Tuesday, August 8, 2017

A Really Great Pelvic Bone

I have just finished prepping out a really great pelvic girdle bone - probably a Ischium. Reptiles have 3 bones on each side making up the pelvic girdle. In mammals these are fused into the the pelvis, but in reptiles they are the Ischium, Illium and the Pubis. It is the second largest bone I've prepared, second only to the skull. We have had another one, but that one was partially broken and considerably smaller. This one is very large, about 14cm (5.5 inches) long.

So here are the two bones (brown one is a copy) for comparison. The new bone is much larger and very robust. It still shows the typical hollow ends, indicating the bone has a cartilage end, not a bone end. The brown band across the large end is a crack in the rock, filled with calcite. I've decided to leave it as-is, though with 4-6 hours work I could take it out and glue the two pieces back together.
So here it is in all 4 side views. 

 Here's the end view of the large end - really massive!
 Here's the smaller end.

 Look at this great notch just below the flange on the large end!

Sincerely, Greg Carr

Thursday, July 6, 2017

2 More unknown bones and two well known bones

I just finished 4 more bones and sent them off to Alaska. Last post I presented a very unusual bone that I think is part of a mandible. This time I have two more unknown bones and a quadrate, the link bone between the mandible and the skull. All of these bones were found close to one another. Maybe they are associated?

The bone on the bottom left is another quadrate. We have several of these, all different sizes of course. This one is smaller than the others, and has an extremely thin web of bone between two depressions. The web ended up being held together entirely by glue since it was only about 1/10 of a mm thick!  The bone on the bottom right is a broken illium (pelvis bone) with a piece of rib stuck on the side. Nothing exciting, I've prepared a half-dozen of these. Actually, 7 years ago I would have died and gone to heaven about finding one of these!

The one in the middle is very special. I have a partial one of these from a bigger animal, but neither I nor the guys in Alaska knew what it was. It is long and skinny with a V-shaped cross section. I don't think the bone is more than 2 mm thick anywhere. Most is less than 1 mm thick - very time-consuming to prepare! (about 12 hours AFTER I got it out of the rock). I think it is a parasphenoid. This bone lies in the mid-line of the palate, between the pteregoids, and we haven't found one of these (before now, of course!). The second picture shows it in end-view - you can see how thin it is.

Here is how parasphenoids fit in a skull, looking at the bones of the roof of the mouth. They are found in everything from fish to mammals, so it makes sense they would be in thalattosaurs too. Blue bone is the parasphenoid, ptr is the pteregoid.
Here's one from a modern fish:

Last of all, at the top of the picture is a long, twisted bone. I don't know if it was twisted in life, but judging from the parasphenoid it must have been twisted before burial since it was right next to it and is much more robust. It was not twisted during burial nor afterwards in the rock - the rock has not been distorted like that. 
However, I don't know what it is! It roughly resembles a rib, but it has a triangular cross-section and  a decidedly non-rib thick end. At 7 inches long, it a significant bone - if we only knew what it was!

Anyway, I am still
Gregory Carr

Thursday, June 22, 2017

Once more, into the Unknown

Finding new types of bones is getting very rare. After all, I have excavated over 250 bones by now, and these animals don't have that many types of bones. They do have a lot of bones, but most are ribs, gastralia, centrums and neural arches (backbones to us laypeople). So finding a new type of bone is quite excited and unexpected.

I came up with one such bone a couple of weeks ago. What kind could it be? Let's list out the types of bones we haven't found yet: toes, claws, mandible.....

I think it's part of a mandible. Specifically, the back part, where the mandible pivots on the quadrate. It is definitely broken and the broken end seems to be rounded I was hoping for any break to be a suture, but apparently not this time.

So here is the bone in question. It looks pretty robust in this view. The bulge in the middle might be the pivot point for the quadrate, perhaps.

Here is the opposite side. It is moderately robust, but has a very thin end that curves over in a very interesting way. It is not real evident in this picture, but the inner surface has some very deep grooves of unknown purpose.

And here it is from the side.  You can see how the intact end curves around in a thin bowl-like structure. This would be good for hooking muscles to, I guess.

So here is a drawing of where I think it fits as a mandible. The thin curved end would be where the muscles to open the jaw would attach, and the bulge would be associated with the quadrate pivot point. The front end is broken off. 
And there is still more. There is a quadrate right next to this bone, and a couple of thin bones that are NOT ribs too. Maybe more of the jaw structure? I can certainly hope so. Time will tell.

Speaking of time, I now understand that it will take another year or more until the classification paper is published. I guess this animal is more complicated, more important, and more difficult to classify than we thought! So we must continue to be patient.
Sincerely, Greg Carr

Sunday, May 14, 2017

One Melange, please, with a side of Skull

Things have been really slow this month. I have a piece of matrix that is very loaded with bones and shells. They are so close together that I can't seem to get anything out!

