A penguin as heavy as a gorilla. The startling discovery on the east coast of New Zealand’s South Island revealed a penguin species of colossal size, leaving scientists astonished. The remains date back to about 57 million years ago, and their weight places this bird among the heaviest penguins ever known. With an estimated mass near 160 kilos, it stands as the heaviest penguin documented by science.
Alan Tennyson, a paleontologist associated with Te Papa Tongarewa Museum in New Zealand, uncovered the bones of large seabirds with his son in 2017. Three distinct, previously unknown penguin species were identified from those finds.
The remains were found on a beach famous for the Moeraki rocks, the large boulders that line this coast. The power of the tide revealed fossilized bone fragments inside these rocks. Upon study, researchers confirmed the existence of three new, undescribed penguin species, with one possibly exceeding the size of any living penguin.
“Fossils provide a window into the history of life, and sometimes the evidence is truly surprising,” remarks Daniel Field of Cambridge Earth Sciences. “Many of the earliest fossil penguins grew to gigantic proportions, easily surpassing the size of today’s largest penguins.”
The scientific report detailing these prehistoric giants appears in a paleontology journal. The largest penguin is named kumimanu fordycei. Kumimanu derives from the Maori term meaning “monster bird,” while fordycei honors Dr. Ewan Fordyce. The smallest penguin was named petradipts, meaning “rock diver” in reference to its rocky habitat.
“Ewan Fordyce is a legend in the field and a generous mentor. Without Fordyce’s field program, many iconic fossil penguins wouldn’t be known, so it feels fitting that a penguin bears his name.”
How did researchers estimate the weights of these giants? They built three-dimensional models and compared bone size and density to those of modern penguins. According to their analysis, P. stone house would weigh about 50 kilograms, slightly more than emperor penguins alive today, Aptenodytes forster. In contrast, K. fordeycei could reach up to 160 kilograms, more than three times that figure.
The oversized frame likely offered advantages in the water. Researchers suggest that a larger penguin could seize bigger prey and better regulate body temperature in cold seas, contributing to its aquatic edge.
The appearance of such giants follows the mass extinction event that occurred around 66 million years ago, when the Chicxulub impact ended the reign of non-avian dinosaurs and left mammals to rise. With fewer large marine reptile competitors, penguins could occupy a broader ecological space and grow to remarkable sizes. It remains uncertain whether even larger penguins existed or if the discovered remains simply represent an especially giant specimen.
Reference work: https://www.cambridge.org/core/journals/journal-of-paleontology/article/largestknown-fossil-penguin-provides-insight-into-the-early-evolution-of-sphenisciform-body-size-and-flipper-anatomy/8D4A78B2CA0A716134F8E60169A633FD
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The team notes the importance of fossil records in tracing the evolution of flightless flight structures in ancient penguins and how these giants fit into broad patterns of cetacean and avian evolution during early Cenozoic oceans. This work highlights the dynamic history of life on the planet and how giant penguins once dominated the cold seas, filling niches left by the disappearance of other large marine vertebrates.
Audience and researchers credit Cambridge Earth Sciences for the interpretation of the fossil record and the development of methods that reveal how body size shaped ancient penguin biology. The findings underscore how paleontological discoveries continue to reshape our understanding of penguin evolution and marine ecosystems across deep time.