I found this bone today in Edgecombe County North Carolina on the Tar River, upper Yorktown Formation, Rushmere member. The area is well known for Chesapectens along with other bivalves and gastropods.    I looked at the Smithsonian publication,  Geology and Paleontology of the Lee Creek Mine, North Carolina, III. Miocene and Pliocene Birds from the Lee Creek Mine, North Carolina. Storrs L. Olson and Pamela C. Rasmussen. Issued May 11, 2001. After searching the many plates I found one