Wednesday, May 25, 2016

Two more skull pieces!

So right now I'm working on a block at home and a block at OMSI. The block at home was originally located close to the original skull, about 10 inches (25cm) away. It is a lovely little block with a whole cluster of centrum (backbones) at one end, plus most of a large neural arch with some ribs thrown in for good measure. I think there are 8 or 9 centrums. Although they look like they are articulated, they are not. They are different sizes and orientations so they came from different individuals or different parts of the backbone. Too bad. Anyway, I was going to keep the block pretty intact and leave it as an esthetic piece since we already have good single specimens of all these bones.

At the other end of the 'home block' there were initially two small fragments of bone glued back on. The way this works is that a smaller block is broken off a larger block so we can work on it, usually along natural fracture lines. The bones that cross the fracture surface are removed from the smaller block and glued back onto the other block, so that the bones are made whole again. So we started out with two small bone fragments separated by about 3 inches (7.5cm). Preparing these small pieces of bone did not immediately make clear what they were. But it did become clear that they were parts of the same bone. One side of the bone is now prepared, and it is another section of a skull centered around the pineal gland. I think this makes it the 5th specimen we have from this section of skull! And first measurements indicate that it is the largest to-date! It is amazing how a piece of bone 5.5 inches (14cm) can hide in a block of rock almost completely when the rock is only 7x10 inches!

So I'll have to remove this skull fragment from the block for scientific study. The other end with all the centrums can remain intact as a showpiece, unless something else comes up!

As for the other skull piece, it's at OMSI. I started on a new section of block 1 and uncovered the end of a strange item. I couldn't really tell if it was a piece of bone or a piece of coral. It was not as dark as normal bone, but had the correct internal structure. It did not power up black when touched by the air scribe - it was grey like coral. I decided to treat is as a bone . I'm glad I did since it turned out to be a nice limb bone.  There was a 'small spine' next to the limb bone that looked like a neural arch. 

When I got the limb bone undercut and ready to remove there were some small scraps of bone showing at the bottom of the cust. After knocking off the limb, I realized that I had broken completely through the lower end of the 'small spine". It is not a neural arch, as it is rapidly expanding into a big section of bone. It is a piece of skull, I think it is the middle along the centerline. We will tell more as we excavate more. Unfortunately, it will require practically cutting the big block completely in half as it is imbedded directly in the middle, pointing straight into the center!
Sincerely, Greg Carr

On the left we have the skull piece  - the reminder is still in the block. The right piece is the limb bone. 

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