Unlike the left lower jaw, the right lower jaw is composed of just the middle section and is missing both ends. The scabby appearance seen on the right portion of the lower jaw is due to rock, plaster, and glue that still covers this section. The rock was left on the bone and plaster and glue were added to try and stabilize the jaw during the initial preparation. This initial preparation of the right lower jaw occurred before it came to the Carnegie Museum. A more thorough cleaning will make the lower jaw look considerably better.
After preparing the premaxillae or the very front of Samson's snout, I decided to try and find the teeth that would have been located within the open sockets and prepare them. Studying the teeth that were collected around Samson's skull (more than 20 teeth), I was able to identify the five teeth that fell out of Samson's snout (see previous entries) or the element from the very front of Samson's skull before it was buried. The teeth found at the very front of the skull differ from the teeth found along the sides. The easiest way to see these differences is by looking at the shape of the teeth and the location of the serrations on the teeth. Similar to steak knives, Tyrannosaurus had serrations or denticles on its teeth that helped it cut through flesh. Teeth located at the front of the skull are flattened from side to side and have serrations that are found along these sides. Whereas teeth along the sides of the skull are more round (like a banana) and have serrations along the front and back. In the image below the tooth at the top is from the front of the skull and the tooth at the bottom is from the side.
A tooth from the front of skull with the serrations on
the side (top) and a tooth from side of skull with the serrations
on the front and back (bottom)
A tooth from the front of skull seen from the back with
serrations along either side.
After a fair amount of preparation the premaxillae (tip of Samson's snout) begins to reveal the openings where the teeth were located. Each side had 4 openings as seen in the images below. Compare these images from the previous entry to see what Samson's premaxillae (snout) looked like before and after preparation.
Prepared snout (premaxillae)
Openings along the bottom of the snout (premaxillae)
for the teeth
Most of the preparation has already been done on the snout of Samson except where the individual teeth would have been located. The openings are still filled with rock (light tan in color) and will need to be prepared out. Can you guess how many tooth openings there were in this element? As it turns out, there were 4 teeth in each side so a total of 8 tooth openings should show up as I prepare it. On the right side, you can see 3 teeth with the one on the far right side broken off.
Image of Samson's snout or premaxillae-view from the
bottom.
Time for another jacket. I expected from the shape of the jacket that I would have the opposite hyoid (throat bone), and lo and behold, it was. The ends on this one are in slightly better shape, though still broken. There are, however, some sections with a hard matrix stuck tightly to the bone. I don't really want to use an airscribe on this piece because it is fragile, so it will require hours of scraping by hand. But that's okay. I like this type of work. I find it calming.
I placed the hyoids side by side in these pictures. The new one still has some matrix stuck to it, showing only on the "dirtier" side.
In your inspection of Samson, you have probably noticed that the very front of Samson's skull or his snout is missing. This part of the skull, known as the premaxillae, was found near the skull during the collection of Samson in the field. It was probably separated from the rest of the skull after death but before the skeleton and skull were buried by mud and sand.
Snout (premaxillae) of Samson seen from the front-Notice
the teeth protruding from the bottom of this element.
Snout (premaxillae) of Samson seen from the top
Removed pillar on the left and another pillar that still needs
to be removed on the right.
Pillars at bottom of jacket being removed.
Samson is finally to the point where he will have to be rotated into a position to prepare more of his skull. The plan that we have come up with requires Norm and I to remove a lot of the plaster pillars (seen at the bottom where the skull jacket meets the wooden base in the pic) holding the skull jacket in place so that we can attempt to rotate the skull. We have managed to remove one of the pillars (as seen in the close-up pic) and are now working on removing others. We will replace these plaster pillars with wooden blocks that we can easily remove when we need to. Hopefully this part of the project will not take that long but who knows.
Here
is a close-up of the tooth.
The the tooth shows wear patterns along its surface telling
us that it was used even after it was broken.
Here is Samson's left lower jaw. I am proceeding to clean the entire surface and teeth along with the tooth openings. One tooth towards the front of the jaw is peculiar because it was broken off and then Samson continued to use it.
The "unidentified skull element" is the left jugal. What do you know about that? This is good because we thought it had broken off from the left jaw joint area. It did, but it was not lost, and we can put it back where it belongs.
I am pleased by the quality of the bone. It is crisp -- that is, the surface cleans nicely, but it is brittle. We will probably have to use air abrasives to clean out the tiny nooks and crannies. The technique is similar to sand blasting, but in this case we would use baking soda instead of sand.
Take a peek at this weirdly shaped bone:
Once the jacket has been opened, the separator, tin foil in this case, is seen. The separator keeps the plaster from sticking to the bone.
The tin foil is removed to show the left lower jaw and several teeth.
Here
is the lower jaw still wrapped in a plaster and burlap jacket.
The location of the teeth within the jacket are shown in light
blue and black marker on the jacket. You should notice that
this block is not as long as the skull. Typically the lower
jaws are as long as the skull because the lower jaws articulate
at the very back of the skull. In this case, the lower jaw
in the jacket is not complete and we hope to find more of
the lower jaw in another jacket to make it complete. We will
see what is missing as I open the jacket up.
Over the weekend Norm and I applied a silicon rubber (seen as white to clear) called Dragon Skin to the back of the skull. Because the rock is so hard and the bone is fairly thin we decided to use a silicon rubber to reduce the amount of vibration and hold the back of the skull together. The nice thing about silicon rubber is its ability to easily peel off once it sets up. So once we are done with it we will peel it off and the skull will be unaffected.
