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We recently finished up our excavations at Ghost Ranch. It was a very successful season; we collected over 1,000 specimens ranging from fragments to skulls and skeletons, and several hundred pounds of screenwash concentrate to be picked through at the lab. This year seemed to be the year of the phytosaur we found many more specimens of this group of animals compared to last year.
The last week of excavations we were joined by the Ghost Ranch paleontology field seminar. This group is a bunch of folks who are interested in paleontology and excited to have a chance to join excavations. They are also invaluable in the field we had a dozen people this year so it tripled our workforce. The seminar participants found many significant specimens and were a great help!
Making a plaster jacket
The key is to immobilize the rock and fossil so it comes back to the lab in one piece. The first step is to dig a trench around the entire bone, so that it is elevated on a pedestal, sort of like a mushroom. Later we will "pop" the "mushroom cap" away from the ground in one piece. The second step is to cover the pedestaled bone and rock with damp toilet paper. We apply the water with a brush so that the toilet paper conforms tightly to the surface. The reason for applying this layer is that it separates the next layer, plaster, from the bone, and prevents them from sticking to each other.
The next step is to make some kind of jacket to protect the fossil. The type of jacket depends on how large your pedestaled fossil is. If it is smaller than a foot across, you can cover it with plaster medical bandages, the exact same thing that a doctor will use to put a protective cast around a broken bone. Because our pedestal is much larger, we'll be using plaster and burlap strips. Both of these methods achieve the same result; they form a hard plaster shell that keeps the inside contents from moving about or breaking apart.
The method explained here is decidedly low-tech it hasn't changed in over 100 years! No one has found a better way to remove fossils, so we continue to follow the method of vertebrate paleontology pioneers.
All photos by Sarah Werning, UCMP.
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