Today we began preparing the femur for its top jacket. I’ve been a bit worried about removing this bone, because of the way in which it’s preserved. The bone is badly fractured just distal of the midpoint, and the most distal part (near the knee) is mostly missing on one side. In the photo below, distal is to the right:
The preservation itself is kind of interesting. This bone sits high in the bonebed; the break is about as high as any bones we’ve found. Note that the bone is angled upward toward the break. The bone around the break is displaced to the side:
I think when this bone was buried in the mud, only the proximal end was buried; the distal end was sticking up out of the mud. While sticking up in the air, I think something happened to snap the bone; perhaps it was stepped on by another sauropod, or maybe by a scavenger (although we haven’t found any shed teeth from carnivorous animals so far). Broken, but still exposed, the bone deteriorated and fell apart, except for the portions still buried in the mud (including the posterior surface of the distal end, which was pushed into the mud when the bone was broken).
If there are any taphonomists reading this, feel free to take some shots at my elegant hypothesis!
(*Arm-waving bout ends*)
At any rate, this fracture and displacement of the bone makes jacketing difficult. We covered the bone with toilet paper (as a separator) as we usually do:
I’m still not 100% sure this jacket is going to work. We’ll find out tomorrow, as we intend to flip the jacket first thing.
We also made the bottom jacket for yesterday’s vertebra: