Since John Parker delivered a small Miocene sperm whale jaw to the museum last week, our volunteers have been eagerly removing sediment to expose the jaw. Without the mess of bones, rocks, and difficult geochemistry at Carmel Church, Calvert specimens actually prepare pretty quickly, and the jaw is already well on the way to being completed (above). Here’s a marked-up version of the same image:
This is the medial (inside) of the right lower jaw (or right dentary). Red arrows are indicating teeth that are still in their sockets, while the blue arrows are detached teeth. The occlusion wear on the teeth indicate that this whale had functional upper and lower teeth (unlike modern sperm whales, which only have functional lower teeth). Because of this, it’s not yet clear where these teeth came from. They could be from further back in this dentary, they could come from the left dentary, or they could be upper teeth.
The purple arrow is indicating the mandibular condyle, the part of the dentary that articulates with the cranium. That shows that we have the entire back end of the jaw; the front tip (at left) had already weathered away when John found the specimen. There’s quite a bit of breakage in the thin bone at the back of the jaw, just anterior to the condyle.
I expect that we’ll have the entire medial side of this bone cleaned by tomorrow afternoon. If the breaks at the back of the jaw aren’t too bad, we may be able to complete the preparation in a week or two.