Arctic fossil is the missing link that shows how seals went from land to sea

pujila1Wednesday, 22nd of April 2009, a member of a team of scientists said that they have discovered in Canada’s Arctic the fossil of a previously unknown web-footed carnivore that helps explain how seals developed from land-based mammals. The very primitive animal, measuring around 110 cm (43 inches) from nose to tail, had a body similar to that of an otter, with a skull more closely related to a seal. It lived in and around fresh water lakes about 20 million to 24 million years ago. The mammal, named Puijila darwin, could move easily on both land and water and is a member of the pinniped family, which groups seals, sea lions and walruses. Puijila was a carnivorous mammal with large canine teeth, a short snout and a powerful jaw. It had an elongated streamlined body, webbed feet and a tail that enabled it to move through the water at speed.
“Our animal fills that transitional gap between the land form and the marine flippered form we’re familiar with today,” said Natalia Rybczynski of the Canadian Museum of Nature.
The team hopes to find out in the future expedition to Arctic why and how the Puijila came to lose its long tail during the evolution.
“Other mammals that went from land to sea, like whales and manatees, retained and made good use of their tails, (which) became propulsive structures. For some reason the pinniped lineage didn’t do that, and now we know they had had the option … they had the tail but didn’t use it,” said Rybczynski. “The idea hasn’t been that there was this phase where they were living on the continent in streams and lakes. So that changes our idea about how these animals came to be,” said Rybczynski. At the time, the Arctic was forested and much warmer than it is today. “One explanation could be that Puijila gradually moved further south or that the animal found in the Arctic had come originally from the west coast. Parallel evolution (the same process taking place in another part of the world at the same time) is also a theory.” “”We do have this most primitive form that we’re finding in the Arctic so we also must consider the hypothesis that the Arctic was a place where these things could have been deriving from as well,” Rybczynski said.


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