As a group of Canadian paleontologists were on their way home from a long day out in the Arctic collecting fossils of vertebrates, one student discovered a shin bone in the ground so she started to dig it up. All of the fossil pieces were collected and brought to the lab to be essembled. At first, they were unsure of what this animal could be but as they were putting together the pieces, it had a jaw and skill like a flipper-less primitive pinniped. It turned out that these bones were of a sea otter with webbed feet from 20-24 million years ago. Its body was like present day sea otters that are able to swim but these fossils indicated that the creature spent most of its time on land.
Before this discovery, seals, walruses and sea lions did not have webbed feet, they had flippers. There was an evolutionary gap of the origin of pinniped mammals evolved from land to sea. The most primitive pinniped fossils, which date to between 20 million and 28 million years ago, had full flippers, making it hard to pinpoint how the animals evolved to live in an aquatic environment (Grom 2009). Almost all sea mammals originated on land which meant they were able to walk and had legs. This discovery of the webbed-feet sea otter, Puijila darwini, helped reveal what the ancestors of seals, walruses and sea lions looked like before they had flippers.
Citation Information
Grom, Jackie. 2009 Arctic Fossils Reveal “Walking Seals” ScienceNOW Daily News[Internet] Washington DC and Cambridge, UK: High Wire Press; 2009 [cited 2009 May 21]. Available from http://sciencenow.sciencemag.org/cgi/content/full/2009/422/1
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