Tuesday, 28 February 2012
The bones of a giant penguin fossilised in a Waimate cliff have been reconstructed at the University of Otago’s Geology Department, giving researchers new insights into the prehistoric creature.
The giant penguins - which scientists have dubbed Kairuku - are featured in the cover article published today in the Journal of Vertebrate Paleontology. Kairuku stood 1.3 metres tall – 30 cm taller than its nearest modern-day rival, the Emperor Penguin, of Antarctica. With its spear-like bill, it weighed at least 60 kilograms, which is 50% heavier than the Emperor Penguin.
At least four individual Kairuku penguins are known. The first find involved 27-million-year-old fossilised bones spotted “by chance” in a cliff near Waimate, South Canterbury, in 1977 by Professor Ewan Fordyce, a paleontologist from the University of Otago.
At that time, Fordyce was a PhD student looking for fossil whale bones. Returning to Otago as a staff member in 1982, he went back and removed the rest of the bone fossils that were embedded in the rock. Other finds followed in the 1990s and, most recently, 2011. The specimens are now displayed in the Geology Museum.
Remains of "giant" penguins were first recovered from New Zealand as long ago as the 1840s. Until now, however, there were no reasonably complete specimens.
In 2009 and 2011, Dr Dan Ksepka, of North Carolina State University, was invited to Dunedin to aid in the reconstruction of the giant penguin fossils. Dr Ksepka is the article’s first author.
Professor Fordyce, who led the research project, says the finds are very exciting for penguin biologists and those interested in the origins of seabirds, and provide a significant boost to what is known internationally about the history of penguins.
Finding such specimens offered the “...chance of a lifetime to better understand those extinct penguins that lived before the earliest fossils of "modern" species, more than 15 million years ago.”
“For the first time we have been able to publish really clear evidence about the body size and proportions of these older penguins,” he says.
The Kairuku – a Māori word loosely translated to “diver who returns with food” - probably became extinct from its New Zealand habitat between 24 and 25 million years ago.
Professor Fordyce says its large body size was an “adaptation” for swimming further and diving deeper compared to its modern-day counterparts. Researchers are not sure why the "giant" penguins disappeared. Climate change, or increased predation from dolphins and seals, has been suggested as possible causes of extinction.
Dr Fordyce says New Zealand has a history of producing exceptional fossils that give important insights into the history of penguins and other marine creatures.
“When the penguins lived about 27 million years ago, New Zealand seas probably offered a rich supply of food, with good nesting sites nearby. The penguin skeletons were buried in quiet conditions, without being broken apart by waves and currents. As a result, the fossils are well preserved and complete,” Professor Fordyce says.
Dr Ksepka says the New Zealand location was great for penguins in terms of both food and safety.
“Most of New Zealand was underwater at that time, leaving isolated, rocky land masses that kept the penguins safe from potential predators and provided them with a plentiful food supply," he says.
Kairuku includes two species of at least five different species of penguin that lived in New Zealand during the same period. The diversity of species is part of what made the reconstruction difficult, and the penguin's unique physique added to the difficulty.
"Kairuku was an elegant bird by penguin standards, with a slender body and long flippers, but short, thick legs and feet," says Dr Ksepka.
"If we had done a reconstruction by extrapolating from the length of its flippers, it would have stood over 6 feet tall. In reality, Kairuku was around 4-feet-2 inches tall (1.3 m) or so."
The researchers reconstructed size and proportions in Kairuku from two main fossils, using the skeleton of an existing king penguin as a model. The result is a tall bird with an elongated beak and long flippers – easily the largest of the five species that were common to the area in that time period.
Dr Ksepka hopes that the reconstruction of Kairuku will give other paleontologists more information about other fossils found in that area, as well as add to the knowledge about giant penguin species.
The research was funded by the University of Otago, the National Geographic Society, and the National Science Foundation.
List of authors
Daniel T. Ksepka, North Carolina State University and the North Carolina Museum of Natural Sciences; R. Ewan Fordyce, Tatsuro Ando, Craig M. Jones, Department of Geology, University of Otago, New Zealand. Ando is now at Ashoro Museum of Paleontology, Hokkaido, Japan; Jones is now at GNS Science, Lower Hutt, New Zealand.
Published: Feb. 27, 2012, in the Journal of Vertebrate Paleontology
For further information, contact
Professor Ewan Fordyce
Department of Geology
University of Otago
Tel 64 3 479 7510
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