Sunday, July 8, 2012

Revueltosaurus Quarry- The Evolution of A Jacket

In field paleontology, one of the most important things you do once you find bone is create a proper field jacket. Jeff Martz recently created a nice little cartoon that describes the typical steps involved in jacketing bone once it's found (above), although he does leave out a very important final step - carrying the jacket out of the field. Here I'll show you what these steps look like in real life - an example from the Revueltosaurus Quarry - as we go from finding bone to bringing it home.

Step 1 was complete in 2004, when Bill Parker and his interns discovered this site while prospecting. In anticipation of finding more bone, we've been excavating (Step 2) since the beginning of the summer. A little over two weeks ago (June 22nd, 2012), we removed the first two big jackets from the Revueltosaurus Quarry here at PEFO. One weighed around 100 lbs, the other over 300 lbs. The 300 lb jacket contained what is likely an entire individual revueltosaur.

Slowly outlining where the bone is. It's hard to see, but the bone is a faint orange color in the middle of the photo.
We first encountered bone in the general area on June 2nd when Frankee Sena pulled out a big chunk of overburden with bone on it. Since it came from a hole, we all had to start bringing things down to that level in the surrounding area.  I found a few isolated vertebrae, but then on June 4th, we found the jackpot. The bone just wouldn't stop. This is the point when, even though we just spent days (if not weeks) hoping to find bones, we started cursing each new bone that we found. It's starts to get overwhelming. And in the back of our minds, as we watched the area of bone expand, we were all thinking "this is going to be a really heavy jacket".
Jacketing some parts of the block as Bill continues to define the edges.
We managed to define a few edges (Step 3) before the end of the day, so I started to jacket (Step 4) part of the block. It's important to protect the bone as best you can when excavating, so if you can start to jacket something, you should. First I put down a separator (toilet paper) then started adding plaster (small plaster medical bandages).

The block continued to expand, until we were finally able to define all the edges (Step 3) by June 12. By June 15, we had a complete, jacketed block. We also had the second block starting to take shape right beside it. Bill managed to recruit some help to haul these two jackets out of the quarry and up out of the badlands, so by June 21, we were ready to flip them both (Step 5). A testament to good jacketing, both blocks flipped perfectly, with no signs flexing.

With the smaller jacket flipped, Bruce chisels out some excess rock.
After flipping them, we cleaned some rock off the bottom (to lighten the jacket a bit) and plastered the underside. And on Friday, June 22, the Youth Conservation Corp (YCC) kids arrived to help us carry them out. This post is dedicated to them (and the two park rangers, Lauren and Desmond, who were in charge of wrangling all those teenagers). It took about 2 hours to carry those jackets almost a mile, up and down badlands, including a very steep hill at the end. And all without one word of complaint. Way to go YCC!

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