An artist's recreation of the massive penguin that lived in New Zealand 30 million years ago (Credit: Canterbury Museum)

When Leigh Love stumbled upon a bird's leg bone at the Waipara Greensand fossil site in New Zealand's South Island in 2018, he suspected that they might be those of an ancient penguin. With four other species discovered there, the area has been a hotbed for penguin remains from the Paleocene Epoch, which spanned between 66 million and 55 million years ago. What the amateur paleontologist did not realize was that the fossil belonged to the largest, hitherto unknown, penguin species ever found.

Based on the fossil's length, the research team from Canterbury Museum in Christchurch and Senckenberg Natural History Museum in Frankfurt, Germany estimated that the Crossvallia waiparensis, or "monster penguin," stood about 5.2 feet (1.6 meters) tall and weighed as much as 176 pounds (80 kilograms). In comparison, the emperor penguin, considered a giant among its peers today, is "merely" about 4.3 feet (1.3 meters) tall and weighs about 50 pounds (22.7 kilos). The giant penguins evolved after the Cretaceous period, which ended with the extinction of both dinosaurs and other giant marine reptiles, and probably benefited from the lack of predators. The scientists suspect they thrived unchallenged, until large sea-dwelling mammals, like toothed whales and pinnipeds, arrived almost 30 million years later and drove them to extinction.

The leg fossil of the giant penguin (bottom) compared to a similar bone from an emperor penguin (Credit: Canterbury Museum)

Besides its larger size, the ancient avian bone is also different in structure from those of modern penguins. The researchers believe this could be because the ancient penguins spent more time in the water than their modern counterparts. It could also be that the birds had not yet adapted to standing upright and waddling around like our penguins do today. “The fossils discovered there have made our understanding of penguin evolution a whole lot clearer,” says Gerald Mayr, a co-author of the study, published in the journal Alcheringa: An Australasian Journal of Palaeontology, on August 12, 2019. The curator at the Senckenberg Natural History Museum continues, “There’s more to come, too – more fossils which we think represent new species are still awaiting description.”

An artist's rendition of "Squakzilla," the largest known parrot, with small modern-day New Zealand wren for scale. ( Credit: Dr. Brian Choo/Flinders University)

The "monster penguins" were not the only gigantic ancient creatures to have roamed New Zealand. The island was once also home to the moa, a flightless bird that reached about 7 feet (2 meters) tall, and the massive Haast's eagle, which weighed 39 pounds (17.8 kilos) and boasted a 9.8-foot (3-meter) wingspan. In August 2019, researchers revealed that "Squawkzilla," the world's largest known parrot, which weighed 15 pounds (6.8 kilos) and stood as tall as a 4-year-old child, once soared freely in the New Zealand skies. Unfortunately, all the magnificent creatures have disappeared since humans began settling on the once-isolated island about 700 years ago.

Resources: Smithsonianmag.com, nzbirdsonline.org.nz, theguardian.com