Modern penguin species, ranging from Antarctica to the Galapagos Islands, are perfectly adapted to life at sea. Their torpedo body-shapes and blade-shaped wings enable them to swim at a pace of 22 miles an hour. Of the 18 penguin species on earth, only one is occasionally found north of the equator – the Galapagos Penguin (Spheniscu mediculus). Penguins are synonymous with Antarctica and the southern oceans thanks to movies like Happy Feet and Disney Nature’s Penguins. These flightless birds have called the Southern Hemisphere home for over 62 million years, and due to their perfect adaptation to the harsh conditions, have remained mainly unchanged for the same period of time. However, some ancient penguin relatives were much different from the quirky flightless birds we see today, such as the giant penguins of New Zealand.

The Giant Penguins of New Zealand

The first penguin fossils were uncovered in 1859, and since then, more than 50 species have been identified. The oldest of these were found in New Zealand, and showed that some really large penguins used to exist. Paleontologists have found fossilized penguin bones of multiple penguin species in North Canterbury, New Zealand. These ancient penguins swam in warm tropical seas that mostly submerged the land that is now New Zealand. These birds ranged from familiar sizes, like that of the yellow-eyed penguin, all the way up to 1.6 m (5.2 ft) tall giant penguins. 

Scientists discovered 9 different ancient penguin species at Waipara, North Canterbury, and the tallest penguins included species such as copeteryx, kumimanu, waimanu, muriwaimanu and sequiwaimanu. These penguins were as tall as men, and were some of the earliest penguins, living 62 million years ago. It is estimated that the largest of the ancient penguin species weighed about 220 pounds (100 kg). By comparison, the largest living penguin species, the Emperor Penguin (Aptenodytes forsteri) found in Antarctica, reaches about 4 feet in height, weighing on average 49 to 99 pounds.

These giant penguin fossils, along with life-sized models of the penguins, are available for viewing at the Canterbury Museum, New Zealand.

Credits: Canterbury Museum /Journal of Zoological Systematics and Evolutionary Research, 2020; DOI: 10.1111/jzs.12400

Northern Hemisphere Doppelgangers

New research has revealed that it was not just New Zealand that provided a home for giant marine birds. A study published in the Journal of Zoological Systematics and Evolutionary Research has determined that the renowned giant penguins of New Zealand had northern doppelgängers in Japan, the United States and Canada. The researchers identified shocking similarities between the fossilized bones of the giant New Zealand penguins and those of a much younger group of birds found at numerous sites in the Northern Hemisphere, named plotopterids. The scientists are Dr. Gerald Mayr of Senckenberg Research Institute and Natural History Museum, Frankfurt; James Goedert of the Burke Museum of Natural History and Culture and the University of Washington, USA; and Canterbury Museum Curators Dr. Paul Scofield and Dr. Vanesa De Pietri. This is an amazing discovery and might help researchers understand how birds evolved to use their wings as flippers and not for flight.

The plotopterids evolved in the Northern Hemisphere, and appeared around 37 to 34 million years ago, meaning they are much younger than the giant penguins of New Zealand. Their fossils have been found at several sites in North America (including California, Orgegon, Washington and British Columbia) and Japan. Based on the fossils, it appears that they used their flipper-like wings to swim in the ocean. However, unlike penguins, which have survived to today, the last plotopterid species became extinct around 25 million years ago, after a short 10 million year existence.

Why Doppelgängers?

Doppelgänger is defined as “a biologically unrelated look-alike”. When comparing the fossils of plotopterids with those of the giant penguin species Waimanu, Muriwaimanu and Sequiwaimanu, researchers found that plotopterids and ancient penguins had similar long beaks (possibly used to spear their prey like storks – different to the wedge-shaped beaks of living penguins) and slit-like nostrils on the beaks, similar chest and shoulder bone morphology, and similar flipper-like wings and wingspans (although these wings differed from modern penguins as they were more flexible and could probably bend a bit farther than penguin flippers can today). 

These similarities suggest that both groups of birds were strong swimmers, using their flippers to propel them through the water, possibly to search for food. Size-wise the two groups also showed similarities, with the largest known plotopterids over 2 meters (6 ft) tall, while the largest giant penguin species was 1.6 meters (5.2 ft) tall.

Credits: Canterbury Museum /Journal of Zoological Systematics and Evolutionary Research, 2020; DOI: 10.1111/jzs.12400

Despite these similarities with ancient penguins, it is clear that the plotopterids are more closely related to flying seabirds (i.e. pelecaniform birds) such as boobies, gannets and cormorants than they are to penguins. Plotopterids did however look remarkably like the ancient penguins, and we would’ve been hard-pressed to tell them apart from a distance. However, even though they looked, swam, and possibly hunted like penguins, plotopterids were not penguins. Other differences between the two groups include their appearance at different points in history, as well as their existence in different hemispheres, which further supports the theory that plotopterids shared ancestors with common northern hemisphere seabirds.

The similarities between the ancient giant penguins and the plotopterids are due to convergent evolution. Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time, due to similar environmental conditions. The parallels between the evolution of these two ancient bird groups may provide researchers with an explanation of why birds evolved to use their wings to swim, and why birds across the globe adapted to life in marine environments rather than aerial environments. Most swimming birds use their feet to swim, so wing-propelled diving and swimming is a rare trait among birds. Scientists are guessing that both penguins and plotopterids had flying ancestors that would dive into the water from the air in search of food. Over time, these ancestor species got better at swimming and worse at flying, until they became completely flightless.

The rise of marine mammals may have doomed giant penguins and plotopterids. As mammals moved into the oceans, evolving into whales, dolphins, and seals, it is possible that large marine birds were outcompeted for prey as well as safe beaches to raise their young. It is possible that modern seals pushed the giant penguins and plotopterids out of their breeding sites, allowing only smaller penguins in the south, and flying seabirds in the north, to survive.