Sometimes, life is the Pits

I've been working on a great piece of the upper jaw of our Thalattosaurs. I just got it finished today - still have to scan it before it goes to Alaska.  It has two wonderful new things to teach us that I haven't understood before. Here is the inside (lingual) side of the jaw.

And here is the outside   (Bucal). It is 14.8cm long (almost 6 inches). 

The first item is that this upper jaw, containing part of the hard palate, has a large vomeronasal pit. This pit is located at the outside edge of the palate where it hooks to the tooth row. These pits are smelling organs used in conjunction with the animal's tongue. Think of a snake or a monitor lizard - they put out their tongue, wave it around a bit, then retract it. Out in the air the surface of the tongue absorbs molecules that we refer to as 'odors'. Upon retraction the tongue tip is inserted into the vomeronasal pit, where the molecules come off the tongue and attache to smell sensor cells on the walls of the pit. In this way some reptiles have an accurate sense of smell.

 Why is this important? - because these pits have not been identified in this type of animal before! Preservation of other hard palates hasn't been good enough to see them clearly. This pit is quite deep, over 1 cm and almost pierces through the top of the palate. The bone at the top is less than 1 mm thick. I think this has major implications for the lifestyle of these animals. Smelling your food in the water, perhaps, along with excellent vision to hunt them down in deep water?

The second 'Pits' in this essay are concerning the teeth. There are 6 major teeth in this jaw.  All of these teeth have been broken off at the bone line. They all show extensive abscesses through the dentine down into the jawbone! This can tell us much about the teeth of these animals - they are very different than lizard or dinosaur teeth and much more like mammal teeth.

Here is the biggest tooth - it is about 9mm across. The most prominent ring is the hard enamel, which is the hardest part of the tooth. The enamel is broken exposing the dentine inside the tooth, where mammals have their blood vessels and nerves. This is what is removed by the dentist when you get a 'root canal'!

 This did not happen at death - if the tooth was broken at death, the dentine would still be filling the inside of the tooth and it would be relatively flat-topped. Instead, we have a pit where the dentine rotted away before death.

Here are two other teeth. As before, there are very deep pits on the inside of the tooth inside the ring of enamel. One of these pite is only about 2mm diameter but over 8mm deep! And there is still matrix at the bottom - I can't see to prep it out deeper.

 Here is the most severe pit of all. You see the two rings of abscessed teeth  - in between there is a hole where half the tooth enamel is still present, but the entire other half of the tooth and the surrounding bone is missing.

 This side view shows how much bone is missing - the hole is about 12mm long, 6mm wide and about 8mm deep. This animal was probably hurting!

Older dental abscesses are known, including one from a Permian animal. http://blog.everythingdinosaur.co.uk/blog/_archives/2011/04/20/4799483.html  The authors of that paper concluded that these were true real-life dental problems and that their animal did not frequently shed it's teeth. Dental abscesses are unheard of in modern lizards, and not very common among dinosaurs since diseased teeth are merely shed and not allowed to decay. Perhaps Bernie's type of animals did not shed their teeth either? 

Sometimes life is the Pits. 

Sincerely, Greg Carr

One Mystery solved - it's a jaw fragment!

I've been working on a small block that is check-full of bones. We started uncovering a skull fragment last week, and I thought it was part of the top center of the skull, along the midline of the pineal gland. This afternoon took it off the block.

Now that I've got it off it is clear that it is something else - it's about 2/3rds of an upper jaw, left side! There are lots of teeth, or at least teeth roots, and the lower part of the nasal passage and the hard palate. The hard palate has a different shape that the one in the original skull which is apparently broken. This one is more intact.

I'll have to wait until I get back to OMSI ( I'm sick this week) to finish the teeth with a Paleotools #2 - my modified Chicago Pneumatic air scribe is just too damaging for the teeth. I learned long ago that the teeth are so fragile that only the most delicate tools can be used.

This fragment of jaw may be from the other half of the semi-skull we already have, or may be from a different one. We'll have to take some accurate measurements to tell.

Anyway, it's great to get more teeth. It has been about 2 years since we found a fragment with teeth and/or teeth roots.
Sincerely, Greg Carr

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. 

