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Potamotherium (Wikimedia Commons)


Potamotherium (Greek for "river beast"); pronounced POT-ah-moe-THEE-ree-um


Rivers of Europe and North America

Historical Epoch:

Miocene (23-5 million years ago)

Size and Weight:

About 5 feet long and 20-30 pounds



Distinguishing Characteristics:

Slender body; short legs


About Potamotherium:

When its fossils were first discovered, way back in 1833, no one was quite sure what to make of Potamotherium, though the preponderance of the evidence pointed to its being a prehistoric weasel (a logical conclusion, given this megafauna mammal's sleek, weasel-like body). However, further studies have relocated Potamotherium on the evolutionary tree as a distant ancestor of modern pinnipeds, a family of marine reptiles that includes seals and walruses. The recent discovery of Puijila, the "walking seal," has sealed the deal, so to speak: these two mammals of the Miocene epoch were clearly closely related to each other.

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