Tuesday, January 28, 2014

Lots of Nautiloids

One thing we have found a LOT of is Nautiloids. By my count there are currently 8 large and many more small Nautiloids (chambered Nautilus) showing on the surface of this block, and I've already removed three and destroyed a fourth that was on the skull. We have two types - the coiled ones and the straight ones (Orthocones). I really wonder what would cause such a concentration of Nautiloids? My first thought is a feeding frenzy over the dead carcass of the Ichthyosaur. Or maybe a mass die-off after mass spawning? Squids do this, though the current chambered nautilus does not as far as I can tell. Anybody familiar with the habits of Triassic Nautiloids?

I just got done removing the largest and best of them from right next to the skull.
Here's a picture of the side of the Nautiloid with two limb bones in front of it. First I have to remove the two limb bones: they will be in a later post after they are prepared. I can tell they have hollow ends like all the other limb bones.
After I've removed the two limb bones, another nautiloid is revealed. This one appears to be crushed, and only part of it came out initially. I'll try to get more of it out later.

 Here's the really nice Nautiloid, removed and glued back together. The top part came off months ago and we've been saving it safely to put back on.
 Finally, here's the two Nautiloids I removed today. The larger one is complete - the complete shell is there. It's the size of typical souvenir shells sold in shops - 5 inches across. Some of it is really shell, some of what shows is merely the internal mold of the inside of the shell. The shell material seems to want to stick to the external matrix, not the inside fill. Murphy's Law, I guess.
The smaller piece of Nautiloid clearly shows the siphuncle- the internal tube passage from one chamber to the other. Now that the large Nautiloid is out of the way, we can get at the deep part of theback of the skull. From a preliminary look it appears to be split completely front to back down the middle, and we only have one-half. However, this is actually excellent as it will reveal lots of the internal anatomy when prepared. I'll update information about the skull in the next post - major change in our concepts coming! 

Thursday, January 2, 2014

Still more teeth - on a palate or a mandible

This post covers one more bone recovered that contains teeth. This makes a total of 4 bones with teeth - a jaw fragment with teeth in sockets, a skull, a jaw fragment with a trench where teeth were, and now a long convoluted bone with small teeth in the center.
Originally I thought the bone might be a clavicle of the Ichthyosaur, since we have most of the other shoulder girdle bones. The first side exposed had no indication of the teeth - they were on the rock side (inside) of the bone.

However, the first sign of teeth occurred as we were cutting around the backside of the bone to free it from the rock. We cut it quite deeply so as to not damage anything, since we didn't know what we had. Since the bone was long and thin, the side without rock was coated with latex and mounted in plaster. This provides enough support that even thin and fragile bones can be successfully prepared without breaking them to bits.
Here's the front side after complete removal from the large block and preparation:

 And here's the back side, showing the teeth. 
Here is is zoomed in to the teeth area which is about  4.5 x 1 cm. It probably continued to the right, but the bone is now broken. These teeth sure are cute, but were a real problem to prepare. Most of the teeth crowns are intact, though I did lose one or two of the very small ones during the preparation process. Note that these teeth crowns were broken in life. I don't know if they were mandible teeth, which would have been from the left side, or it they are palate teeth (amphibians have & had teeth sticking down from the hard palate). They look like they are in sockets, multiple rows, so I'm guessing they are from an amphibian and not the Ichthyosaur. But they sure are a different scale - much smaller - from the socketed teeth already prepared.

For your reference I've included pictures of the other jaws and teeth that we have found so far. They are much larger than the teeth on the featured bone above - the teeth in both pictures below are really about the same size.   

 Until next time, this is Greg Carr from OMSI Paleo lab. I hope your holidays were happy and blessed.