Back in the Saddle Again - Recreating a full skeleton

I've taken off several months from writing the Blog since I had a lot of things to do this spring - doing taxes for H&R Block, refurbishing a rental house, letting my right hand rest from air-scribe work, etc. But I'm back and proceeding at full speed ahead! (to mix metaphors)

I've been working at recreating a full size skeleton of a Thalattosaur. As readers of this blog know these bones are scanned before being sent off to Alaska for study. I can scale them in X,Y or Z dimensions using the 3D printing software. I have now printed out a full set of backbones based on a well-preserved Centrum+Neural Arch  specimen from Bernie. I scaled them and numbered them based on a well-preserved Miodentosaurus Brevis skeleton from China. I then added some 1/4 inch (6mm) foam pads to mimic the disks between the vertebrae. The resultant skeleton is about 13 feet (390cm) long. I'm not too worried about the exact length - we have bones of animals from 2 feet to 30 feet (0.6 to 9 meters) so any animal in that length range would be representative of a proper Thalattosaur. There are some significant challenges to printing out a 30 ft skeleton, however!

Next most common bones are Ribs. I made up a full rib in cedar wood, again based on the Miodentosaurus, since all the ribs recovered here are broken. I then made a silicone mold and cast about 52 copies! Boy, that sure is a lot. These copies will be shortened to match the Mio... bones and then mated up to the appropriate body vertebrae. I have chosen to hook the ribs to the centrums with small supermagnets. That way the ribs are removable for transport or storage.



The centrums themselves are strung on steel rods passing through holes where the spinal cord ran in the original bone.The rods are slightly less than 4 feet (102cm)  long so they will fit in a 'standard' display cabinet. This way the skeleton can 'swim' through 4 sequential cabinets at rock shows. It also makes it much easier to transport.

After the ribs I'll be working on tail chevrons and limbs. I will be attending a  National Federation of Rock Club show in late July, and Eric Meitz will be presenting at the SVP (Society of Vertebrate Paleontology) in October. I hope to have the skeleton, in whatever state it is, displayed at these shows.

I'm also preparing still more bones from the original matrix blocks. One of the original large blocks 200+ pounds (100+ Kg) is yielding another nice limb bone. I'm also working on a smaller block at home where I have a nice boom microscope. In a block about 10 inches (25cm) I have at least 8 centrums, two neural arches, two rib sections, and a very nice skull fragment at least 5 inches (12cm) long! And I have yet to expose all the bones in it! That will be for the next post (soon) I promise.
Sincerely, Greg Carr

Newest 'Unknown' bone identified - and does it have a story to tell!

The saga of Bernie the Thalattosaurs has now taken yet another twist of the tale. Or should I say Twist of the Tail?

My last post was about a new bone that has just been excavated. I thought it was a bone that hadn't been seen before, hoping that it may be an elusive mandible or the missing inter-clavicle. The bad news is that it isn't a new bone - we have seen them before. The GOOD news is that this bone opens up a whole new world of wonder to contemplate.

The new bone is a chevron - one of the tail bones making up the spinal column of the tail. Together, the neural arch, centrum and chevron shape the tail into a vertically flattened oval, perfect for swimming. Chevrons are common in reptiles, and are even found in some mammals like whales, porpoises and manatees. We have already found several of them. In thalattosaurs they are a delicate Y-shaped bone generally 5-8 cm long in these animals such as Bernie or Miodontosaur Brevis.
Here is a picture of a Mosasaur tail, clearly showing the neural arches, centrums and chevrons (from top to bottom). This particular animal was about 6 Meters (20 feet). long. This one suffered injury during life that let to bone pathology. Picture courtesy of "Oceans of Kansas". Note that the chevron in the middle is about 7 cm from the tip to the notch - there will be a test later.

This is a picture of a copy of the most complete chevron found to-date from Bernie - it is about 5.5 cm long, a little over 2 inches. From the notch to the tip it is about 3.5 cm.

OK, so what is so unusual about this new bone that you didn't immediately recognize it? These chevrons are quite distinct. In one word, the difference is HUGE!!!

This new chevron is 11 cm from the tip to notch!