 By my count I have 4 simple centrums, 2 more centrums with attached neural processes, one big gastralia, three ribs (one going right under a nice chambered nautilus), one big 'slipper snail(?)", and a part of a big chambered nautilus. Several more unidentified fragments added into the mix (melange in French). And just uncovered this past Thursday is something that looks like part of the roof of a skull.

Here's a nice centrum + attached neural process, three centrums immediately around it, all touching it!

And here is the skull piece with a proximal end fragment of a rib lying on it and a gastralia alongside it. It doesn't look like much now, but it should be good when I get it out. That's assuming, of course, that it isn't lying on something else. Right now I'm not taking bets either way. There must be an end to this madness!!!

Sincerely, Greg Carr

Sunday, April 16, 2017

Ptergyoid, my Ptergyoid

Ptergyoids are really gnarly bones, part of the skull making up the hard palate, stretching from the front part of the snout back to the brain case. We already had one, found unrecognized and scanned as two separate bones. I probably broke it handling it and thought they were two bones. Luckily Eric Meitz in Alaska recognized that the two bones were actually two parts of the same bone.

So I have just found another one - entire and unbroken. And even better than the last one, all the sharp little teeth in the palate were unbroken. They are very cute, and so small that I decided that I would not completely remove all the matrix around them. Instead, I left some matrix to provide support and revealed just the side. Since these teeth are only a few mm long, they could not have been used to break shells or bones. They would have been just fine to grasp squirming worms, fish or tentacles, however.

This ptergyoid is about 2.5cm (1 inch) larger than the other. Perfectly understandable, given we have so many animals here.

Here is a view of the ventral side (underside) which would have been the under side of the upper hard palate. The front would be on the left, the right extends out to the braincase.

Here are the teeth, enlarged. The ruler markings are millimeters. 

Here is the upper side of the same bone. It sure is gnarly, twisted and beautiful! Check out the slot in the middle - it is very deep, going about 2/3rds of the way through bone. What could possible be the use of this? I certainly don't know.

And check out this beautiful ptergyoid from a mosasaur! Reeeely big teeth!

Sincerely, Greg Carr

Monday, March 13, 2017

Time once again for Girl Scout "Thin...Bones?"

It seems like I have had a run of thin, delicate bones. Perhaps it's just the preservation in this part of the block, or perhaps they were all sorted here hydraulically. I also have a very long gastralia about ready to come out of the same location, almost 8 inches (200mm) long and 3/16" (3-4mm) wide. In any event, I have four bones that have really pushed my expertise in preparing very thin bones.
In the upper left, we have a quadrate. This bone is a link between the mandible (lower jaw) and the skull proper. The jaw articulates on the lower end of the quadrate. Then below it, lower left, is a possible fragment of skull, perhaps back by the quadrate. In the center we have most of the interclavicle (breastbone on humans). Finally, on the right is what I think is a thoracic rib (from the throat area). It has very unusual grooves in it. 

 All four of these have very thin sections, 1-2 mm thick. I have to be very patient and use lots of glue to keep them together. Above is and end-on view of the thinner sections.

 The quadrate is very unusual too. So far I have 3 entire quadrates and 1 or 2 partials. All 3 of the intact bones are very different in proportion from each other. There is a very robust bone (white 3D printed copy below). A second is almost the same proportions but has a much thinner structure, having only about 1/3 of the bone mass in life.  This new one is also different: it is smaller in one direction, but not so in the others. It is like it has been squished flatter. I don't think this is an artifact of preservation - the bone structure does not appear to be crushed. Here they are for comparison in the similar view:

 And here they are showing the significant different direction - only half the thickness.
So I really don't know what's going on - sexual dimorphism? Age differences? 
Anyway, they are soon to go up to Alaska. 
Sincerely, Greg Carr

Tuesday, March 7, 2017

Crocodile in the room

Something has been bugging me for quite a while about these bones - the gastralia in particular. We have two main sizes of gastroliths - some are about 1/8 inch diameter, some are about 1/4 inch diameter. A few are larger and smaller - I have one piece, length unknown (as it's not prepared yet) that appears to be about 3/8 inch diameter - if it's a gastralia. The smallest ones are about 1/16 inch in diameter - thickness of a toothpick. Here is a picture of the longest piece of large gastralia I have found, just uncovered today. The gastralia is the vertical bone across the center. It is about 1/4 inch in diameter (6mm), 165 mm long and had a curvature of 11mm. If we make the assumption that this bone is not too greatly distorted, it may reflect the diameter of the belly of the beast. By standard calculations a chord of a circle with these dimensions will have a diameter of about 630 mm, or almost exactly 2 foot across!  So these bigger beasties start rivaling existing crocodiles, larger than Komodo dragons. Unfortunately I cannot easily find the typical diameter of today's large reptiles, so I can't draw accurate comparisons.
Sincerely, Greg Carr