Science

New Zealand Once Had Giant Penguins and Parrots, but Why?

Two new fossil discoveries hint at the complex evolution undertaken by the island's ancient—and often huge—birds.

Nobody does giant birds like New Zealand.

Go back in time 1,000 years, and you might have cowered in the shadow of the Moa, a ratite bird that stood taller than a polar bear. Look past those behemoths into the sky, and you’d have seen soaring Haast’s Eagles, some of the largest raptors to ever exist. These flying death machines were so big, they actually hunted the 500-pound Moas.

Zip back another 19 million years, and there would have been giant, waist-high parrots. Nicknamed Squawk-zilla by researchers, this bird would have had a formidable beak and, at over three feet in height, clocks in as the largest parrot known to science, according to a new study published in Biology Letters.

Forty-some million years before that, when the planet was still reeling from the dinosaur extinction, you might have stood eye-to-eye with a massive, murderous-looking penguin that weighed nearly as much as Sidney Crosby, captain of the human ice hockey team known as the Pittsburgh Penguins.

Don't worry, though. With a long beak more like a stork’s, these monsters likely evolved to dine on fish, according to another new study published recently in Alcheringa: An Australasian Journal of Palaeontology. A time-traveling human probably would have been safe. 

So what gives? Why should one little corner of the world be so rich in gigantic avian megafauna? Is it something in the water, as they say?

“I think that there’s no single answer to that, unfortunately,” says R. Paul Scofield, co-author of both the parrot and penguin studies and a senior curator at Canterbury Museum in New Zealand.

Take Squawk-zilla. At around 15 pounds in weight, this species would have been roughly double the size of the next largest known parrot, the still-kicking Kākāpō. And the reason it got so big comes down to that old saw: location, location, location.

Fifty-two million years ago, the islands of New Zealand separated from a ginormous supercontinent known as Gondwana. And for some reason, no large, predatory mammals caught the ship as it was setting out to sea. Or those that did didn’t last long.

“What appears to have happened in New Zealand is that most of the animals that have become gigantic seem to have flown here,” Scofield says. And once there, the birds found a large, productive ecosystem mostly absent of hungry mouths that could eat them or compete with them for foliage.

Not only was there a smorgasbord of food, but the lack of predators took away the selective pressures that keep flying birds aloft. As the generations went on, many of these birds, including the Squawk-zilla and later the Moa, evolved toward flightlessness, says Scofield. At the same time, they just kept getting larger than their ancestors.

This is what scientists refer to as island gigantism, and it’s the same process that seems to have sculpted other oversized bird species, such as the Dodo, Sylviornis, and the Adzebills.

New Zealand’s hefty penguin, however, seems to have arrived at its mass by a different route.

Unlike species that require eons to achieve their gigantitude, “these penguins became very large very early in their evolution,” says Gerald Mayr, a zoologist and curator at the Senckenberg Research Institute in Germany. For these birds, opportunity was the name of the game.

As most people know, the dinosaurs went kaput approximately 66 million years ago. But what many don’t realize is that a mass extinction also occurred across the earth’s oceans, snuffing out massive marine predators like the mosasaurs and plesiosaurs. When these species disappeared, many other species flourished, says Mayr, who was lead author of the penguin paper. This is what’s known as mesopredator release.

For whatever reason, the penguins survived the event that killed off most of the large creatures on earth. Suddenly free from the threat of aquatic nightmare reptiles, the penguins multiplied and prospered, quickly evolving bigger and bigger body sizes, the better to take advantage of the bountiful vacuum left behind by that sweet, serendipitous mass extinction.

In all, scientists have found around 10 species of giant penguin that evolved in the gap, says Mayr. All of them are extinct today, alas. But that might not have been the case if it weren’t for rise of the marine mammals.

“Marine mammals became excessively large in the Eocene and the Oligocene,” Scofield says. “They pretty much outcompeted virtually every other large predator, except for the large sharks.”

At roughly 176 pounds, the colossal penguin would probably have made a tasty feast for marauding marine mammals and super-sized sharks alike. Which reminds me, whose idea was it to go back in time again? 

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