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Print * Mark A Klingler/Carnegie Museum of Natural History Life reconstruction of Puijila darwini swimming in crater lake. Life reconstruction of Puijila darwini swimming in crater lake.
modern seals, sea lions and walruses -- explaining how the animal group moved from land-dwellers with legs to the semi-aquatic, flippered swimmers around today. "The land-to-sea transition in pinnipeds has been difficult to study because the fossil evidence has been weak and contentious," said Natalia Rybczynski, a paleontologist with the Canadian Museum of Nature who led the expedition that discovered the skeleton. "Puijila is important because it provides a first glimpse into the earliest stages of this important evolutionary transition." The discovery is detailed in the April 23 issue of the journal Nature.
limb adaptations well-suited for gliding through the water in search of a fresh seafood dinner. Paleontologists have long thought that these specialized limbs evolved over time as terrestrial species began testing out life in the water. Charles Darwin himself (for whom the new species was named) predicted this land-to-sea transition in The Origin of Species: "A strictly terrestrial animal, by occasionally hunting for food in shallow water, then in streams or lakes, might at last be converted in an animal so thoroughly aquatic as to brace the open ocean." But until Puijila's discovery, the most primitive pinniped known to science (Enaliarctos) was already fully flippered. Accidental discovery Rybczynski and her team found the skeleton purely by accident during an expedition to the Haughton meteor impact crater on Devon Island, one of Canada's northernmost Arctic islands. The team's vehicle had run out of gas, and the first bone of the animal was found while waiting for team members to return with fuel.
The researchers at first thought that the animal was a prehistoric otter, but when they examined it more closely they found they had a far more exciting specimen that shed light on an important aspect of animal evolution. "The remarkably preserved skeleton of Puijila had heavy limbs, indicative of well developed muscles, and flattened phalanges which suggests that the feet were webbed, but not flippers. This animal was likely adept at both swimming and walking on land," said Mary Dawson, curator emeritus of Carnegie Museum of Natural History in Pittsburgh. "For swimming it paddled with both front and hind limbs. Puijila is the evolutionary evidence we have been lacking for so long." The animal was a four-legged carnivore about 43 inches (110 centimeters) from nose to tail. Along with its webbed feet, it had an elongated, streamlined body that would have allowed it to glide through the water with speed and agility. Its large teeth, short snout and jaw suggest it had a nasty bite. possible preserved stomach contents suggest the animal's last meal included a duck and some type of rodent.
Arctic location where Puijila was once had a cool, coastal temperature environment, similar to present-day New Jersey. "Puijila is the first fossil evidence that early pinnipeds lived in the Arctic," Rybczynski said. "This discovery supports the hypothesis that the Arctic may have been a geographic center in pinniped evolution." The team is planning to go back to the Devon Island site this year to look for more fossils. The Puijila skeleton will be on display at the Canadian Museum of Nature in Ottawa from April 28 to May 10. A model of the fossil will be included in the "Extreme Mammals" exhibition at the American Museum of Natural History in New York, which opens on May 16. The project was supported by the Canadian Museum of Nature, Carnegie Museum of Natural History, American Museum of Natural History, Polar Continental Shelf Program, Northern Scientific Training Program, Government of Nunavut, Qikiqtani Inuit Association and the hamlet of Frise Fiord, Nunavut. This material may not be published, broadcast, rewritten or redistributed.
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