As we move the Diorocetus specimen out of the lab, new projects are moving in. Here is my next top priority – a massive lower jaw from Carmel Church. This specimen had been way down on my “to-do” list, but jumped to the top when I decided to do my SEAVP presentation on it.
I think this is the lower jaw from Eobalaenoptera, the first whale ever found at Carmel Church. In fact, we provided this jaw to RCI to use in making the Eobalaenoptera cast hanging in the museum’s Great Hall:
- Using the skull fragments from the type specimen and the Smithsonian skull, we calculated about how long the lower jaw should be, and this specimen is exactly the predicted length (and we really did it in that order). Moreover, Eobalaenoptera is the largest described whale from the Calvert Formation; only Pelocetus approaches it, but it’s still not as large. There may also be another large, unnamed mysticete from the Calvert that approaches this size, known from one specimen, but it’s still smaller.
The specimen is from Carmel Church, which is the type locality for Eobalaenoptera. It was actually found in 1991 when we were excavating the holotype, about 200 feet away (no way they’re from the same individual, though). Here’s the dentary during excavation:
- Although we excavated the dentary, we didn’t do any large-scale follow-up excavation at the same spot. We did find some other heavily-weathered bones in about the same area (within about 2 meters) over the years, though. These included a few large vertebrae, consistent with Eobalaenoptera, an enormous vomer (not preserved in the other specimens), and a tympanic bulla. The bulla is similar to the type Eobalaenoptera bulla. It’s also similar to the much smaller Aglaocetus patulus (an interesting feature of Eobalaenoptera is that it has tiny tympanic bullae for the size of the animal).
So, is this dentary really from Eobalaenoptera? It’s certainly not a slam-dunk, but it looks pretty good, although I can’t definitely rule out Pelocetus or some unnamed large mysticete at this stage.