Penguins today are not that big. Even big penguins aren’t that big — about four feet tall, at best. But that wasn’t the case tens of millions of years ago, says a team of scientists who recently dug up some terrifying bird remains in New Zealand.

Their find, which they describe in a Nature Communications paper published Tuesday, indicates that in the early Cenozoic Era, shortly after the Cretaceous–Tertiary extinction that killed off the dinosaurs, the ocean around New Zealand was home to a penguin far larger than any that exists today.

The penguin species is dubbed Kumimanu biceae, which means “monster bird” in the Maori language. This extinct bird deserved its name, seeing as it measured over five and a half feet from beak to tail and tipped the scales at over 200 pounds. This fossil specimen, as big as an adult human, is one of the largest ever identified.

Kumimanu biceae
The Kumimanu biceae penguin weighed over 200 pounds. Needless to say, it could probably fuck you up.

A team of paleontologists, led by Gerald Mayr, Ph.D., a curator at the Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany, used stratigraphy — the process of comparing a new specimen to familiar fossils nearby to guess its age — to conclude that this giant penguin is between 60 and 55 million years old.

The study’s authors write that this fossil reveals some crucial information about penguins’ evolutionary history. Most significantly, it indicates that penguins got really big right around the same time they started living as swimming birds who don’t fly.

“That a penguin rivaling the largest previously known species existed in the Paleocene suggests that gigantism in penguins arose shortly after these birds became flightless divers,” they write.

bone comparison
A humerus (top) and a shoulder bone (bottom) from the newly discovered penguin, compared to those of another large extinct penguin (center) and an emperor penguin (right).

At this point in the world’s history, millions of years before whales had entered the ocean, giant penguins basically had the run of the place. But its reign was short-lived; as larger, more aggressive animals began to fill the ocean and compete for food, populations of these ‘monster birds’ likely evolved into the penguin species — which, to its credit, is still quite fierce — we know today.

Abstract: One of the notable features of penguin evolution is the occurrence of very large species in the early Cenozoic, whose body size greatly exceeded that of the largest extant penguins. Here we describe a new giant species from the late Paleocene of New Zealand that documents the very early evolution of large body size in penguins. *Kumimanu biceae, n. gen. et sp. is larger than all other fossil penguins that have substantial skeletal portions preserved. Several plesiomorphic features place the new species outside a clade including all post-Paleocene giant penguins. It is phylogenetically separated from giant Eocene and Oligocene penguin species by various smaller taxa, which indicates multiple origins of giant size in penguin evolution. That a penguin rivaling the largest previously known species existed in the Paleocene suggests that gigantism in penguins arose shortly after these birds became flightless divers. Our study therefore strengthens previous suggestions that the absence of very large penguins today is likely due to the Oligo-Miocene radiation of marine mammals.

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