Fossil of sea mammal to be highlighted at San Mateo County’s museum expansion

When the San Mateo County History Museum finishes a remodel and expansion in mid-2026, one of the most interesting items that will go on display will be a plaster cast of a sea mammal that last swam in the county 14 million years ago.

The cast is a reconstruction of actual fossilized bones that were found in 1964 by construction workers excavating the Stanford Linear Accelerator Center in Menlo Park. The original bones are now stored at the campus of University of California, Berkeley.