(CNN) Today's adorable penguins waddle across kids' cartoons as comic relief. The cute cold-weather bird is a pitchman for everything from vodka to hockey. But in ancient times, you wouldn't want meet one in person.

The Paleocene penguin was no cute Chilly Willy, according to skeletal remains discovered in New Zealand and discussed Tuesday in the journal Nature Communications

The bird could look you right in the eye, being about as tall as an adult human: 1.77 meters, about 5'10". It could box as a heavyweight at 101 kilograms, or about 223 pounds. That makes the bird nearly the same weight as actor Vin Diesel or about 13 pounds shy of President Donald Trump at his last checkup. In contrast, the largest of the modern penguins, the emperor penguin , weighs up to 88 pounds and is a little over 4 feet tall, on average.

The fossilized partial skeleton is estimated to be between 59.5 milion and 55 million years old, making it one of the oldest-known giant penguins, and it's changing what we know about the early version of the bird.

The bird is named Kumimanu biceae, from kumi , which in the Maori language means a large and fabulous mythological monster, and manu , which is Maori for bird. The specific name, biceae, honors Beatrice "Bice" A. Tennyson, the mother of study co-author Alan J.D. Tennyson , vertebrate curator at the Te Papa Museum in New Zealand, who fostered his interest in natural history.

Penguin remains that were nearly 60 million years old were found in New Zealand.

The remains were identified by a team of prominent paleontologists including Gerald Mayr , an ancient-bird expert who also identified what is thought to be the oldest fossils of modern-type hummingbirds in Europe in 2004

"That was an extremely interesting find too, but the international popular press didn't make much note of it. Apparently, only penguins get major media attention," joked Mayr, curator of ornithology at Germany's Senckenberg Research Institute.

Though Mayr found those rare hummingbird bones in a museum drawer in Stuttgart, the partial primitive penguin skeleton was found in the Paleocene Moeraki Formation at Hampden Beach in New Zealand, according to the study, where paleontologists have found other ancient bird and animal remains.

The study's authors have also been able to piece together that, unlike the penguin of today, the ancient bird's beak was longer, Mayr said. Based on other finds of feather remains in Peru , scientists believe that its feathers would probably have been brown, rather than black and white.

Although penguins live in cold climates today, these ancient animals would have lived in a subtropical climate. And it's believed that gigantism in penguins may have come earlier than previously thought, possibly shortly after the birds became flightless divers, according to the study. That would be after the extinction of large predatory marine reptiles, which may have made room for these birds and other giants like the aptly nicknamed "terror birds" of South America.

Professor R. Ewan Fordyce of the University of Otago geology department in New Zealand, an expert on ancient penguins, said the discovery is "really significant and shows an interesting history about the penguin."

"They were extremely impressive animals," said Fordyce, who was not involved in the new research.

Scientists aren't sure exactly why we don't see human-size penguins now, but there are some theories. Their disappearance coincides with the rise of marine mammals such as seals or sea lions, who probably competed for food, earlier research suggests. Possibly, predators such as toothy whales hunted them to extinction.

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"The exciting thing about this find is that it suggests these penguins were living not long after the extinction of the dinosaur, and it should tell us more about the animal's overall evolutionary history," Fordyce said. "Now, they look like funny little gentlemen in tuxedos, but in this case, they were big gentlemen.

"In short, penguins have always been cool."