaller than the Kumimanu, but still large for a penguin. The emperor penguin, the largest penguin on Earth today, can weigh up to just 88 pounds.
The fossils were discovered by Alan Tennyson, a paleontologist at the Museum of New Zealand Te Papa Tongarewa in 2017, but were described and named on Wednesday in the Journal of Paleontology.
Most of what scientists know about the Kumimanu fordycei came from a humerus bone, which was nine and a half inches long - about twice the length of those in the emperor penguin.
Paleontologists have been unable to determine the height of the ancient giant penguin but one estimated that it probably stood about 5 feet 2 inches. That gives the giant penguin a stocky build - the average aforementioned Western lowland gorilla stands at about 6 feet while being roughly 40 pounds lighter.
Coming from an older branch of the tree of the penguin evolutionary tree, both the Kumimanu and Petradyptes differed in appearance from modern day penguins in more ways than just their size. Paleontologists say they had primitive flippers that resembled flying and diving birds like puffins. Their leg structure was also angled forward, unlike modern penguins whose legs are shaped like an upside down “L” coming out of their spine.
New Zealand has been a hot spot for finding ancient penguin fossils. In 2017, a closely related Kumimanu biceae was described as living just a few million years after the fordycei and weighed 220 pounds. The slightly slimmer giant penguin had a sharp “stork-like” beak that researchers think may have been used to stab prey. The beak of the Kuminmanu fordycei has not yet been discovered.
In 2021, a 4.5-feet tall penguin with unusually long legs was described after a group of students in a fossil hunting club found fossilized remains on a small peninsula in the Kawhia Harbor during a field trip.
One explanation for why giant penguins thrived at the time is because they evolved shortly after the meteor that killed off the dinosaurs hit Earth. That impact also killed most of the sea-faring reptiles, leaving a niche open for a large amphibious predator to fill their space. Sea-faring mammals, like seals and whales, had not yet evolved. Paleontologists hypothesize that once mammals reentered the sea, the giant penguins were out-competed and only the smaller penguins survived.
It is also worth noting that scientists now believe New Zealand and the island of New Caledonia are a part of the Earth’s eighth continent, with most of the landmass sitting below the sea. This continent is known as Zealandia, which they believe broke off from the Southern Hemisphere supercontinent of Gondwana about 105 million years ago.
What would become Zealandia then stretched out in a process scientists don’t yet understand. Scientists are still debating if most Zealandia was always submerged, with just small islands poking out, or if it sank at one point. In either case, a sinking continent or a collection of islands make for a natural habitat for penguins. If it did sink, scientists estimate that it would have taken over a hundred million years, meaning the giant penguins could have lived while much of Zealandia was still above sea level.