What kind of bone is this?

I came across a bone while I was walking on the beach.  Do you know what animal it came from and what part it is?  Thanks!

Dawn, Goleta (bone found at Haskells, going west) - December 7, 2018

Curator Response

Hi Dawn,

Interesting find! Although it’s hard to tell without anything in the photo to show how large this is, this looks to me like a cleithrum, which is a bone that fish have in the structure known as their pectoral girdle. Muscles that control the pectoral fin—the one that’s usually right behind the gills in many fishes—attach to these bones. In the photos, it appears there is another, smaller bone still attached to the cleithrum (possibly a hypercoracoid bone, another part of the same structure).

The shape of the cleithrum varies across species. We looked at quite a few of these bones in our collections, but didn't find one precisely like this, so we can't narrow it down to a particular species.

Paul W. Collins, Curator of Vertebrate Zoology