Tuesday, January 19, 2016

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

Tuesday, January 12, 2016

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