Proneotherium repenningi

Proneotherium repenningi is an extinct pinniped of the walrus family Odobenidae that lived during the Early Miocene in what is now Oregon, in the United States. Four specimens, with cranial and postcranial remains that are all believed to come from adult males, were found in the Astoria Formation of Lincoln County. It looked more like a modern fur seal or sea lion than a walrus, being smaller and more slender than living walruses and lacking their long tusks. Its teeth are less specialised for cutting than those of more basal species, which may reflect a slow shift from a diet of fish to the shellfish diet of the modern walrus, and its hindlimbs show early signs of a more aquatic lifestyle.