A happenstance fossil find is shedding new light on the evolution of pinnipeds -- the group that includes seals, sea lions and walruses -- and backing up a key prediction Charles Darwin made about their evolutionary pasts.

Natalia Rybczynski, a vertebrate paleontologist with the Canadian Museum of Nature, said the discovery was made after the ATV she and her crew were travelling in ran out of gas on Devon Island, Nunavut, two summers ago.

Rybczynski and another team member went to get gas, leaving behind her assistant, Carleton University student Elizabeth Ross, and Mary Dawson, curator emeritus of the Carnegie Museum of Natural History in Pittsburgh.

"Liz was a little upset with herself because she was supposed to put fuel in the tank and she hadn't," Rybczynski told CTV Newsnet.

"She's looking at the ground and she sees a little piece of bone and she hands it to Mary and Mary says 'Indeed that's a fossil.'

"... They go back to where Liz had been and strewn across the surface were these mandibles and limb bones -- this black fossil bone -- that was this new animal."

The scientists found about two-thirds of the skeleton of what they later determined could only have been part of the pinniped family tree, some 20 to 24 million years ago.

The animal, the scientists say, was a "walking seal," with both legs and webbed feet.

It was found in the remains of a presumed former freshwater lake, where the evidence suggests the animal likely lived.

The High Arctic fossil find represents a pinniped type that existed in between the land-based pinnipeds from millions of years ago and the flippered pinnipeds of today.

Darwin himself had predicted the existence of this animal in his seminal On the Origins of Species, which was published 150 years ago.

Until the "walking seal" skeleton was found by Rybczynski and her crew, there was no prior evidence that pinnipeds lived in Canada's High Arctic. The find may signify that the region was a centre of evolution for some early pinnipeds.

The animal, since named Puijila darwini, is believed to have been a four-legged, semi-aquatic creature that would have been about 1.10 m long.

With an elongated, streamlined body and webbed feet, the Puijila darwini would have been able to move through water quickly and proficiently, the scientists say. It had a thick neck and muscular shoulders.

Its large canine teeth and short snout were connected by strong jaw muscles, which would have allowed the Puijila darwini to snap its jaws when hunting on land or in the water.

Because it had such sharp teeth, it may have been a carnivore, the scientists say.

The Puijila darwini is the oldest and most primitive pinniped skeleton found to date, though the scientists say it is not a direct relative of today's seals.

Instead, they believe modern seals, as well as the Puijila darwini likely evolved separately from a common ancestor.

The full implications of the Puijila darwini finding have been detailed in a new report that will be published in tomorrow's edition of Nature.

The Puijila darwini skeleton will be on display at the Canadian Museum of Nature from April 28 to May 10.

From there, a model the skeleton will be included in an exhibition at New York's American Natural History Museum, which opens May 16.