The
dark spot at the bottom of the image is the occipital condyle,
the ball at the back of the skull that connects it to the
vertebrae. I will continue to expose this area a little bit
more over the next couple of days.
June 17, 2004 10:39 AM
The
above image is of a block that was associated with Samson's
skull in the field. It contains a skull element that was disarticulated
from Samson's skull after death and sometime before final burial.
There are a number of skull element jackets that belong to Samson's
skull that will need to be prepared along with the skull. I
will be opening these jackets over the next several weeks to
months in order to determine how complete Samson's skull really
is.
I opened a jacket from the box of "accessories" that came with Samson. It is considered an "unidentified skull element", so labeled by the folks who collected the skull. Well, I can't identify it either, not yet anyway. It's about the size of a dinner plate.
I had to open it with the cast cutter (like the physician's tool). Then I had to carefully scrape off some plaster that caused the bone to remain stuck in the jacket. Finally freed from the jacket, the bone needs little preparation. The bone material itself, however, is brittle. It has some breaks that need to be glued, and it needs a detailed cleaning.
Then perhaps I can figure out what I am working on! Seems sort of backwards from the way it's supposed to go...
Here is an image of the top back portion of Samson's skull. The yellow line separates the bone (redish-brown) from the very hard rock (grey). I have been removing the very hard rock out of the right opening for several days now. The position of the hard rock makes removal difficult and awkward. These openings (left and right) continue through to the bottom of the skull. If this hard rock continues to the bottom of the skull, preparation of this opening may take weeks. I am not looking forward to that. I will continue to remove more of this hard rock to try and determine the extent of it.
Yesterday and today I have been working on the right side of the skull. The entire skull is visible on the left side but on the right side only the upper portion is exposed. To get a better idea of the total extent of the skull on the right side, I have been removing parts of the plaster jacket. It is a very time consuming process because the plaster jacket is so thick (measuring in some places over an inch and a half). As I have removed these sections, I have continually applied a consolidant to the exposed bone so that it will harden and remain intact. Several days may be required to remove the plaster and burlap along the lower right side while protecting any newly exposed bone.
We have recently moved a large crate up into the lab which contains other skull elements that were found around the skull while it was being collected in the field. Each of these skull elements is wrapped in its own plaster jacket for shipping and await preparation. You have probably noticed how the very front of Samson's skull is missing. This skull element is one of many that are waiting to be prepared and reinserted into its location on the skull.
For the last week I have been removing very hard rock from the right supratemporal fenestra (opening on the right side at the top and back portion of the skull) using a airscribe (minature jackhammer). The rock is very resistant in this area along with the right eye socket. All the other rock seen on this specimen is quite soft and easily removed with dental tools. Removing the very hard rock is a slow and tedious process because vibration from the airscribe could break large pieces off the skull if it is not removed slowly. Once the majority of this hard rock is removed, I will expose more of the skull on the right side along the tooth row.
What a spectacular Tyrannosaurus skull! I recently began work on Samson and for the last couple of weeks I have been brainstorming in an effort to set up a plan by which to prepare this magnificent specimen. In some ways it is a difficult specimen to work with because of the hardness of the rock in certain cavities of the skull. So the initial plan is to remove or determine the extent of this hard material and remove it. Secondly, I want to remove more of the plaster jacket on the right side so that I can see the extent of the skull and teeth. Finally, we will put a protective cap on the top and turn Samson over so that preparation of the palate (roof of the mouth) and teeth can be facilitated. That is the current plan but with all plans it may change a bit as we see the need.
I spent today removing the concretion from top of the skull. It was difficult because the air pressure was low and my airscribe kept stalling. I did manage to remove quite a bit of rock though.
Today one of our volunteers, Carol Hammer, continued preparation of Samson. She mostly worked on the back end of the skull, using a pin vice, plastic spoon, and a brush to carefully remove the soft sand. The biggest problem that she encountered was that her back got tired from sitting in a twisted position. She occasionally worked on the sides of the skull to give her back a break. Working on Samson gave her hand a much-needed rest from her usual project- removing very hard rock with a pin vice from a vertebra (backbone) of the pelycosaur reptile, Dimetrodon, spine.
Today I worked on the back of Samson's skull. There is a very hard concretion here that we are using an airscribe on.
Today was my first attempt at preparing Samson. I started off by removing the soft matrix from the back end of the skull. The rock was so soft that I could almost use a plastic spoon to scape it off. I got bored with this so then I worked on removing some very hard rock on the top of the skull. I tried three different airscribes and found that the first one that I used, the Aero airscribe, worked the best.
The Science Behind Samson
The Samson skull is the best-preserved Tyrannosaurus rex skull ever found.
This new fossil adds to a growing number of relatively complete Tyrannosaurus rex skull specimens. A large sample of skulls enables scientists to study the dinosaur's structure and growth patterns. Data collected from the skull is also crucial to understanding evolutionary relationships among the tyrannosaurids, as well as other theropod dinosaurs.
Previous research on Tyrannosaurus rex skulls reveals its small brain had very large olfactory bulbs for smelling, which means it had a keen sense of smell. Once the skull of Samson has been prepared in PaleoLab, we will be able to learn more about the internal structure of T. rex.
More Samson Logs: Winter 2005/6 | Fall 2005 | Summer 2005 | Spring 2005 | Fall 2004
