With the rain driving us off the site, we set up a makeshift preparation lab in the hotel room and spent the day cleaning some of the fossils collected last week. In attempting to trench around the whale skeleton, we’ve had to remove numerous bones from the trench (there are still at least 5 bones in the trench awaiting removal). Three of the bones are from the flipper:
The bone on the right is one of the phalanges (finger bones). This one was crushed into the transverse process of a vertebra that was also removed (see Day 4).
I originally thought the other two bones were also phalanges, but now that I’ve cleaned them I think they are probably metacarpals (hand bones).
Here’s the vertebra that had to be removed, after being cleaned up:
This image is from in front and above (anterodorsal view). The left transverse process (on the right side of the image) is the one that was crushed against the phalange. The neural spine was missing (as this whale is upside down, the top of the neural canal was against the Eocene-Miocene contact). There were several flat bones adjacent to this vertebra that we also removed; it’s possible that one of them may be the detached neural spine.
Turning the vertebra over, we can see two features that identify this as a lumbar vertebra:
First, “A” is pointing to the essentially undamaged right transverse process. There is no facet at the end of this process for articulating with a rib, which rules out this being a lumbar vertebra. Second, “B” is pointing to the sharp ridge (the hypapophysis) that runs along the ventral margin of the vertebra. The hypapophysis in this case is a single sharp ridge. If this were a caudal vertebra, the hypapophysis would be bifurcated and have articular surfaces for the attachment of the chevron bones (see the photo of a caudal vertebra from Day 3).
There’s more rain in the forecast for tomorrow, but we’re still hoping to get in for at least part of the day.
For those interested in critters that have not yet become fossils, Tim is doing more entries on his blog about the wildlife in the area.