Discovery of fossil bones reveals gigantic penguin species in New Zealand

Fossil remains of two recently identified penguin species, with one believed to be the largest penguin ever known, weighing over 150 kilograms, more than triple the size of today’s largest penguins, have been found in New Zealand.

An international team, including researchers from the University of Cambridge, announced the discovery in the Journal of Paleontology. The lead author of the study, Alan Tennyson from the Museum of New Zealand Te Papa Tongarewa, came across the fossils in North Otago, located on New Zealand’s South Island, between 2016 and 2017.

The fossils were revealed from within 57-million-year-old beach boulders by Al Manning. Through analysis, they were determined to be around 59.5 to 55.5 million years old, indicating their existence approximately five to ten million years after the extinction of non-avian dinosaurs, known as the end-Cretaceous extinction.

Using laser scanning technology, the team generated digital models of the bones and compared them to those of other fossil species, as well as present-day diving birds such as auks and modern penguins. By examining hundreds of bones from contemporary penguins, specifically flipper bones, they established a regression equation to estimate the weight of the new species.

Their findings revealed that the largest flipper bones belonged to a penguin that weighed an astonishing 154 kg. To put this into perspective, the heaviest and tallest living penguins, emperor penguins, typically weigh between 22 and 45 kg.

Skeletal illustrations of Kumimanu fordycei, Petradyptes stonehousei, and a modern emperor penguin showing the sizes of the new fossil species. Credit: Dr Simone Giovanardi

According to Dr. Daniel Field, a co-author from Cambridge’s Department of Earth Sciences, fossils can often reveal surprising aspects of the history of life. In this case, the team’s findings on ancient penguins were truly astonishing. Dr. Field mentioned that many early fossil penguins were massive, surpassing the size of today’s largest penguins. The newly discovered species, named Kumimanu fordycei, holds the title of the largest fossil penguin ever found. Weighing approximately 350 pounds, it would have exceeded the weight of basketball player Shaquille O’Neal during his dominant years.

The team chose to honor Dr. R. Ewan Fordyce, Professor Emeritus at the University of Otago, by naming the species Kumimanu fordycei. Dr. Daniel Ksepka, the first author from the Bruce Museum in Greenwich, Connecticut, expressed gratitude towards Dr. Fordyce, describing him as a legendary figure and an exceptionally supportive mentor. The team recognized that without Dr. Fordyce’s field program, many iconic fossil species would remain unknown.

In addition to Kumimanu fordycei, the researchers discovered multiple specimens of another penguin species. This second species, named Petradyptes stonehousei, weighed 50kg, making it smaller than Kumimanu fordycei but still larger than an emperor penguin. The name Petradyptes stonehousei combines “petra,” meaning rock in Greek, and “dyptes,” referring to a diver, highlighting the preservation of the diving bird within a boulder. The name “stonehousei” pays tribute to the late Dr. Bernard Stonehouse (1926–2014), who achieved a significant milestone in penguin biology by observing the complete breeding cycle of the emperor penguin.

These newly described species indicate that penguins achieved remarkable sizes early in their evolutionary timeline, long before they developed the refined flipper structures seen in modern penguins. The researchers noted that the two species retained primitive features, including slender flipper bones and muscle attachment points reminiscent of those found in flying birds.

Emperor penguins on Snow Hill. Credit: Denis Luyten

Dr. Daniel Ksepka, when asked about the reasons behind the early penguins’ colossal growth, speculated that their large size provided several advantages, particularly in the water. He explained that a bigger penguin could capture larger prey and, more importantly, would have been more adept at regulating body temperature in cold aquatic environments. It is also possible that surpassing the 100-pound size barrier enabled the early penguins to expand their range beyond New Zealand to other regions worldwide.

Co-author Dr. Daniel Thomas from Massey University in Auckland emphasized the importance of considering these fossil finds as parts of complete living animals. He noted that present-day large, warm-blooded marine creatures can dive to significant depths, raising questions about whether Kumimanu fordycei had an ecological niche distinct from that of modern penguins. It is possible that this ancient penguin had the ability to access deeper waters and find food sources that are currently inaccessible to living penguins.

Describing Kumimanu fordycei as an astonishing sight on the ancient beaches of New Zealand, Dr. Daniel Field, who is both a co-author and the Curator of Ornithology at Cambridge’s Museum of Zoology, highlighted the intrigue surrounding this species due to its sheer size and the incomplete nature of its fossil remains. He expressed hope that future fossil discoveries would provide further insights into the biology of this extraordinary early penguin.

Source: University of Cambridge

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