Sunday, November 11, 2007

Day 7: 10 OMGs

Dr. Bakker has an impulsive, informal response to most paleontological finds. If you've got something cool - like a tooth in perfect condition, he'll exclaim, "Oh my God, look at this." If it's really cool - like a razor-sharp claw he's never seem before, it's "Oh my God, Oh my God, what is this?" And so on - the cooler the find, the more "Oh my God"s you get. So, the team has taken to rating it's finds in OMGs (or, "Oh My God"s).

Before today was out, we had a 10 OMG discovery. But first...

This morning, Dr. Bakker was greeted by a very different dig site than the one he left on Wednesday - it was the first time he's seen many of the big finds of the week, including the very large Dimetrodon humerus that came out yesterday. (He left to be honored mid-week by his home state. As many on the team were surprised to discover, even though Dr. Bakker looks like a cowboy, he actually hails from New Jersey.) The site's namesake, Amy, also returned to work on her find.

Dr. Bakker examines the newly-uncovered humerus while site namesake and discoverer Amy Taylor starts working on the far North end of her site this morning.

UPDATE: in this video, Kathleen talks to Amy about her discovery of a site that's turning out most of a Dimetrodon - the biggest pre-dinosaur predator.

Since the central objective of the Amy site is to get the entire hill down to the lower level that holds the associated Dimetrodon skeleton (while preserving and mapping all the bones in the middle layers), the first order of business was to map, document and remove the humerus in order to continue digging downward.

Chris maps and removes the Dimetrodon humerus. Dr. Bakker decided that it should be removed right away to make way for further digging.

Within minutes of the humerus' removal, Kim found the clavicle. In perfect condition!

Kim and Johnny work on excavating under the level where the humerus was found. Little did they know that they were about to uncover another significant fossil.

Here, the clavicle Kim uncovered is outlined in yellow. It is in extremely good condition - it's complete, with nothing at all missing.

At this point, everyone is pretty happy with the day's work - a major site keeps producing more fossils of the same animal, plus a major new bone. So, they're working along, when all of the sudden...

"Oh, my God. I've got the jaw." Chris starts to uncover his new find, about 5 inches over from the location of the humerus and clavicle. It gets that plus 9 more OMGs from Dr. Bakker.

A tooth. In place. In the jaw. What looks like possibly the ENTIRE upper jaw.

Here, you can see the first tooth that popped out of the ground. The mound of earth in front of it contains the jawbone.

At the time this image was taken, 5 teeth had been excavated - three more (indicated by the dotted blue lines) would be revealed before the end of the day. This looks to be almost the entire upper jaw.

With eight full teeth. It's a major find. A 10 OMG, for sure. And - it's in such good shape, they're expecting to find the rest - possibly with the front "killing teeth," tomorrow. In addition, the rib cage is surprisingly intact, the spines are very long and the jaw is amazing - all 8 teeth that remain attached are in pristine condition. Dr. Bakker believes these fossils will need very little prep work before they are ready for display.

According to Dr. Bakker, "That solves the mystery!" This jaw proves that the skeleton we've been working on is, in fact, our mystery animal - so far represented by four small teeth from the Aimee site and a giant fang from the K2 site. It's a Dimetrodon for sure, but we don't know what the species is yet. If this is a Dimetrodon loomisi, Bakker says this find could possibly be the best preserved specimen to date. And it is in spectacular condition.

More photos from today:

Piece of cake! Johnny, Chris and Neal pull the second jacket out of the Spine site. The first jacket, taken out yesterday, was about twice this size.

It might have been smaller - but it was still more than 200 pounds, way too heavy and unweildy to carry up the steep slope to the trucks.

Man of the Hour: Our friendly, neighborhood front-end loader driver, Gary Coltharp - who was kind enough to donate his time and equipment to the cause, and help us get two very heavy jackets out of a very inaccessible site.

Johnny and Kathy excavate the Amy site today.

Dr. Bakker surveys the entire site at the end of today's dig. By half of the hill is gone. Foil covers the jaw discovered today, as well as several fossils that have been mapped and removed from the layer. It's amazing to compare this with the site a week ago.

Neal Immega - What's this rock doing with red and green spots?

This is a fine grained quartz sandstone from a shallow creek that flowed during Permian times at what is now the Craddock Ranch. Notice that the rock is made up of layers that dip to the right. These are called forsets and are the leading edge of a ripple in the sand at the bottom of the creek. Moving water transports sand in the shape of a ripple. If you look closely, you will see that there are several of these angled layers and each layer truncates the previous one because the moving ripples tend to erode some or all of the previous one.

The red and green color comes from iron in different oxidization states. If you could examine the grains with an electron microscope, you would see that the quartz is coated with a layer of iron-rich clay. I think that the original color of the rock was red like all the other sediments in these redbeds. Rivers also transport organic material, like plant debris, along with the sand. Bacterial decomposition of the organic materials will also reduce the iron, changing the color of the iron from red to green. The green spots come from decomposition of isolated bits of organic material.