I work for a public museum (VMNH is a Virginia state agency), so part of my job is answering questions from the public about paleontology. This usually takes the form of identifying “fossils” that people have found in a local stream or some other unlikely place. About 90% of the time they’re mistaken, and I’m left with the unenviable task of telling someone that their prized fossil is, in fact, a rock. But every now and then I get something different.
Last week Francis Deboever sent me a series of photos of a supposed fossil; the verdict from some online forums was that it was a whale rib. This one really is a bone, and it’s from a whale, but it’s not a rib. This is a segment of a dentary (lower jaw) from a baleen whale. Several mental foramina, which are typical of whale dentaries, are visible along the dorsal margin, as indicated by the arrows below:
While most parts of baleen whale skulls are somewhat fragile, dentaries are actually rather tough. Fragments show up frequently along the rivers on the Virginia Coastal Plain, usually having weathered out of either the Calvert, Eastover, or Yorktown Formations. So Francis has a nice, but rather common, baleen whale lower whale jaw. What, then, makes this bone special? This bone was found in Harriston, Virginia:
Harriston is located in the mountains, more than 80 miles from the nearest coastal plain sediments! How did this whale manage to make its way to the Blue Ridge? The probable answer is actually included in Francis’ email:
“[It] appears to have washed out from under an old concrete slab that I believe covers the debris from an old concrete well.”
The Miocene and Pliocene deposits along the James River used to be quarried fairly extensively. These are soft sediments that are extremely rich in mollusk shells, and they were mined for a variety of purposes, including fertilizer, fill dirt, and making concrete. It’s very likely that the well was constructed from concrete made from a load of Eastover or Yorktown sediment transported in from a quarry near the James River, and that happened to include a whale jaw fragment among the sediment.
Thanks to Francis for bringing this specimen to our attention, and for giving me permission to post the photos on the blog.