This is three times larger than the other centrums we have found. Scaling from the very complete Miodontosaurus Brevis from China, this would be an animal 10 meters long (33 feet). Scaling from the mosasaur above (remember the 7 cm chevron?) this would also be an animal about 10 meters long. In other words, a real GIANT!!!

Here is a picture of the actual bone, a copy of the normal -sized chevron, and the chevron enlarged 3.0 x to match the new centrum. [Aside, this is one of the benefits of 3D printers - I love 'em]. The match is pretty good all things considered. 

Bernie is already among the largest thalattosaurs ever found, and the largest found to-date in North America. This new chevron, pushing the size of these animals to 10 meters or so, is mind-boggling.

There is the possibility that this bone is not from a Thalattosaur, although the slanted tip and grooved body are found on both bones. We will hold judgement on this until later. For now, just consider a 10m (33 foot) mama Thalattosaur looking over a whole colony of young animals only 1-3 meters long!

Sincerely, Greg Carr

Yet another new type of bone!

Things are progressing on the preparation end of things. I have removed and finished another limb bone, one we've seen before. probably one of the lower limb bones - like the tibia/fibia. This post is about another new bone, one not seen before!

Parts of it appeared during the latest limb bone extraction. The matrix around that limb bone was particularly nasty, consisting mostly of chert course sand in the limestone matrix. This type really gives me fits since it breaks and dulls the point of the air scribe very quickly. I have to sharpen the bit several times an hour in this stuff. However, the good old-fashioned hammer and chisel remove a lot of this material and I applied my 3 pound hammer and cold chisel liberally.

One big chip took off a flake the size of my palm about 1/2 inch thick (1 cm) and revealed the end to what I assumed was two ribs lying side-by-side. After I removed the limb bone I decided to work a bit on these two 'ribs'. However, after only a few minutes work it became apparent that these were the same bone, with two branches (bifurcation) that had been exposed. It is about 5 inches long, and I don't know how much is still hidden.

Another day's work revealed that this was a substantial bone - but what is it? Here is a picture of one of my better reference skeletons - Midontosaurus Brevis from China. Can you see a bone that looks like this new one? Two candidates come to mind - the interclavical or the lower jaw. However, neither one is a close fit. So we are left with the question - what is it?

I'm actively pursuing this and will be working on it tomorrow and Friday.

Sincerely, Greg Carr

Tail and WTF Bone - Redux!

This is an update on two parts of the project: Re-creating the tail of a Thalattosaur and preparing a very strange bone.

The tail is mostly finished - all the centrums+neural arches are printed and fastened to a mounting base. The 65 tailbones add up to just about 6 feet long (180 cm to those of you in the logical world). I am still missing the chevrons that go underneath the centrums, but I haven't printed any of them yet. It was an interesting exercise in modeling, printing with both 0.5 and 0.3mm nozzles, temperatures, etc. I ended up printing the 45 largest bones with a 0.5mm nozzle and 0.2mm layer thickness. The smallest 20 had to be done with the 0.3mm diameter nozzle at 0.1mm layer thickness to maintain sufficient resolution. The largest bone took about 4 hours to print: the smallest about 7 minutes! I really like how the tail gets blunt out toward the end, like a crocodile, rather than very thin like an iguana.

As for the very strange bone, it is almost finished - and I STILL DON"T KNOW what it is!

It looks like a limb bone. It doesn't look like any of the other thalattosaur limb bones. The bone is very convoluted, with a very prominent ridge down the side and two very deep hollows. The ends of the bones - the articulating surfaces - are different as well. Whereas the Thalattosaur limb bone ends are concave with conical depressions for the cartilage, this bone has rounded ends with only a hint of hollowness. I really suspect that is a humerus of a very different type of animal. Perhaps it's from one of the ancient marine amphibians that were still alive then, or a crocodile or turtle ancestor! Maybe Pat and Eric at the University of Alaska Fairbanks can figure it out

This shows how deep the hollow in the side is. My fingertip is sitting in it - about 3/4 inch (1.8cm) deep!

Anyway, If I don't write again before the Holidays have a great time!

Sincerely, Greg Carr