Well, we finally have them removed. The bone that was removed is very interesting, It resembles a folded premade taco shell, with smooth bone surface as the tortilla and a filling of bone and matrix with a hollow surface. It has hole through it. It is roughly square about 6 cm on a side and about 2 cm thick. One side is a curved bone surface from front to back. The other 3 'sides' look like the hollows found on the ends of the long bones - hollow cavities with knife-thin edges of bone lining them. What I think we have here is a fused ischium/pubis bone like that found in an Ophthalomosaurus (Handbook of Paleoherpetology,m Vol 8, pg 40) with the edges facing other bones incompletely ossified.
This bone will require some more cleanup on the incompletely ossified sides, but is certainly one of the more interesting ones! The bone along the rim of the 'taco shell' is less than 1mm thick!
This has exposed much more of the very large bone that I suspect is part of the skull. We have 'chased out' the bone along the larger axis, and found it connects to a hollow on the original outer surface of the concretion that had bone showing. It stretches the full width of this picture - over 30cm long. It is well over 10 cm wide and we haven't found the inside edge. Jerry and I both have spent a full day excavating barren matrix from the outside edge of the block, and we'll have several more weeks removing it. This matrix (here at the top of the picture) will all have to be removed to get at the 'outer' edge of the large bone, and eventually behind it. There is one centrum (backbone) at the right end, and another Nautiloid is appearing at the left end, both to be watched and removed as possible. The top of the larger Nautiloid was removed to allow us access to remove the ischium/pubis, and it's being kept safe for re-attachment (probably this next week).
Several other smaller bones have been removed and need to be cleaned up as time permits.
More updates. As I tell folks, the work is meticulous, but not tedious - it's always a challenge and very interesting. Sincerely, Greg Carr