A Robust Bone

Even with having to pack up the paleo lab’s contents in the old building, and move, upack, and reorganize them in the brand new lab in the new BLM building, some great progress has been made on Basilemys.

The team decided to completely excavate each element inside his shell rather than leave them in place and be satisfied showing off the bones they had already partially exposed.  This allows them to explore the entire inside of the shell to find more bones, if there are any, and assure themselves they haven’t missed something good.  Removing all bones may actually provide the opportunity to learn more about Basilemys.

Here is a picture of our favorite tortoise taken a while back, before he was flipped over.  The blue outline indicates shell, the red may be a vertebra, the yellow is part of the coracoid (bone forming a joint between the shoulder blade and sternum), and the green is the elbow end of the humerus.

 

 

 

Flipping the tortoise allowed the team to positively identify some of these bones and, in some cases, see the entire bone structure. The humerus and small section of shell to the right of it were prepared, revealing what is shown in the photo on the right.  Outlined in blue is the shell, green shows the two ends of the humerus, purple is the shoulder blade, and yellow and orange are parts of the coracoid.

Removing the section of shell covering the rest of the humerus allowed the entire bone (outlined in green in the photo below) to be exposed.

 

 

 

 

 

 

By the end of the day the entire humerus was able to be lifted out. Left behind, for now (photo on right), are the shoulder blade (purple) and exposed coracoid (yellow).  The area in the circle shows where the first end of the humerus was exposed when Jim originally started working on it.

 

 

And here is the humerus in all its glory!

 

 

 

The first four photos, starting from the left, show all sides of the humerus with the shoulder socket on top and the elbow joint on bottom.  In the rightmost photo, on top is a view of the shoulder joint head on; on the bottom is a head-on view of the elbow joint.

You can see how robust the humerus was.  Its size and thickness mean it was definitely designed to bear weight.  Paleo lab manager Tylor commented, “If you handed just this bone to me, I would think it was not a turtle bone.”

Jim has started to prepare out the shoulder blade and the coracoid.  Right behind the coracoid is what is thought to be a vertebra.  Stay tuned to see what surprises Jim may uncover in the coming weeks.

What IS That Weird Flat Bone?

That’s the question Jim and Tylor were asking one another over the holidays.  And with the new year came the answer.

But let’s back up just a bit.  In late December, Balisemys was flipped over, the rock covering his shell was peeled away, and the weird, flat bone made its appearance in an area where the shell was missing.

Jim and Tylor went to work on it and were finally able to identify it – it was Basilemys’ left shoulder blade.

 

 

Look at the size of it!

 

The bone off to the side of the shoulder blade (circled in red in the photo below) is the coracoid (circled in green) which makes up the rest of the pectoral girdle (shoulder socket).  The area circled in blue is shell.

Tylor said of his and Jim’s handiwork, “We were amazed by the size of these bones inside the shell. If we were to find this bone in the field with nothing around it, our first assumption would be that this is a dinosaur bone not a tortoise bone.”

Since Jim outlined a good bit of the shoulder complex, he began to cut off some the excess rock on the side of the tortoise and lo and behold, there was another bone.  Given that it is near the shoulder blade on the bottom and a limb bone on the other side, it may be another part of the arm or leg (circled in red).  Jim will continue removing rock from the inside of Basilemys to find out.

A Look Back — Way Back!

On Tuesday, January 10, 2012, in Page, Arizona, Dr. Alan Titus, GSENM paleontologist, will talk about two new predatory dinosaur species named in 2011 from the Monument: the giant Teratophoneus curriei and the much smaller Talso sampsoni.   These two new animals have no direct ties to any species known from north of Utah, and are instead related to forms found in New Mexico.  Dr. Titus will explain how this single fact reshapes our view of North America as it was 75 million years ago.  His presentation, which starts at 7 p.m Mountain Standard Time,  is part of the 2012 free Glen Canyon Lecture Series being held at the Carl Hayden Visitor Center at Glen Canyon Dam.  To see a calendar of planned lectures and descriptions of each one, go the the Glen Canyon Natural History Association web site.

Basilemys Gets Plastered . . . Again

We haven’t posted for a while, but that doesn’t mean the work on our ancient tortoise has come to a standstill. For more than a month, Jim and Tylor have been piecing fragments of shell together and stabilizing the entire shell with glue in preparation for turning the big guy over.

Jim covered the shell with wet paper towels and then draped it with strips of burlap soaked in plaster, the same thing that was done to prepare Basilemys for his trip from the field to the lab many moons ago. The current plaster jacket is covering the exposed areas of shell and keeping everything intact while  Balisemys rests on his back for a while.

 

 

Once the tortoise was flipped, the rock began to separate itself from the shell and peeled off in one big section, revealing what was preserved on the bottom.  As you can see in the photo on the right (click on the image to enlarge it), there is a beautiful section of shell which is so well preserved that you can see the sutures between the plates and the pitted decoration.  The bottom shell is not as complete as the top, but that’s okay because it allows easier access to the bones lying between the top and bottom shells.

You might remember from previous installments that we have lots of unidentified bones that need further preparation, and you never know what new bones will be found. In the photo below, there is a smooth flat bone that still needs to be identified.  Any guesses?  If so, click on “Contact Us” under the About Us tab and let us know what you think.

 

 

We’ll be back when we have more to report.  Meanwhile, happy holidays to all!

 

Crime Show or Chess Game?

The plot thickens.  Take a look at this pile of bones.  (The view is from the front of the tortoise, looking down on it.) How does one make sense of it all?  Well, the bone outlined in green is either a humerus or a femur. (Bones may have shifted around a bit 75,000 years ago when Basilemys was unceremoniously  moved into his rock abode.) The bones outlined in purple are unidentified ones from previous weeks.  Blue outlines show pieces of shell.

This week as Jim started moving into the shell to work on a previously uncovered bone (the one circled in red, which is also not yet positively identified), he found two new bones below it. The bone peeking out (circled in yellow) from under the old mystery bone is one of the two new mystery bones.  The photo below shows them both circled in yellow.

 

This is still the front of the tortoise, but looking inside of it instead of over it.  Once again, the area outlined in blue is the shell.

Preparation is going to get more difficult with all these new bones inside of our tortoise.  To safely prepare an element, you must remove all the rock around it.  But when you have bones stacked on top of one another like we do with our tortoise, this can get a bit tricky. How can an element that’s attached to another element be prepared and gotten out of the way without damaging either one?

Next week the paleo team is going to spend time figuring out the answer to that question.  They will determine the order in which to remove the elements and figure out how to support the remaining ones after each piece is removed.

We hope to be back next week – depends on how long it takes to formulate the plan of attack.