A potential ‘missing link’ in the evolution of seals has been discovered. A new fossil described in Nature shows features suggesting it was semi-aquatic, but had not yet fully accepted the sea as its home.

Named Puijila darwini, the animal has the long tail and limbs of a terrestrial carnivore but other features, such as indications of webbing on the feet, suggest an affinity for water. Previously the earliest pinniped – the group that includes seals, sea lions and the walrus – was an animal that already had flippers.

According to Natalia Rybczynski, of the Canadian Museum of Nature, interviewed on the Nature Podcast, the animal was “something like a river otter, but much more muscular” and was “almost a wolverine that could hunt on land and also in water” around 21 and 24 million years ago.

“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,” says paper author Mary Dawson, of the Carnegie Museum of Natural History (press release). “This animal was likely adept at both swimming and walking on land.”

P darwini was uncovered in the Arctic, and all thanks to someone not filling up the gas tank. The Canadian Museum of Nature explains that an ATV became bogged down in mud and ran out of gas in 2007 at the end of a day’s work on Devon Island. While some of the researchers went to get more fuel, others scuffed around in the soil and unearthed the proto-seal.

“The discovery suggests that the evolution of pinnipeds included a freshwater transitional phase, and may support the hypothesis that the Arctic was an early centre of pinniped evolution,” the research team write in Nature.

The paper also explains the name, with is more than just a Darwin 200 cash in:

Etymology. Puijila (Inuktitut): young seamammal, often referring to a seal; darwini: for Charles Darwin, who wrote with his usual prescience [in On 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 into an animal so thoroughly aquatic as to brave the open ocean”

More coverage

Otter-like fossil reveals early seal evolution – AP

Arctic discovery provides ‘missing link’ for seals – AFP

Scientists find ‘missing link’ in seal evolution – The Canadian Press

Missing link fossil shows how seals got flippers – Times

Puijila also features on this week’s Nature Podcast.

Image top: reconstruction of Puijila darwini / Mark A. Klingler of Carnegie Museum of Natural History

Image lower: Puijila skeleton / Martin Lipman.