Potamotherium


Potamotherium an extinct genus of caniform carnivoran from the Miocene epoch of France and Germany. It has been previously assigned to the mustelid family, but recent work suggests that it represents a primitive relative of pinnipeds.

Classification

The genus was first described in 1833. Carroll assigned it to the family Mustelidae as a member of the subfamily Oligobuninae. However, it was recently suggested that Potamotherium was not a mustelid at all, but rather a very basal pinniped. Berta et al. placed Potamotherium along with Puijila and Semantor in the family Semantoridae.
Two species have been identified in the genus: P. valletoni, the type species, and P. miocenicum.

Distribution

Finds range from the mid-latitudes of Europe and North America, dated from the Oligocene/Miocene boundary and surviving through to the end of the Miocene. It has been interpreted by several researchers as a basal, non-marine ancestor of seals and sea lions, suggesting a freshwater phase in the evolutionary transition of pinnipeds from land to sea. If Potamotherium was indeed a pinniped instead of a mustelid, its relatives were possibly early bears.

Palaeology

Physically, Potamotherium resembled a modern otter, and was long, with an elongated, slender body and short legs. With a flexible backbone and a streamlined shape, it was probably a good swimmer. Analysis of fossils suggests that Potamotherium had a poor sense of smell, but made up for this with good vision and hearing.