Hey all, I'm posting this in acknowledgment of Christopher Pirrone's donation - he is @oreodont but I'm not sure he posts here that much any more. Chris was generous enough to mail this specimen to NZ in 2014 while I was doing my Ph.D. so I could prepare and study it. I molded and casted the specimen for him. Sea otter fossils are as rare as hen's teeth.
Enhydra sp.
Merced Formation, middle Pleistocene (670-620 Ka)
San Francisco, California, USA.
Donated to University of California Museum of Paleontology, Berkeley, CA.
This specimen was collected from a well-dated horizon in the Merced Formation and constitutes the earliest example of a true sea otter (Enhydra) in the Pacific basin, indicating that sea otters are a recent invader from the Arctic/North Atlantic. Here's the paper: http://link.springer.com/article/10.1007/s10914-016-9373-6