Scientists have identified a fossilized skull belonging to a giant penguin ancestor species that once lived in what is now Aotearoa, New Zealand. The rare discovery, made along the Taranaki coast, sheds new light on how ancient penguins adapted to warmer climates and raises questions about their eventual extinction.
The skull, which researchers say is 31% longer than that of today’s emperor penguins, belonged to a relative that likely stood even taller and weighed more. Its beak was longer and more robust, resembling the features of a king penguin but on a much larger scale.
Research team, which included Dan Ksepka of The Bruce Museum, noted that the penguin ancestor species thrived around three million years ago when global temperatures were approximately 3 degrees Celsius (37.4 degrees Fahrenheit) higher than pre-industrial levels.
At that time, South Taranaki sat near 40.5° south, and coastal waters reached 20°C (68°F) — far warmer than those inhabited by modern emperor and king penguins, which forage in seas closer to freezing.
Ancient penguins in warm waters
Despite the stark difference in climate, the ancient species managed to survive in these warmer waters, suggesting that temperature alone was not a limiting factor in their range. This challenges long-held assumptions about penguins as strictly cold-water animals and broadens understanding of their environmental flexibility.
However, the species vanished as the Pleistocene ice ages began roughly 2.58 million years ago. Sea levels and ice coverage fluctuated as temperatures dropped, and though smaller penguins in the region endured these changes, the giant species disappeared. Researchers are still working to determine why.
Paul Scofield, senior curator at Canterbury Museum and a co-author of the study, said it’s unlikely that cooler temperatures were solely to blame. He noted that crested and little penguins survived the same climate shifts and still inhabit New Zealand today.
One theory suggests that the open coastal colonies where giant penguins likely bred may have made them more vulnerable to predators, such as the now-extinct Haast’s eagle and Forbes’ harrier. These massive raptors arrived from Australia within the last three million years and hunted large prey, including moa.
Extinction questions and environmental clues
Other possible causes include changes in marine ecosystems. While food shortages can have severe impacts on penguins, researchers say it’s unclear why this would have selectively affected only the larger species.
The fossil discovery not only deepens understanding of penguin evolution but also offers a glimpse into how species may respond as ocean temperatures rise. With Aotearoa’s marine ecosystem entering the habitable range for new species, studying past warm periods has never been more relevant.
The team thanked Kerr Sharpe-Young for uncovering the fossil and acknowledged the support of Ngāti Ruanui and Ngāruahine in facilitating the research.
