Sea lions, weasels and bears oh my!

Photo credit: Thomas Mattern

Classifying animals is a messy business. Back in the day before genetic analysis, seals, sea lions and walruses were classified as members of the order Pinnipedia. They were considered to be “separate from but closely related to the terrestrial carnivores of the order Carnivora” as told by the Encyclopedia of Marine Mammals.

And of course the whole ear thing played a role. Pinnipeds with ear flaps, sea lions and fur seals, were considered to share a common ancestor with bears, while true seals without ear flaps were considered to be more closely related to weasels.

Then came along the ability to inspect animals at the microscopic level, which should have cleared everything up, but alas instead it just made things more confusing. Now the only things scientists agree on is that all pinnipeds descended from the same ancestor and should be classifed within the order Carnivora and the suborder Caniformia. But where they belong within the suborder Caniformia is an entirely different question.

One group of scientists favor a sister group to the bears while other study results support a closer relation to the weasels. Dale Rice, author of the article on classification for the Encyclopedia of Marine Mammals, agrees with a paper from 1997 by McKenna and Bell. They classify “pinnipeds as the superfamily Phocoidea and the bear-like terrestrial carnivores as the superfamily Ursoidea, both under the parvorder Ursida.” So it seems that pinnipeds and bears ended up in sister superfamilies.

Weasels are categorized in their own parvorder Mustelida. And just to help clarify, according to a parvorder is “a specific taxonomic category above superfamily and below infraorder.” The bottom-line, as of the writing of this post, is that seals, sea lions and walruses are more closely related to bears than weasels. Hopefully that cleared things up, just a little.


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