Scientists have found a new extinct species of penguin that was as big as a man.

The creature that lived millions of years ago in New Zealand would have been almost 5 feet 10 inches in height and weighed about 220 pounds, according to the researchers’ estimates in the journal Nature Communications. They called it “an exceptionally large bird.”

The researchers named the new penguin species Kumimanu biceae — the genus includes the Maori words for “large mythological monster” and “bird.” Its bones date to between roughly 55 million and 60 million years ago.

Scientists have previously found bones from other extinct species of giant penguins, and there has been some debate about how they became so huge.

In addition to being one of the largest ever discovered, “the new fossil is one of the oldest giant penguins found so far,” the study says, adding that it also belonged to a creature that was not closely related to the other giants.

That suggests the massive size evolved separately.

It could have been connected to the mass extinction event that killed off the dinosaurs 66 million years ago. The giant penguins appeared shortly after that, when the Cretaceous geological period ended and the Paleogene began. According to the study, the penguins could have been filling “ecological niches left vacant after the extinction of large predatory marine reptiles.” The penguins would no longer have had to compete with the large reptiles for food, and there are benefits to growing larger, such as in mating and edging out other species in a territory. “A correlation with improved diving capabilities has likewise been discussed.”

The scientists added that understanding the role of size in penguins might be better answered by looking at why they are so much smaller today. Emperor penguins are the biggest current species, and they are only about 4 feet tall.

Researcher Gerald Mayr told the AP that the giant penguins may have died out when they started facing competition and predation from whales and seals.