The Inside of the Skull Appears

I've been working on cleaning out the inside of the skull, starting from the rear end (posterior) and working forward. So far I've uncovered the pineal gland opening, the (probable) braincase and the insides of the three terminal projections. The quality of the bone is amazing! Everything is intact, the bone surface is clean and there is no apparent distortion. Here is the bottom overview. The teeth and exterior of the skull are at the bottom, the midline is along the top. The remnant of the last nautiloid is still in the middle of the skull, but it won't be there long.

Here is a closer view of the pineal foramen structure and the braincase. The pineal foramen are found in reptiles. It is the groove with a rounded edge descending from the top of the skull (top in this picture too) that is vaguely bullet-shaped. The pineal gland's full function is not well understood. They definitely were a significant part of the brain and required an opening without bone to let in ambient light through skin or a specialized lens. The brain case is immediately next to it to the right side (posterior). It is not real clear in this photograph but the furthest posterior part of the braincase is U shaped (since it's broken in half) for the brain stem to exit. It would be a round hole if whole. 

The U-shaped section might be a little clearer in this shot - at the top. The braincase is the upper projection. 

You can also see how much of the inside of the skull is showing. The skull varies very elegantly in thickness and strength. The thicker section diagonally across the middle is about 1 cm thick, while the part below it is only about 1-2mm thick. Very Fragile! The lower projection is actually the Quadrate where the jaw bone articulates. It had a very large cartilage pad on the inside of the  projection which appears blurry because it points right at the camera at this angle. 

This is a clearer shot of the Quadrate in better profile. You can also see the pineal gland hole in the top of the skull on the right side - it looks like a notch. 

Last of all here's a free-hand shot:

 
I suspect it might be very interesting to do a FEA (Finite Element Analysis) on this skull to determine things like biting force, etc. The bone thickness is easy to measure (not just estimate) and the angles and curves are beautiful and elegant too.

Sincerely, Greg Carr

The skull, the half skull and nothing but the skull (so help me God)

Well, we have finally gotten all the extraneous stuff off the skull. I think we totaled 6 Nautiloids, 2 ammonites and 8 bones that were attached to the skull when it was removed. The only thing left not of the skull is a part of the last nautiloid that can't be removed intact. That will have to be 'blown away' since it touches the skull interior bone in multiple places. It can't be worked free without damaging the skull - and the skull is ALL-IMPORTANT! I have put in about 50 hours removing all this stuff so far.
The best thing about removing part of the nautiloid is that the interior septums of the chambers can be seen. These nautiloids do not have a completely smooth septum - they are partially convoluted like ammonites. However the siphuncle is toward the middle of the shell, where ammonites have theirs at the very outside of the shell. This proves they really are nautiloids. These will be speciated later by someone who knows what they are doing.

So anyway here are some more pictures of where we are. Interior view, anterior (front) to the left. The remnant nautiloid is the funny lump over the middle of the ruler.

 Here it is rotated,. The three projections at the posterior end show up really well. One is in the center. It will be paired with one on the other side of the skull, perhaps will be the base of the occipital condyle where the backbone hooks to the skull. The outermost one is where the jaws hinge. There appears to be a lightly ossified cartilage area on the inside of this part of the bone. The center one - who knows?

 Here is the outside of the skull - you've seen it before.

 This too - shows the teeth in the jaw line better.

 Here's a close up of the three rear projections. The last centrum was nestled between all three of these and occupied over 1/2 of the volume. It  was difficult to remove it without harm to the skull.

 And here's a view from the rear looking forward. The U-shape of the hollow skull is visible in the dark bone, which is the rear rim of the skull with matrix removed.

I'm looking forward to removing the rest of the matrix and seeing what the rest of this thing looks like!
Sincerely, Greg Carr